(FES) Applied to the Gluteus Medius During Resistance Training

Home , Gait deviations

A Thesis

entitled

The Effect of Functional Electrical Stimulation (FES) Applied to the Gluteus Medius

During Resistance Training

Matthew M. Robinson, AT, ATC

Submitted to the Graduate Faculty as partial fulfillment of the requirements for the

Master of Science Degree in Exercise Science

______Neal Glaviano, PhD, AT, ATC, Committee Chair

______Matthew Robinson, AT, ATC, Committee Member

______Grant Norte, PhD, AT, ATC, CSCS, Committee Member

______Amanda Murray, PT, DPT, PhD, Committee Member

______Amanda Bryant-Friedrich, PhD, Dean College of Graduate Studies

The University of Toledo

May 2018

This document is copyrighted material. Under copyright law, no parts of this document may be reproduced without the expressed permission of the author.

An Abstract of

The Effects of Functional Electrical Stimulation (FES) Applied to the Gluteus Medius During Resistance Training

Matthew M. Robinson, AT, ATC

Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Exercise Science

The University of Toledo May 2018

Randomized Controlled Single-Blinded Controlled Laboratory Trial. Setting: Laboratory.

Patients or Other Participants: 22 healthy adult females (Age: 21.8±1.4yrs, Mass:

76.9±18.8kg, Height: 1.7±.1m). Intervention(s): Participants were randomized to 2 resistance training groups. FES which administered a visible comfortable contraction of the GMed during therapeutic exercise or sham treatment with no stimulation during exercise. Protocol was composed of 4 exercises (3x10), 3 times a week for 2-weeks. Main Outcome Measure(s): All variables tested pre/post 2-week intervention. GMed torque was assessed via HHD (Nm/kg), normalized GMed activity during SLS (percentage MVIC), and frontal plane projection angle

(FPPA) during a SLS. Cohens d effect sizes and 95% confidence intervals were calculated.

Results: Groups were similar at baseline. Both groups demonstrated FPPA improvements

(FES:Pre-16.13±8.63, Post-9.13±8.04,p=.006; Sham:Pre-16.28±5.97, Post-

11.31±5.11,p=.012). No differences in hip abduction torque (FES:Pre-0.750.18,Post-0.760.18

Nm/kg; Sham:Pre-0.680.17,Post-0.750.15 Nm/kg,p=.148). Large effect size found in FES group for FPPA (d=.84[-.03,1.71]). Sham group demonstrated a large effect size for SLS EMG post-intervention (FES:d=.55[-.3,1.4];Sham:d=.93[.05,1.81]). Conclusions: Our findings imply that resistance training of 2-weeks with/without FES both elicited improvements in FPPA that exceeded the standard error of measure (3.2). Additionally, those in FES group had higher expectation of treatment thus solidifying use of FES in clinical practice. Word Count: 294

Table of Contents

Abstract iii

Table of Contents v

List of Tables vii

List of Figures viii

List of Abbreviations ix

I. Manuscript 1

A. Introduction 1

B. Methods 3

a. Study Design 3

b. Participants 3

c. Instrumentation 4

d. Procedures 6

e. Resistance Training Program 8

f. Follow-Up Testing 9

g. Data Reduction 9

h. Statistical Analysis 10

C. Results 10

a. Dynamic Single Limb Control 10

b. Hip Abductor Isometric Muscle Torque 11

c. Hip Abductor Activity During MVIC and Squatting Task 11

d. Relationships Between Variables 11

f. Credibility and Expectancy 11

D. Discussion 12

E. Conclusion 16

References 24

Appendices

A. The Problem 33

B. Literature Review 39

C. Additional Methods 64

D. Additional Results 95

E. Back Matter 113

F. Bibliography 117

List of Tables

Table 1 Resistance Training Intervention ...... 17

Table 2 Pre and Post FPPA During the Single Leg Squat ...... 18

Table 3 Hip Torque Pre/Post-Intervention ...... 19

Table 4 Credibility and Expectancy Questionnaire Results ...... 20

Table 5 Electrical Stimulation Parameters & Results ...... 54

Table 6 Functional Electrical Stimulation Parameters & Results ...... 61

vii

List of Figures

Figure 1 Subject Set-Up for Single Leg Squat/FPPA ...... 21

Figure 2 Between Group Effect Sizes ...... 22

Figure 3 Gluteus Medius Activity during the MVIC and SLS ...... 23

viii

List of Abbreviations

ACL...... Anterior Cruciate Ligament ACL-R...... Anterior Cruciate Ligament Reconstruction

DKV ...... Dynamic Knee Valgus

EMG ...... Electromyography ES ...... Electrical Stimulation

FES ...... Functional Electrical Stimulation FPPA ...... Frontal Plane Projection Angle FST ...... Functional Stabilization Training

GMed ...... Gluteus Medius

HHD ...... Handheld Dynamometer

IMU ...... Inertial Measurement Unit

JRF ...... Joint Reaction Force

KAM ...... Knee Adduction Moment

LSI...... Limb Symmetry Index

MVIC ...... Maximum Voluntary Isometric Contraction %MVIC ...... Percent Maximum Voluntary Isometric Contraction

NEMG ...... Normalized Electromyography NMES ...... Neuromuscular Electrical Stimulation NWB ...... Non-Weight Bearing

OA ...... Osteoarthritis

PENS ...... Patterned Electrical Neuromuscular Stimulation PFP ...... Patellofemoral Pain

SLS ...... Single Leg Squat STSTS ...... Sit-To-Stand-To-Sit

TA ...... Tibialis Anterior

VAS...... Visual Analog Scale

WB ...... Weight Bearing

Chapter One

Manuscript

Introduction

Weakness of the gluteus medius (GMed) is often visible in activities of daily living for healthy and pathological patients alike, and has been studied during stair ambulation, walking, and stepping tasks in patients with osteoarthritis.1,2 Additionally,

GMed weakness is commonly seen by clinicians who treat a variety of lower extremity pathologies.3-7 Due to the role of the GMed in proper functioning of the lower limb, clinicians often utilize resistance training programs to target this muscle and focus on proper activation and movement patterns. Previous literature suggests GMed strengthening programs, utilizing a variety of non-weight bearing, weight bearing and functional exercises, are effective in managing pain and improving frontal plane kinematics in female patients with GMed weakness.8-10

The GMed’s key functions is to maintain pelvic stability and control frontal and transverse motion of the hip. This is commonly referred to as dynamic knee valgus

(DKV), and often presents as increased hip adduction, hip internal rotation, and knee abduction.11 This weakness is often clinically defined by maximal isometric output testing utilizing handheld dynamometry, which has been shown to be clinically reliable in the literature.12,13 Functional weakness of the GMed can be assessed in frontal plane movement during functional tasks like a single leg squat (SLS).14 This altered frontal plane motion is concerning, as it can shift the center of mass away from the stabilizing stance limb, predisposing the individual to additional comorbidities due to altered loading of the joint.15 Increased hip adduction and knee abduction may place an individual at

higher risk for sustaining an anterior cruciate ligament (ACL) injury or development of patellofemoral pain.16,17 Therefore, it is essential for clinicians to develop interventions in order to improve frontal plane motion and reduce potential injuries.

In clinical practice, electrical stimulation (ES) is often used during the initial stages of muscle injury or post-operative care.18 The goal of ES is to stimulate the inhibited muscle and improve function of the patient.19 Additionally, ES is utilized for strength improvements, decreasing pain, and reducing atrophy.19 ES is most prevalently used in a static fashion (i.e. during isometric tasks on a table) as there are limitations when using it during functional therapeutic exercises (i.e. wiring limits the capacity of functional tasks that can occur).18,20 In an active capacity, functional electrical stimulation

(FES) is the process of pairing an electrical stimulation simultaneously or intermittently with a functional task.21 FES has been shown to improve gait in post-stroke patients who experience a lack of abduction or foot drop due to inhibition of the GMed and tibialis anterior respectively.22-24 However, there is limited research examining the effects an

FES intervention during a resistance training program in individuals who present with altered frontal plane motion during a SLS.

As stated previously when determining the root cause of GMed weakness a proper differential diagnosis should be determined. However; with single limb tasks like the

SLS, the GMed should always be considered as it plays a role in DKV which results in pathologically concerning mechanics.14,25 On top of a focused resistance training program, FES may provide a unique approach to improving frontal plane kinematics during single leg squat, muscle activation, and torque through superimposing electrical stimulation to the GMed during therapeutic exercise. There have been similar studies to

which FES has been applied during resistance training and gait trials with notable success.19,22-24 The purpose of this study was to examine the effectiveness of a 2-week strengthening program with or without FES on GMed function, for frontal plane kinematics during single leg squat, increasing muscle torque, and muscle activation. We hypothesize that utilizing FES during strength training will improve dynamic single limb control and function in healthy patients demonstrating GMed weakness.

Methods

Study Design: This study was a randomized, single-blinded, controlled laboratory study comparing 2-weeks of traditional resistance training with and without the addition of FES to the GMed muscle. Our independent variables were group (2-week

GMed strengthening program with or without FES) and time (pre and post-intervention).

The primary dependent variable was frontal plane projection angle (FPPA) during a SLS task. Secondary dependent variables were hip abduction torque, muscle activity assessed by electromyography (EMG) during the squatting task and hip abduction task. The relationship for change scores between these dependent variables was also assessed.

Credibility/expectancy of treatments was assessed by the Credibility and Expectancy

Questionnaire (CEQ).

Participants: 22 recreationally active healthy females (Age: 21.8±1.4yrs, Mass:

76.9±18.8kg, Height: 1.7±.1m) with DKV were recruited from the University of Toledo and local community. Inclusion criterion consists of DKV; assessed by the relationship between the patella and big toe during a squat.26-28 Dominant limb was chosen based on which limb the subject would kick a ball with. All participants were physically active (at least 20 minutes of exercise at least 3 days a week) and had no history of lower extremity

or back injury within the last 6 months, history of rupture to any knee ligaments or meniscus. Participants were asked to maintain their normal daily activities and to not initiate any strength training programs. Exclusion criteria excludes participants with implanted biomedical devices, current pregnancy, cardiovascular disease, head injury

(TBI, Concussion, etc.) in the last year, BMI greater than 28kg/m2, neurological diseases, or medical contraindications for electrical stimulation.23,29-37 Sample size estimation was calculated from Dawson et al.27, which found a 6.2° improvement in FPPA in females during a SLS following a hip strengthening program, with a standard deviation of 4.5°.

With these values, alpha level at 0.05, and desired power of 0.80 we would need 9 subjects per group. With a 20% attrition rate, 11 subjects per group, for a total of 22 total subjects were enrolled.

Instrumentation: Pain during SLS was quantified both pre- and post-intervention using a 10cm Visual Analog Scale (VAS) that listed “No Pain” and “Worst Pain

Imaginable”. Use of the VAS has shown moderate validity and reliability.38 VAS was collected to control for any potential confounding influence of pain during the squatting task. Level of physical activity was assessed by the Godin-Leisure Time Activity and

Tegner Activity Scale at baseline. Credibility and expectancy for the interventions were evaluated via a therapy evaluation form completed after the final strength training session.

The FPPA was used to assess DKV and was calculated using ImageJ software.

Retroreflective markers were placed on the anterior superior iliac spine, midpoint between femoral condyles, and the midpoint of the ankle mortise of the test limb (Figure

1).39 High-speed cameras (Sony A7200 High Definition Mini-Camera, Tokyo, Japan)

were placed perpendicular to frontal plane at a mark 2m anterior to the subject and in line with the knee joint from a sagittal view.

Hip abduction strength was operationally defined as the maximal isometric hip abduction torque. Hip abduction isometric force was measured using the Microfet 2

MMT HHD (Hogan Scientific, Salt Lake City, UT). Testing of torque was completed in a side lying position with strapping, which has excellent reliability (ICC=0.97).40 The handheld dynamometer was calibrated prior to data collection. A double bar rectangular wireless electrode (Noraxon, Scottsdale, AZ) was placed halfway between the most superior portion of the posterior iliac crest and greater trochanter.41 The electrode was oriented in alignment with the GMed muscle fibers.42 EMG data was collected at a sampling rate of 2,000Hz. EMG was band-pass filtered at 35-500Hz with a notch filter of

60Hz. myoMotion wireless IMUs (Noraxon, Scottsdale, AZ) were placed on the pelvis, thigh and shank of the test limb. IMU data was used to identify initiation and completion of the squat to allow for increased accuracy of analyzing squatting EMG data.

The FES was applied with a Compex Wireless USA Muscle Stimulator (Compex

USA, Vista, CA). The stimulus is a biphasic waveform with a 50Hz frequency and a 200- microsecond phase duration. 2x2” self-adhesive electrodes were placed over the inferior and superior portions of the GMed muscle, identified by palpation of the greater trochanter and most superior aspect of the posterior iliac crest. Identical set-ups were conducted on both treatment groups. Individuals randomized to the FES group received electrical stimulation to the GMed during the resistance exercises. The amplitude was increased to elicit a strong but comfortable contraction. The stimulus is superimposed to when the patient initiates contraction of their GMed during the strengthening tasks. Speed

of the exercises are controlled to 2-second eccentric and 2-second concentric phases to help standardize the application of electrical stimulation. Participants in the sham group had an identical set; however, the electrical stimulation output is only set to 1mA to allow for the unit display to light up.

Procedures: Eligible participants were screened for DKV prior to enrolling in this study. Potential participants completed three SLS and the researcher (M.R.) assessed the position of their patella relative to their great toe. Participants were eligible if the patella was medial to the great toe for two out of the three squats. Participants provided informed consent, were screened for inclusion/exclusion criteria and completed the

Godin-Leisure and Tegner Activity Scales.

A wireless EMG electrode was placed over a cleaned, shaved, and debrided muscle belly of the GMed. The EMG signal was assessed by completing a hip abduction task. Once the EMG set-up was completed, participant’s GMed maximal voluntary isometric contraction (MVIC) was collected. Participants were placed in a side-lying position on a treatment table. A pillow was placed between the legs so the hip may be abducted approximately 10° which is measured in respect to a line connecting the anterior iliac spines. Strapping was used proximal to the iliac crest and secured underneath the table to stabilize the trunk. The center of the HHD was placed over a mark

5 cm proximal to the lateral knee joint line. This distance was measured to the hip axis of rotation. The dynamometer was placed between the leg and second strap that was wrapped around the leg and underside of table. The participant’s limb was placed in a slightly extended and externally rotated position.37 The “make” test was used for collection of both pre and post-intervention measurements. Participants underwent 1

practice trial and 3 experimental trials where maximal force was applied against the strap for 5 seconds. 15 seconds of rest were provided between each trial. The peak value in kilograms was collected.37

Following testing for torque, one inertial sensor was placed at the pelvis, and two inertial sensors were placed on the lateral aspect of the participant’s dominant thigh and shank. Dominant limb was defined as which lower limb the participant would use to kick a ball. Participants were introduced to SLS task, which required participants to complete a SLS that descend beyond 60° of knee flexion for a period of 5 seconds.28,43 During the practice period, participants were given audible feedback on their SLS depth to ensure the depth was below 60° of knee flexion. Following the practice trial, participants completed five separate squats at the selected speed. Trials were considered successful if the participant completed the squatting task without losing their balance, maintained the appropriate speed of the tasks, and squatted to the appropriate depth. Participants were provided a minute rest between trials. If the trial was unsuccessful, participants repeated the trial. Participants completed a VAS to assess pain level during the squat.

After completing baseline data collection, participants scheduled their training sessions with the researcher. Participants were instructed to not change their normal daily activities over the 2-weeks. Participants were also asked to record their physical activity for the duration of the study. Participants were randomly assigned to one of the two groups: 1) resistance training with FES, or 2) resistance training without FES.

Randomization was conducted prior to the first subject enrolled via sealed envelopes allocated by the principle investigator.

Resistance Training Program: The first day of the resistance-training program occurred a minimum of 48 hours after baseline session. Participants completed 3 supervised resistance-training sessions per week for 2-weeks. Each session was supervised by a single certified athletic trainer who provided the blinded FES or sham treatment, provided exercise instructions, and monitored compliance. Those allocated to the FES group were told they would experience a strong muscle contraction, while those in the sham group were told they would be receiving a sub-sensory stimulation. Identical resistance training programs were completed between groups and are outlined in Table 1.

The speed of each exercise was standardized with a metronome to a 4-second movement;

2-seconds of a concentric contraction and 2-seconds of an eccentric contraction. Those randomized to the FES group had a superimposed muscular contraction for the duration of the task and those in the sham group received the sham treatment through the duration.

For the side-lying hip abduction task, participants were positioned in a side-lying position with both limbs in full extension with a neutral position. A weight, standardized to 10% of the subject’s hip abduction MVIC was secured to the distal limb at the ankle mortise. Participant slowly raised their limb into 30 degrees of hip abduction and then slowly returned their limb to the starting position.44 Seated hip external rotation placed the participant in a short-seated position with a theraband secured around the distal limb at the ankle mortise. Participants externally rotated their hip against the resistance applied by the athletic trainer.45 Participants stood on their dominant limb on a step that was 10% of their height to complete the lateral step-down task. Participants kept their non- dominant limb in full extension and ankle dorsiflexion. Participants lowered themselves until their heel met the ground and then returned to the starting position.46 Pelvis drop

task required participant to stand on their non-dominant limb on a step that was 10% of their height. Participants lowered their hip to the ground and then raise their hip to the ceiling.47

Sets and repetitions were held constant throughout the 2-week training protocol with no progression. Participant training program compliance was recorded for the duration of the 2-weeks in a journal by the research team; which included each session date and time, exercises completed, and FES amplitude for the intervention group. Every training session was scheduled between the participants and the research team and contact information was exchanged between all involved members. This allowed for communication between involved parties to ensure compliance and allow for rescheduling any potential conflicts. Upon completing the final resistance training session, subjects were asked to fill out the CEQ.

Follow-Up Testing: Upon completion of the 2-week resistance training program participants completed follow-up testing identical to the baseline measurements. Post- intervention torque, FPPA with EMG and a VAS during the squatting task were collected. Participants also returned their self-reported physical activity over the last 2- weeks. These follow-up measures were taken approximately 24-48 hours after completion of the final resistance training session.

Data Reduction: Data from the two cameras were exported and single frames were identified; when the participant was in a single limb stance just prior to knee flexion and when the knee was in maximal flexion. These frames were recorded and the FPPA was calculated by measuring the angle of the bisected thigh segment to the bisected shank segment. The FPPA was calculated by taking the difference between the maximal knee

flexion position from the single limb stance position.26,43 The average of three trials were used for data analysis. Strength was assessed by calculating torque, normalized to the patient’s body mass (Nm/kg). Virtual event markers were inserted in the myoMotion software to process the EMG data, by using the IMU’s to identifying the initiation of knee flexion and terminal knee extension. Data was exported between these two-time points to calculate muscle activity for the task in its entirety. The mean amplitude EMG data during the task was normalized as a percentage of the MVIC EMG data (%MVIC).26

Statistical Analysis: A mixed measures ANOVA was conducted with between group factors being group (FES or sham) and within factor being time (pre, post- intervention). T-tests were used for post hoc testing to identify significant differences in the presence of significant interactions or main effect. Significance was set a priori p≤0.05. Cohen’s d effect sizes were calculated with 95% confidence intervals to determine magnitude of differences. Effect size interpretation was set at: <0.20 (trivial),

0.20-0.49 (small), 0.50-0.79 (moderate), and ≥0.80 (large).48 Pearson r correlation coefficients were utilized to calculate the relationship between changes in torque, muscle activity, and FPPA. Correlation coefficient interpretation was set at: 0-0.4 (weak), 0.4-0.7

(moderate), and 0.7-1.0 (strong).49 Data was analyzed using Statistical Package for Social

Sciences (SPSS) V23.0 (SPSS, Inc., Chicago, IL).

Results

Dynamic Single Limb Control: FPPA for both groups was similar at baseline

(Table 2). There was an improvement for FPPA in both groups over the 2-week intervention regardless of treatment allocation (Table 2). Large effects that did not cross

zero were identified between groups (Figure 2). There was no difference in VAS scores between either group when performing SLS pre/post intervention (p>.05).

Hip Abductor Isometric Muscle Torque: No differences between groups for hip abduction torque at baseline (Table 3). No differences in hip abduction torque (FES: Pre:

0.750.18, Post: 0.760.18 Nm/kg; Sham: Pre: 0.680.17, Post: 0.750.15 Nm/kg, p=.148). Small effect sizes were identified pre/post intervention for both groups (Figure

2).

Hip Abductor Activity During MVIC and Squatting Task: There were no differences in GMed activity during hip abduction MVIC trials at baseline and between groups pre/post intervention. However, an increase was identified in the sham group for

GMed activation during SLS (Figure 3). Effect sizes for GMed EMG was identified pre/post intervention and is outlined in Figure 2.

Relationships Between Variables: Correlations were run examining relationships between pre/post intervention for all variables. There were no correlations identified independent of treatment allocation. Correlations for all participants were therefore reported together. No correlations were found between changes in hip abduction and FPPA (r=.119, p=.599) or between muscle activity during SLS and FPPA (r=-.205, p=.36).

Credibility and Expectancy: Values for CEQ between groups are reported in

Table 4. When dividing the questionnaire into its subcomponents we found no difference between groups for credibility (FES: 23.72.28, Sham: 21.723.37, p=.12), however the

FES group was found to have a higher expectancy score (FES: 19.993.8, Sham:

15.865.12, p=.045).

Discussion

The purpose of this study was to examine the effectiveness of a 2-week resistance training program with or without FES on FPPA, muscle torque, and muscle activation.

The main finding of this study was that a 2-week resistance training program with or without FES led to improvements in FPPA for both groups. The 2-week intervention with

FES did not result in a difference between groups for hip abduction torque. As well, no differences were observed between baseline and post testing for GMed activity during

MVIC. However, a significant difference was found in that GMed activity during SLS was higher in the sham group. We did see a significant difference in the expectancy subgroup of the CEQ, with those allocated to the FES group expecting a greater improvement in their squatting mechanics.

The change in FPPA upon completion of resistance training in the FES group reflects the findings of previous studies which examined FPPA before and after a longer course of training.27,50 Our study resulted in a 7-degree improvement in the SLS FPPA, which is like other training programs that have improved FPPA by 8 degrees and 6.9 degrees by Herrington et al.50 and Dawson et al.27 respectively. However, it should be noted that our improvements occurred following a 2-week strength intervention with

FES, while the previous authors completed a longer intervention. While no changes in torque were identified, improvements in the FPPA could be due to neuromuscular adaptations following a 2-week resistance training program with high activation exercises targeting the GMed.28 While it is not known the optimal duration of training to influence frontal plane motion during FPPA assessment, we did see that a 2-week training program was found to be beneficial for improving FPPA above the standard error of measurement

threshold of 3.22 degrees. However, it should be noted that while we had a large effect size for both FES and sham group, we did not reach the smallest detectable difference threshold of 8.93 for the SLS.28 This may suggest that a longer training intervention is required, as Herrington et al.50 did cross this threshold with their 6-week intervention.

There were no differences in the hip abduction torque for either group throughout the intervention. While hypertrophy gains require 6-weeks of training, previous studies have found improvements in strength following interventions with ES below this 6-week window.51,52 There is also some evidence of improved torque output during the electrical stimulation treatment.53 We also found no difference in GMed activity during the MVIC assessment. However, we did see a significant increase in GMed activity during the SLS for the sham group. While it is difficult to speculate why this difference was identified, the squatting mechanics may play a role in this outcome. Additionally, it is possible that assessing GMed weakness by poor SLS mechanics as utilized in our inclusion criteria may incorrectly classify participants. While altered frontal plane motion has an association with GMed weakness, there is a possibility that some of these individuals had altered motor coordination without deficits in GMed activity.14 It may be important for clinicians to identify differences between strength and altered motor control to be able to develop appropriate interventions, facilitated by feedback, movement training, or strength training when treating these patients.

While we did assess frontal plane motion with the FPAA, this 2-dimensional assessment does not measure in the transverse plane. This can be limiting when it comes to evaluating a dynamic task like that of the SLS, we were unable to establish any differences in hip rotation or other transverse movements. Additionally, the variable of

trunk lean could be assessed by adding more markers to the subject’s torso. This would allow clinicians a better insight as to whether the DKV is being inhibited by alterations in trunk lean to compensate for lack of GMed control in frontal plane kinematics. Having a full biomechanical assessment would provide insight if the two groups altered their transverse motion, which may contribute to the demands of the GMed to control motion in that plane.

We attempted to minimize any variables that could have influenced the squatting task, which was used to assess frontal plane motion. Pain has been identified to limit muscle activation and squatting mechanics.54-56 Whereas, Callaghan et al. identified higher levels of self-reported pain correlated to higher levels of arthrogenic muscle inhibition of the quadriceps.57 Additionally, Bazett-Jones et al. induced pain in patients with PFP via a SLS protocol, which in turn led to both pain elevation and decreased hip- extensor strength.54 However, in our study both groups presented with no difference in pain during squatting across the time points. We did assess activity level for both groups over the 2-week intervention. All subjects remained active throughout the study and did not change their daily habits. Subjects were instructed not to change their daily activity to prevent any unwarranted effects on the training intervention they were enduring.

Therefore, changes that occurred between baseline and follow-up testing can be attributed to the strengthening intervention and not that of pain during the task or changes in physical activity.

Subjects allocated to the FES group were found to have higher expectancy scores compared to those in the sham group. Values for credibility between FES and sham interventions were similar. Previous studies have exhibited similar changes when

assessing credibility (is the intervention credible) (25.02.2) and expectancy (the extent to which they thought the treatment would have them improve) (21.93.9).58 Those in the

FES group were found to have a higher value for expectancy, which is likely due to

“feeling” a difference throughout their course of treatment. Those allocated to the FES experienced a superimposed contraction of the GMed which likely influenced the higher expectancy. Thus, a feeling of the GMed contraction prior to their own. Due to the novel nature of FES, this intervention can be re-applied to several other pathologically weak muscles that are commonly targeted in rehabilitation. Patient expectation has been found to have a significant influence on patient outcomes, suggesting the need for clinicians to focus on patient centered care.59 Additionally, clinicians should view FES to improve outcomes in rehabilitation through the psychological effect that FES adds.

There are some potential limitations with the current study. First, we indirectly assessed GMed weakness by visually inspecting DKV during a SLS. While this is one method to assess GMed function, it may not be specific to identify true muscle weakness of the GMed. Secondly, the current length of the study was only 2-weeks long, which may not be long enough to elicit changes in muscle function or neuromuscular control.

Often, hypertrophy is not seen in such a short intervention; therefore, much of the changes reflected in the data can be attributed to neuromuscular adaptations. Previous studies indicate changes in muscle thickness and cross sectional area does not occur until greater than four weeks have been completed in a resistance training program.60 Future research is needed to examine the effects of a longer training program with superimposed electrical stimulation on GMed functional capacity. Additionally, we only used EMG to measure GMed activity during two tasks. Due to the multiple GMed fiber orientation and

their differences in function, that may have minimized to assess a more complete assessment of gluteal function following the intervention. Focus on the posterior fibers of the GMed and superior fibers of the gluteus maximus should also be examined, due to their roles in controlling frontal plane and transverse motion. Lastly, it is currently unknown the optimal number of exercises required to improve muscle function. The study selected the four exercises included since previous literature has identified them to target the GMed muscle. It is unclear if more exercises would have resulted in differences within the study.

Conclusion

Our findings imply that a resistance training intervention of 2-weeks with or without FES elicited improvements in FPPA above the standard error of measure. In addition to improved FPPA, the FES group had a higher expectation of success, as reported on their CEQ. Superimposing electrical stimulation during therapeutic exercise may improve patient outcomes and further research should be conducted incorporating

FES into a longer strength training intervention. Based on these findings, FES presents as a potential tool for clinicians to utilize to improve patient expectations during therapeutic exercise.

Tables

Table 1. Resistance Training Intervention Exercise Sets Reps Side-Lying Abduction (w/ ankle weight; 10% of GMed MVIC) 3 10 Seated Hip External Rotation (w/TheraBand) 3 10 Lateral Step Down (Standardized to 10% of subject’s height) 3 10 Pelvic Drop Task 3 10 GMed: gluteus medius, MVIC: maximal voluntary isometric contraction

Table 2. Pre and Post FPPA During the Single Leg Squat

FPPA

Pre Post p-value

FES 16.13±8.63 9.13±8.04 .006

Sham 16.28±5.97 11.31±5.11 .012

FPPA: frontal plane projection angle, FES: functional electrical stimulation

Table 4. Credibility and Expectancy Questionnaire Results

Group Credibility Expectancy

FES 23.7±2.28 19.99±3.8

p=.120 p=.045 Sham 21.72±3.37 15.86±5.12

FES: functional electrical stimulation

Figures

Figure 1. Subject Set-Up

Figure 2. Between Group Effect Sizes

Figure 3. Gluteus Medius Activity during the MVIC and SLS

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Appendix A

The Problem

Problem Statement

The gluteus medius plays a vital role in the function of humans, whether it is walking, running, lifting, or even standing. Weakness of the gluteus medius can lead to pathologies at the ankle, knee, hip, and low back. Therefore, its consideration in rehabilitation and resistance training is vital. Increased “hip drop”, especially in the female population is a moment of increased hip adduction, internal rotation, and knee valgus.1 This movement leads to a predisposition of ACL rupture, medial joint line compression, osteoarthritis, patellofemoral pain, low back pain, and foot/ankle pathologies.2 Traditionally electrical stimulation has been used to facilitate muscle activation and function, it has been found that these improvements may aid in injury prevention. Functional electrical stimulation (FES) is an emerging wearable therapeutic modality that has been shown to improve activation of impaired muscles in multiple pathological groups to improve altered movement patterns.3 However, FES has not yet been applied during resistance training with the focus of improving gluteus medius activity during functional tasks. The purpose of this study will be to examine the effectiveness of FES applied to the gluteus medius as an intervention to improve the dynamic control of females with hip drop in the frontal plane of movement.

Research Question

1. Following a strength training protocol, do patients with gluteus medius weakness

exhibit improved strength and function with the addition of functional electrical

stimulation?

Experimental Hypothesis

1. Utilizing electrical stimulation as an intervention for use during strength training

will improve strength and function in patients with gluteus medius weakness.

Assumptions

• Subject will provide maximal effort during isometric contractions

• Subjects will provide accurate data on their physical activity during the duration

of the study

• Subjects will perform their squat in the laboratory as they would at any other time

• Subjects will perform their squat to their maximal capability

• Subjects will be vetted for dynamic knee valgus via single leg squat and FPPA

measurement

• Subjects will undergo measurement of possible additional outcomes (i.e. strength

assessment, EMG activity, and/or visual analog scale for pain assessment)

Delimitations

• Number of trials

• Procedures for EMG normalization

• Procedures for isometric strength testing

• Procedures for FPPA/SLS

• Use of Tegner and Godin activity scale

• Inclusion

o Patient Population – females w/ dynamic knee valgus

o Ability to self-ambulate

• Exclusion

o ACL-R exclusion due to altered movement patterns

o LE injury in last 6mo-1yr (ankle, knee, hip)

o Cardiovascular disease

o Pregnancy

o Previous injury to the back

o Leg length discrepancy >2cm

o Previous head injury in lifetime (TBI, Concussion, etc.)

o Musculoskeletal disease

o BMI greater than 28kg/m2

o Neurological or cognitive diseases that may impair motor function

o Medical and psychological contraindications for electrical stimulation

Limitations

• Length of study

• Amount of exercises

• Middle fibers for EMG of GMed

Operational Definitions

• ACL – Anterior Cruciate Ligament

• ACL-R – Anterior Cruciate Ligament Reconstruction

• Dynamic Knee Valgus – due to weakness of the hip musculature, the concept of

dynamic knee valgus may occur. This abnormality is best described as the knee

“collapsing” during functional movement. Visually, this can be noted as the most

medial portion of the knee crossing over the great toe.

• EMG – Electromyography

• ES – Electrical Stimulation

• FES – Functional Electrical Stimulation

• FPPA – Frontal Plane Projection Angle is a 2-D measurement of dynamic knee

valgus. The patient performs a single leg squat and a photo is taken at the lowest

point of the squat. By using anatomical markers, clinicians can record an

objective measurement of dynamic knee valgus in patients.

• GMed – Gluteus Medius

• JRF – Joint Reaction Force increased levels of force distribution that may be

localized to the medial and/or lateral portion of a joint. In patients where this is

increased, they may have an increased likelihood of osteoarthritis formation.

• KAM – Knee Adduction Moment is a surrogate term used to describe the amount

of compartmental loading in the knee joint. Lack of hip musculature control leads

to this instance of pelvic drop.

• LSI – Limb Symmetry Index is a way to normalize extremity function. Takes

strength measures of the “worse” limb and is divided over the strength of the

“better” limb, described as a function.

• MVIC – Maximum Voluntary Isometric Contraction is the maximum isometric

contraction of a muscle a patient can produce in one instance.

• %MVIC – Percent Maximum Voluntary Isometric Contraction

• NEMG – Normalized Electromyography

• NMES – Neuromuscular Electrical Stimulation

• NWB – Non-Weight bearing

• OA – Osteoarthritis

• PENS – Patterned Electrical Neuromuscular Stimulation

• PFP – Patellofemoral Pain

• SLS – Single Leg Squat

• TA – Tibialis Anterior

• WB – Weight bearing

Significance of Study

The use of functional electrical stimulation (FES) has been detailed in the literature for treatment of “drop foot” in post-stroke patients. It has also been used to stimulate the GMed to improve ambulation in patient’s post-stroke. However, it has not yet been established as to whether FES can improve function and efficiency of muscle groups during resistance training. Previous literature regarding FES mainly focuses on facilitation of proper ambulation in post-stroke patients; however, the application of FES is beginning to become recognized as a tool to improve muscular function during functional tasks in post ACL-R patients. New studies examining the application of FES during resistance training solidifies the significance and innovation of our study.

Adding FES to traditional resistance training prospectively allows the clinician to function in a more efficient fashion by adding a superimposed stimulus to the patient’s own contraction. Athletic trainers are constantly looking for better tactics to combat muscle weakness, and FES may be of emerging use to gain quicker and longer lasting results.

By stimulating the muscle directly during resistance training we may find more beneficial and longer lasting outcomes. Due to the GMed’s overall function, it is of importance when it comes to day-to-day life activities. By increasing its activation and overall function, we may see an increase in lower extremity function, osteoarthritis development, low back pain, and patellofemoral pain to name a few.

Appendix B

Literature Review

Introduction

The hip is an integral part in the day-to-day function of humans. In the simplest of tasks, such as walking, running, lifting or even standing, the musculature surrounding the hips is active during these tasks. The main muscle, which stabilizes the contralateral hip during gait, is the gluteus medius (GMed). The GMed is made up of multiple portions

(anterior, middle, posterior), this muscle runs from the anterior iliac crest to the greater trochanter of the femur in a vertical direction.4 The GMed is seen to envelop the greater trochanter of the femur, which solidifies is role as an abductor and stabilizer of the hip.5

To gain a better understanding of the three different fiber arrangements of the GMed, they will be looked at individually. The anterior fibers act to not only abduct the hip but also internally rotate the hip. The middle fibers of the GMed run in a line parallel to the femur, this enables the middle GMed to aid in stabilization of the femoral head in the acetabulum of the innominate bone.4 As well, the posterior fibers will provide external rotation of the hip when contracted.5 The multiple fibers of the GMed create for a challenging understanding of its overall function. There has been a great deal of research pertaining to the best clinical implications for GMed strengthening, which will be touched on later in this review.

The utilization of modalities in functional training is of common application for athletic trainers, physical therapists, and occupational therapists alike. It is often difficult to isolate the contraction of certain muscles in a clinical rehabilitation setting. There are

numerous studies that have examined the maximal voluntary isometric contraction

(MVIC) of the gluteal muscles; however, there is limited evidence that have examined targeting the gluteals with electrical stimulation (ES).

The GMed functions to maintain hip abduction; however, it also plays a large role in injury prevention studies pertaining to tears of the anterior cruciate ligament (ACL).

Numerous studies have been performed looking at the function of the proximal muscles of the kinetic chain at the hip. The gluteal muscles are often targeted for their role in stabilization of the proximal portion of the kinetic chain. The hip muscles may also aid in prevention of lower kinetic chain injury.2 The following injuries may be due to weakness at the hip: tibial stress fracture, low back pain, iliotibial band friction syndrome, ACL injury, and patellofemoral pathology.2

In the clinical setting, there is always a need to get patients back to competition, daily life, leisure sports, etc. Utilization of FES may allow this to occur. Traditionally

FES is applied to stroke patients to activate muscles that may have been damaged during the ischemic period. Most commonly, the tibialis anterior is targeted due to the “foot drop” that occurs post-stroke. There are variations of FES used in these patients, which can be described as internal and external FES. Internal FES is implanted and stimulates the nerve directly, while external is applied via surface electrodes.6

1. Muscle Weakness

Decreased proximal hip strength and neuromuscular control may predispose individuals to dynamic lower extremity valgus and further pathological injury,

specifically patellofemoral pain and ACL injury.7 The term dynamic lower extremity valgus can be described as not just one movement pattern, but a combination of hip adduction and internal rotation, knee abduction, tibial external rotation and anterior translation, and ankle eversion.8 Additional concern may be brought on by patients exhibiting contralateral pelvic drop and/or hip abductor weakness (i.e. GMed) that can cause a shift in the center of mass away from the stabilizing stance limb.9 Impaired hip control exhibit possible risk factors for predisposition to lower extremity injury, therefore calling for additional intervention to aid in the reduction of these risk factors.

Identification of muscle weakness in the hip is not always easily determined, however in patients with GMed weakness pelvic drop and dynamic knee valgus is often exhibited. Weakness of the GMed is often visible in activities of daily living, and has been studied using electromyography during stair ambulation, walking, and stepping tasks in patients with osteoarthritis.10 Even basic testing of the GMed via a handheld dynamometer can provide clinicians with a specific idea of the isometric output of this muscle. A more advanced way to screen for hip weakness during a functional task is using a single leg squat (SLS). A positive SLS test insinuates not only poor lower extremity mechanics but also inhibited levels of lower extremity control. Patients that exhibit a positive SLS test will also demonstrate increased levels of dynamic valgus in additional tasks like the drop jump test.11

The SLS is performed by standing on one leg and descending as far as possible to at least 30-45 degrees of knee flexion and then returning to a fully extended position.11-13

Abnormal responses during this test can be described as flailing of the arms,

Trendelenburg sign, or collapse of the support knee.11 Flailing of the arms can be attributed to lack of balance and core control by the patient during the task.11 The

Trendelenburg sign occurs when the patient lacks GMed control and subsequently

“drops” their hip during the SLS movement.11 Collapse of the knee is a term that correlates to the knee moving into an adducted or valgus position.11 These three abnormalities constitute great concern in that they have been shown to lead to elevated risk of ACL injury.14

To quantify the concept of dynamic lower extremity valgus, frontal plane projection angle (FPPA) may provide an objective insight into this pathological concern and aid in identification of patients with GMed weakness. The FPPA is a two- dimensional calculation representing the amount of dynamic lower extremity valgus taking place during a functional task. Markers are placed on the lower extremity at the midpoint of the femoral condyles, midpoint of the ankle malleoli, and on the proximal thigh along a line from the anterior superior iliac spine to the knee marker. During the task, digital photographs are taken and the FPPA is calculated utilizing the markers. The

FPPA is found to be negative if the knee marker is medial to a line from the ankle to the thigh marker. On the other hand, the FPPA is positive if the knee marker is lateral to a line from the ankle to the thigh marker.15 Willson et al.15 found that FPPA was of viable use for objective measurement of lower extremity alignment. As well, they established that the FPPA measurement might be a good option for screening individuals for dynamic lower extremity valgus during functional weight-bearing activity.16

The use of FPPA has been limited in the literature, however some researches have begun to investigate is as a probable tool for diagnosis of dynamic lower extremity valgus.12 It has been noted that an increased FPPA is associated with an increase in stress on the ACL and patellofemoral joint, which are two very common locations of pathological concern.17 Paz et al.18 examined the use of FPPA in youth basketball players during drop vertical jump and forward step-up functional tasks. Results of this study indicated that there was little difference in FPPA between non-dominant (20°) and dominant (20.2°) extremities. However, there was a noted difference between FPPA in the forward step-up task, non-dominant (18.7°) and dominant (21.7°).18 This finding correlates to the lack of non-dominant limb control often seen in the youth athlete population.19-21

1.1 Pathological Muscle Weakness

Muscles surrounding the hip play an important role in the controlled movement of the femur in the frontal and sagittal planes of movement. Weakness to the GMed often has a clinical presentation of increased adduction at the hip and greater valgus stress at the knee.22-25 Increase knee valgus and hip internal rotation may also be due to weakness of the “deep six” external rotators of the hip (piriformis, obturator internus and externus, gemellus superior and inferior, and quadratus femoris).22,23,26 In terms of overall function of the GMed, it can be noted that the GMed concentrically abducts the hip, isometrically contracts to stabilize the pelvis, and fires eccentrically to control internal rotation and adduction of the hip.27 If a muscle is experiencing weakness it will not produce adequate torque compared to a normal contraction, thus producing less torque and affecting the

ability of said muscle to accelerate or decelerate the limb.28 Concurrent research has found that the gluteus maximus functions to control frontal plane movement, rather than sagittal, during activities like walking and stair ambulation.28,29 The above muscles play a vital role in the global movement and control of the hip.

A link has been established between patients with patellofemoral pain (PFP) and weakness of the hips.1 The pathology of PFP is often of insidious onset and lacks a true mechanism or presence of damage to the intra-articular portion of the knee.30 Patients that exhibit symptoms of PFP will often have an incidence of internal rotation and hip adduction during function tasks of the lower extremity, this “collapse” is directly associated with eccentric GMed weakness.28 Weakness of the GMed will result in an increase in hip adduction and internal rotation, which will increase the dynamic quadriceps angle during functional tasks like walking, jogging, lifting, and stair ambulation.22 Previous researchers23,31-33 have identified that patients with PFP will exhibit decreased isometric strength of the hip extensors, external rotators, and abductors.28 Patients with PFP have been reported to have 26-27% decreased hip abduction strength23,28,31,33, 24-30% less hip external rotation strength23,28,31,33, and 52% less hip extension strength compared to healthy controls.28,33 These findings establish a further connection that weakness of the hip musculature can in fact lead to increased probability of PFP.

Weakness of the hip musculature in the active population may lead to compensation by surrounding musculature.34 This compensation will occur via associated muscles at the low back, hip and knee; thus altering the function of those muscles as

well.35 Powers et al.36 revealed that female PFP patients exhibited 4.3° greater knee external rotation, 3.5° greater hip abduction, and 3.9° less internal rotation of the hip during running, single leg jumping and single leg squatting. This increased hip internal rotation may be a compensation strategy for PFP patients to reduce their quadriceps angle during weight bearing tasks.36-38 A concomitant compensation found in patients with hip abductor weakness is an increased ipsilateral trunk lean. Due to this compensation, the resultant ground reaction force vector will reposition closer to the center of the hip joint, this lessening the demand placed on the abductors of the hip.39,40 When ipsilateral trunk lean is increased, another sequela may be a more lateral ground reaction vector, thus creating an increased valgus force at the knee joint.41 The valgus force created by the compensation may also increase the dynamic quadriceps angle and change the lateral force vector acting on the patella.9,22

Additional pathological concerns relating to GMed weakness have to do with increased medial joint reaction force (JRF).42 This force placed on the medial aspect of the knee may lead to the early onset of osteoarthritis (OA), an inflammation of the bone on the femur or tibia.42 Increased hip adduction and internal rotation, due to GMed weakness, may increase contact pressure to the lateral patella during functional tasks.37

The knee adduction moment (KAM) is a term used to describe the compartmental loading of the knee.43 Higher incidence of KAM may lead to increased pain, narrowing of joint space, and increased cartilage deterioration.44-46 Additional researchers have noted that patients with higher peak KAM at initial measurement and KAM impulse had an increased incidence of OA progression.47,48 Since there is presently no cure for OA,

clinicians are searching for ways to delay the progression of this disease. Improved

GMed strength may lead to decreased KAM, which in turn may improve kinematics of the joint and reduce OA symptoms.49

Due to the importance of the hip abductors influence on stability of the hip, isolation of these muscles in rehabilitation is imperative. To achieve a better understanding of the muscles used in therapeutic exercise, electromyography (EMG) is often utilized to objectively measure the electrical activity of a muscle of interest.34 Force output of these muscles has been interpreted as a percentage of MVIC (%MVIC), this value can be interpreted to reflect that a higher percentage will yield an increase in strength gains.50 When a muscle produces a higher %MVIC, an increased level of motor control will occur and therefore improved joint stabilization. This solidifies the fact that, to successfully train the GMed, a good understanding of muscle function is imperative to positive outcomes.50

To combat GMed weakness, therapeutic exercise has often been used to increase eccentric and concentric strength in this muscle. Strengthening of the hip musculature is an important tool for any clinician, however differences in activation have not yet been established for non-weight-bearing (NWB) and weight-bearing (WB) exercise.35

Numerous studies have compiled data on the effectiveness of gluteal strengthening, the main way to establish which ones are effective is by using the %MVIC as stated previously. When a higher %MVIC is elicited, the exercise will yield an increase in hypertrophy of the muscle being targeted (GMed).2

When creating a viable strengthening program for the GMed, it is important to consider exercises that obtain greater than 40%MVIC in order to elicit strength gains.51

Researchers, have established a list of exercises that produce increased %MVIC of the

GMed the following produced higher than 70%MVIC: side plank abduction with dominant leg on bottom (103%MVIC), side plank with dominant leg on top (89%MVIC), single limb squat (82%MVIC), clamshell progression four (77%MVIC), and front plank with hip extension (75%MVIC).2

Ayotte et al.51 compiled data regarding the EMG function of the gluteus maximus, gluteus medius, vastus medialis oblique, and biceps femoris whilst performing five WB tasks in a unilateral stance. Normalized EMG (NEMG) was utilized as a measure of activation, and the interaction of thigh and hip muscles during unilateral WB tasks and the muscular activation achieved.51 The following was found upon completion: wall squat

(52%MVIC), mini squat (36%MVIC), forward step-up (44%MVIC), lateral step-up

(38%MVIC), and retro step-up (37%MVIC).51 Exercises with lower NEMG values

(lateral step-up, retro step-up, and mini-squat) should be utilized earlier on in rehabilitation and prevention protocols to allow the patient to initiate GMed strength gains and control.51

Additional research has been compiled to establish GMed activation levels for exercises utilized by clinicians. In a study conducted by Distefano et al.52 a total of twelve exercises were organized into a “top tier” and “lower tier”. It was concluded that five exercises would be in the top tier and seven would be in the lower tier. The top tier exercises are as follows: hip abduction in side lying (81%MVIC), single-limb squat

(64%MVIC), lateral band walk (61%MVIC), single-limb deadlift (58%MVIC), and sideways hop (57%MVIC).52 All five of these exercises involve the main actions of the

GMed, therefore should be of primary use when considering the GMed in prevention or rehabilitation exercise prescription. On the other hand, Distefano et al.52 noted seven exercises that have lower activation of the GMed, but can be used early on to initiate

GMed activity. The lower tier exercises are as follows: transverse hop (48%MVIC), transverse lunge (48%MVIC), forward hop (45%MVIC), forward lunge (42%MVIC), clam with 30° hip flexion (40%MVIC), sideways lunge (39%MVIC), and clam with 60° hip flexion (38%MVIC).52 However, as stated previously, it is important to take note of

%MVIC when choosing exercises considering Ayotte et al’s51 finding that in order to elicit strength gains MVIC of 40%MVIC and greater should be elicited.

In a systematic review, Reiman et al.53 found nine exercises that elicited high- level activation (41-60% MVIC) of the GMed: lateral step-up (41%MVIC), quadruped stance with contralateral arm and leg lifting (42%MVIC), forward step-up (44%MVIC), unilateral bridge (47%MVIC), transverse lunge (48%MVIC), wall squat (52%MVIC), side-lying hip abduction (56%MVIC), pelvic drop (57%MVIC), and single-limb deadlift

(58%MVIC). As well, Reiman et al.53 found two exercises that elicited very high-level activation (>60% MVIC). The single-limb squat (64%MVIC) and side-bridge to neutral spine position (74%MVIC) was found to meet said criteria for this activation level.53

Strengthening programs have been proposed for use in patients with PFP to combat weakness at the knee and/or hip. Researchers54, found improved pain relief scores in PFP patients who underwent a hip and knee resistance training program versus a

traditional knee-only program. Patients performed a 5-min warm-up, then a 20-min stretching and strengthening program, followed by a 5-min cool down. The knee-only group completed the following with a resistance band: isometric quadriceps sets, straight leg raise, mini squat, and knee extension. While the knee and hip group completed standing hip abduction and seated hip external rotation in addition to the knee exercises.

Overall, it was established that both programs reduced pain scores, however the hip and knee group demonstrated far more improved pain, functional tests, self-reported function, and isokinetic torque of hip abductors and external rotators over the traditional knee-only protocol.54

Additionally, Dolak et al.55 established that hip abductor and external rotator strengthening is more beneficial for patients with PFP rather than quadriceps strengthening programs. Not only is training the hip abductors and external rotators important, but training of the core-stabilizers has been found to reduce patellofemoral joint loading through improved stability of the lumbopelvic region.56

The utilization of a multi-faceted GMed functional stabilization training (FST) program to combat PFP in females was utilized by Baldon et al.57 revealed decreased pain upon three month follow up versus a standard training program. The FST program consisted of exercises previously utilized by the author with the main goal of enhancing motor control of the trunk and hip musculature during the first two weeks. In the subsequent three weeks, the main goal of the program was improved strength gains.

Upon the final three weeks, patients were challenged with more difficult tasks and improved education regarding frontal plane alignment of the hips and decreasing

quadriceps dominance through decreased trunk lean. At conclusion of the training protocol, patients in the FST group were found to have less pain upon a three month follow up. Additionally, they were found to have greater global improvements and physical function when compared to the standard training group. The following were only observed in those completing the FST program: lesser ipsilateral trunk inclination, contralateral pelvis depression, hip adduction, and knee abduction, along with greater pelvic anteversion and hip flexion movement during single leg squatting tasks. Therefore, when compiling a program to combat PFP, it is important to consider the addition of motor training programs and control exercises involving the trunk and lower-limb considering the beneficial outcomes related to decreased pain and improved global function of the lower extremities.57

1.2 Post-Surgical Muscle Weakness

In patients that have undergone anterior cruciate ligament reconstruction (ACL-

R), quadriceps weakness is said to continue long after the rehabilitation process is completed. Patients with said deficits are found to redistribute torque from the quadriceps to the hips while performing functional tasks.58 Bell et al.58 examined these proposed deficits and compensations in 62 patients that had undergone unilateral ACL-R with a time from surgery equal to 30.9 ±17.6 months. Patients were divided into low (<85% limb symmetry index (LSI) and high quadriceps groups (≥90% LSI). Reconstructed limbs in the low quadriceps group were found to be overall weaker than all other limbs in the study (P < 0.001). The low quadriceps group was also shown to have greater hip extension strength bilaterally (P = 0.007), while the high quadriceps group was shown to

have decreased knee flexion strength in the ACL-R limb (P = 0.047).58 The increased gluteus maximus (hip extensor) and soleus activity in ACL-R patients is said to help overcome quadriceps weakness and compensate to slow the body during the landing phase of gait.59

A variety of studies have observed ACL-R patients using both proximal and distal compensation strategies during multiple movements like squatting60, hopping61,62, and gait.63,64 Noehren et al.65 found that ACL-R patients exhibited decreased hip flexion angles and compensated with increased hip extensor activity. These compensations often occur bilaterally in ACL-R patients, therefore resulting in increased utilization of the hip musculature. Focus on hip strengthening during rehabilitation is often used, however it can lead to a long term dependence on this strategy in this population.58

2. Electrical Stimulation

ES relates to the activation of a muscle by artificial means, and acts directly on pain receptors.66 The main function of ES is to apply stimulus to the joint or area in order to elicit a muscular contraction with goals of improving strength, edema reduction, decreasing atrophy, and alleviation of pain.67

Application of ES on muscles acts directly on the nerve rather than the muscle fibers itself. When a muscle is innervated in a normal fashion, ES will elicit a contraction through excitation of the nerve rather than the muscle fiber. The reasoning for this is due to the threshold of the nerve being lower than that of the muscle fiber; therefore, nerves are poised to stimulate in a quicker fashion than muscles. When electrical stimulation is

applied, areas of large fiber diameter will stimulate with lower amplitude compared to fibers with smaller diameters.68

An additional form of ES is neuromuscular electrical stimulation (NMES), this is a common treatment for bypass of the reflexive inhibitory loop.69 This technique often requires a stimulus current that is equal to or greater than that of 60% of the MVIC.70

Electrical stimulation may be applied in various ways; however, when applied to weakened muscles, the electrical current will cause a contraction via the neuromuscular junction and surrounding muscle fibers, this type of stimulation is termed NMES.71

NMES is utilized via the application of intermittent stimuli to skeletal muscle groups, the main objective of this form of ES is to trigger observable muscle contractions due to intramuscular nerve branch activation.72 The stimulus is delivered using one or multiple electrodes placed near the muscle motor points, as well as a programmable stimulation unit. It is imperative to have an intact motor nerve in order to achieve muscular contractions with NMES.73 NMES has been largely used in the research community, as well as the clinical setting in order to rehabilitate and even train individuals.73 Objectively speaking, the main goals of NMES are as follows: improvement of maximal force output and force endurance.71 These variables are achieved through repetitive muscular contractions.71

Glaviano et al.74 examined the effectiveness of a novel form of ES, patterned electrical neuromuscular stimulation (PENS). This form of ES is used on the basis of improving neuromuscular re-education, and recreating firing patterns of normally functioning muscle groups.74 This research aids our current study in that it is also

recreating firing patterns of a normally functioning muscle to improve the targeting and efficiency of GMed training.

2.1 Parameters

Parameters of ES often differ based on desired outcome measures. The following parameters and results (Table 5), outline treatments that are considered viable in comparison to this study. Many of the below studies had differing treatment parameters based on their study goals; however, all resulted in positive and beneficial outcomes for the functional capacity of the patients in terms of muscle function, activation, strength, torque, and presence of pain.75-78

Table 5. Electrical Stimulation Parameters & Results

Study Subjects, n Results Labanca et al.75 63 35 and 50 Hz NMES frequencies were applied, max intensity of 120 mA was allotted. NMES+STSTS showed improved knee extensor strength, lower pain perception, and higher symmetry in lower extremity loading. Taradaj et al.76 80 NMES group received biphasic symmetrical rectangular pulses with a frequency of 2500 Hz and a frequency of train pulse at 50 Hz applied three times daily, three days a week for one month. Shown to be useful for strengthening quadriceps. Pantovic et al.77 15 Intervention of NMES with a 110 Hz current for 13’. Warm-up (10 mA, 5 Hz, 5’), and workout plyometry (13’). Steady tetanic stimulations were administered for 6 sec. at a time (110 Hz) during exercise then 18 sec of rest. NMES resulted in improved torque, indicating addition of NMES is better than traditional resistance training.

Glaviano et al.78 22 Intervention of 15’ PENS (biphasic square-wave pattern 50 Hz, 70 sec phase duration, 200 sec stimulus train) treatment or sham group. Improvement in GMed activation (PENS group) during lateral step down. Improvements in VAS for lateral step down and SLS in treatment group. NMES: neuromuscular electrical stimulation, STSTS: sit to stand to sit, PENS: patterned electrical neuromuscular stimulation, GMed: gluteus medius, VAS: visual analog scale, SLS: single leg squat

The parameters detailed in the above studies will be elaborated on in the following paragraphs. There are numerous forms of electrical stimulation; for example,

low voltage, direct current, transcutaneous electrical neuromuscular, neuromuscular, interferential, Russian, and high voltage to name a few.68 The main parameters of concern regarding electrical stimulation are phase duration, pulse duration, frequency, and duty cycle.

In muscles, electrical stimulation will elicit a contraction by stimulation of the nerve rather than the muscle fiber.68 This occurs because the nerve fibers will react to the electrical stimulus far quicker than the muscle fiber due to the decreased stimulus threshold of the nerve.68

Most electrical stimulation waveforms are made up of periodic sinusoids of different amplitude, phase, and frequency.68 The term frequency equates to the stimulation occurrences per second.68 On the other hand, phase is the difference between the start (zero point) of the fundamental cycle and the end of the fundamental frequency.68 Phase may also be described as current flow in one direction for a definite period of time.68 The parameter of phase can also be expressed as phase/pulse duration, which is the change in time from beginning to end of a single phase of a pulse or a period of alternating current.68 These are typically short in order to prevent temperature elevations in the muscles that are stimulated.68 With that being said, phase duration is expressed in microseconds or milliseconds.68 The concept of pulse duration can also be described as having an influence on torque production without implications like muscular fatigue. When pulse durations are longer, they may have more of an effect on motor fibers versus sensory fibers.79-81

When applying electrical stimulation practically there are often periods of active stimulus and periods of rest, this is expressed as a ratio.68 Therefore, another parameter of

importance is the duty cycle; this can be defined as the ratio of time on (active stimulus) to the total time of the electrical stimulation.68

2.2 Use of Electrical Stimulation

Electrical stimulation programs for strength improvement are commonly used by clinicians and have been validated by numerous researchers.69,76-78,82 Taradaj et al.76 evaluated a neuromuscular electrical stimulation (NMES) program on quadriceps strength in post-operative ACL patients. They identified that use of NMES improved quadriceps strength from 645.9 to 893.4 N (28.7%, P = 0.001), compared to the control group’s quadriceps strength improvement of 648.6 to 669.8 N (4.6%, P = 0.04). Overall, the study promoted use of NMES on post-operative ACL patients due to their large increase in power and mass of the quadriceps muscle group.76

In terms of muscular performance after NMES treatment, it has been concluded that average isokinetic torque and peak torque of the quadriceps femoris at 90 and 210 degrees per second is significantly greater (p < 0.05) than volitional exercise.69

Additionally it was determined that NMES has the ability to increase quadriceps performance (increased from 40% in the first six months to 80% twenty-four months post-op) in patients who have undergone ACL-R, and the torque produced by this group was nearly 70% of the contralateral limb.69

Like the work of Taradaj et al.76, a study observing the outcomes of various

NMES groups on vertical jump execution was performed by Paillard et al.82 Patients underwent one of three conditions: the control group or C group (no NMES), and two sub groups that underwent 3 training sessions per week over a 5-week period focusing on the quadriceps femoris—the F group was subjected to an 80Hz current for 15min (goal of

improving strength), and E group underwent 25Hz for 60min (goal of improving endurance). Paillard et al.82 recorded vertical jump data prior to treatment, after one week, and five weeks after the program. Their findings revealed increased vertical jump in the two NMES groups after one week (5cm) and five weeks (3cm) thus solidifying

NMES as a viable intervention to increase vertical jump performance.82

Neuromuscular electrical stimulation is also viable for increasing MVIC through neural adaptions. Pantovic et al.77 completed a study looking at the use of NMES superimposed over voluntary contraction versus traditional resistance training programs.

Upon data collection, Pantovic et al.77 found that NMES was a viable option for increasing peak torque compared to traditional resistance training.

Patients with PFP often state pain is their primary ailment; however, on a physiological level it is often found that their muscles have an altered activity level. In a study looking at the effects of patterned electrical neuromuscular electrical stimulation

(PENS) on pain and muscle activation, it was found that after a single treatment muscle activation at the GMed increased during a lateral step down.78 The form of electrical stimulation known as PENS creates a pattern of muscle contractions that mimic that of healthy subject’s EMG activity.78,83

2.3 Limitations of Electrical Stimulation

Although the main limitation of electrical stimulation is its functional application, one primary negative component is muscle fatigue that may occur during treatment.

Fatigue may be due to the recruitment of alpha motor neurons during repetitive contractions while using electrical stimulation.66 Traditional applications of NMES have

been found to result in a decrease in torque output84,85, however modifying the stimulus pattern may overcome this limitation.74

Additionally, NMES has been associated with decreased functional application and differences between electrically and physically induced muscle contraction.73,86

Maffiuletti et al.87 suggests that NMES target fast motor units, which is ideal for post- operative and post-injury treatment; however, greater discomfort, muscle damage, and earlier incidence of fatigue have been noted.

In terms of being applied during functional movement, ES has not typically been used beyond the initial rehabilitative stage.73 It has been noted that ES is very beneficial for use during open kinetic chain therapeutic exercise (i.e. isometric quadriceps sets and knee extension exercises), but these exercises do not transfer over to later functional therapeutic exercise during the return to sport phase.88,89

3. Functional Electrical Stimulation

Just like any aspect of medicine, the use of electrical stimulation is ever expanding. The utilization of FES has come into light for its effect on improved function in stroke patients. FES applies a direct stimulus to the muscle via external surface electrodes or implantation of a FES stimulation device within the patient.6 The use of

FES has become a viable and cost effective option for stroke patients to improvement strength, performance, range of motion, pain reduction, and lessened spasticity.3

Traditionally, the application of FES is primarily on the tibialis anterior (TA).

Stimulation of this muscle aids in the action of foot dorsiflexion, which is imperative in the swing phase of gait where the foot needs to clear the ground.3 Typically, stroke

patients are unable to generate enough force of the TA due to dysfunction of the common peroneal nerve.6

Although the use of FES has been primarily applied to the TA to correct the lack of plantar flexion or “foot drop” in the swing phase, this does not correct abnormal weight bearing dysfunction during the stance phase of gait in post-stroke patients. Lack of function in this phase of gait may attribute to altered weight bearing and weight shifting in patients that have suffered from a stroke.3 Therefore, application of FES to the

GMed has been studied to see if stance phase dysfunction can be improved. When applied to the GMed, FES can facilitate improved activation during double stance phase and the initial half of single limb support. Overall, application of FES to both the TA and

GMed can allow stroke patients to perform a more normalized gait pattern.3 This modality has yet to be applied to other tasks like resistance training, and has not been applied to additional pathological populations. FES applied in addition to resistance training is unfound in the literature, therefore showing gaps that need to be filled.

The concept of FES has not only been applied to the lower extremity of stroke patients, but also in the upper extremity of hemiparetic stroke patients. Makowski et al.90 looked at the application of FES combined with a neuroprosthesis in effort to combine FES and voluntary contraction. The application of FES in these patients would better allow them to complete functional movements as simple as reaching and opening of the hand. FES was deemed capable of increased force production while voluntary effort was produced simultaneously. However, this increase in force is dependent on the patient’s level of voluntary force production. Makowski et al.90 did note that even though this is the case,

FES can still be used as a viable option to augment the movements in patients with post- stroke pathological dysfunction.

3.1 Parameters

The parameters detailed in Table 6 show both similarities and differences in the literature when it comes to how researchers have utilized FES. One commonality between studies is a pulse width of at least 200 sec. Additionally, each study uses a frequency around 40 Hz with the only difference coming from Makowski et al.90 who used a 33 Hz frequency. The only other major difference between studies was Makowski et al.’s90 use of an amplitude of 40-60 mA. Although Labanca et al.75 did not classify their intervention as FES, the NMES treatment during sit to stand to sit training in ACL-

R patients, it still may be considered an FES intervention. This study correlated improvements in all categories and is of viable use for clinicians working with ACL-R patients. Overall, all studies saw improvement in function of patients who were involved in FES treatment groups.

Table 6. Functional Electrical Stimulation Parameters & Results Study Subjects, n Results Makowski et al.90 6 FES applied to augment force of patient. Surface electrodes delivered a pulse frequency of 33 Hz, amplitude of 40-60 mA, and a pulse width of 0 sec-255 sec. Superimposed stimulus can improve force in presence of voluntary effort. However, is dependent on level of voluntary effort. Kim et al.91 36 Surface FES electrodes delivered asymmetric biphasic wave with a frequency of 40 Hz and a pulse of 250 sec. Use of FES on GMed (during stance phase) and TA (during swing phase) improved spatiotemporal parameters of gait in individuals with hemiparetic stroke. Chung et al.3 18 FES used a symmetric biphasic wave pattern with a frequency of 40 Hz and a pulse of 200 sec on the GMed and TA. Improvements found in gait velocity, cadence, stride length, and dynamic balance. Cho et al.92 36 FES was characterized by a symmetric biphasic wave with a frequency of 40 Hz and a pulse width of 200 sec on the GMed and/or TA. Treadmill training with FES increased lower limb muscle strength, balance, and gait capacities. This treatment can be a beneficial intervention in clinical setting for patients with chronic hemiparetic stroke. Labanca et al.75 63 35 and 50 Hz NMES frequencies were applied, max intensity of 120 mA was allotted. NMES+STSTS showed improved knee extensor strength, lower pain perception, and higher symmetry in lower extremity loading. FES: functional electrical stimulation, GMed: gluteus medius, TA: tibialis anterior, NMES: neuromuscular electrical stimulation, STSTS: sit to stand to sit

3.2 Use of Functional Electrical Stimulation

Use of FES on the GMed has been found to decrease medial JRF of the knee.42

An increase in JRF at the knee has been associated with an increased precedence of OA formation in patients with this dynamic condition. In simulations of increased GMed activity during walking, researchers found a medial JRF reduction of 4.2% compared to the control trials.42 When FES was applied to the GMed during walking a medial JRF reduction of 12.5% was found.42 The results of this study concluded that the GMed has an important role in reduction of medial JRF and therefore increased protection of the knee in patients with OA.42 These findings support the need and importance of proper

GMed function; as well FES has been established as a viable intervention for increased

GMed activation during level walking.42 This increased GMed activation can attribute to changes in kinematics and alterations of ground reaction force parameters.42 Although not stated to be an FES intervention, researchers75 have found functional improvements in patients rehabilitating from ACL-R when NMES is applied during sit to stand to sit exercises.

3.3 Limitations of Functional Electrical Stimulation

Functional electrical stimulation has been previously used in post-stroke populations and has had a limited application in terms of application during functional resistance training tasks in a healthy population. There are many different types of electrical stimulators on the market currently and can vary from wired to wireless, therefore allowing countless options for functional training. The following may be potential limitations of FES: placement of pads, variability among stimulation units

(wired vs wireless), size of pads, and feasibility of ES during functional exercises. Pad placements may vary and can affect the accuracy of stimulation for the specific muscle of interest. Stimulation units are also variable in their functions and capabilities whether they be wired or wireless or even powered by a smart phone application. Additionally, adhesive pads utilized for training may vary in size and may have an impact on quality of stimulation depending on what muscle is of interest. In closing, FES may also be limited due to how much the patient truly believes in the intervention.

4. Conclusions

In terms of finding new ways to combat pathological weakness, clinicians are always striving to utilize the most advanced and clinically relevant therapeutic interventions. Modalities like ES, have been a long-time staple in the toolbox of athletic trainers and physical therapists for improving the activation of specific muscles. With some recent literature regarding application of NMES during functional tasks (sit to stand to sit) there is some promise that such functional ES interventions are gaining more prevalent use in the clinical setting.75 The GMed is unique in that it is a muscle which functions in multiple planes of movement and when weak, has been attributed to a multitude of pathological conditions.1,2 FES has been proven as an applicable modality to improve gait through improved GMed and TA activation in post-stroke populations.3,42

However, there is limited research examining the effects an FES intervention in a healthy population exhibiting GMed weakness during functional tasks. This literature review provides much of the background information behind ES, FES, GMed weakness, and

GMed pathological concerns and shall provide guidance for further research regarding the effects of FES on GMed control and activation during functional tasks.

Appendix C

Additional Methods

Executive Summary

Title: The Effect of Functional Electrical Stimulation (FES) Applied to the Gluteus

Medius During Resistance Training

Principal Investigator: Neal Glaviano, PhD, AT, ATC (Assistant Professor)

Research Team: Matthew Robinson, AT, ATC (Co-Investigator)

Grant Norte, PhD, AT, ATC, CSCS (Assistant Professor)

Amanda Murray, DPT, PhD (Assistant Professor)

Purpose: To determine if functional electrical stimulation applied to the GMed over a 2-week resistance-training program in females with dynamic knee valgus will improve frontal plane projection angle, strength, efficiency and pain level.

Participants: 22 Adult Females with Dynamic Knee Valgus

Inclusion Criteria: No history of lower extremity/back injury within last 6 months

No history of rupture to any knee ligaments or meniscus

Exclusion Criteria: Implanted biomedical devices

Current pregnancy

Cardiovascular disease

Head injury (TBI, concussion, etc.)

BMI greater than 28kg/m2

Neurological diseases

Contraindications for electrical stimulation

Study Design: Randomized Controlled Single-Blinded Clinical Trial

Independent Variable:

1. Group (2-week GMed strengthening program with or without functional

electrical stimulation)

2. Time (pre and post-intervention)

Dependent Variables:

1. Frontal Plane Projection Angle (during single leg squat)

2. Gluteus Medius Strength

3. Gluteus Medius Electromyography (during single leg squat)

Procedures:

1. Recruit physically active females with dynamic knee valgus

2. Vetting of subjects utilizing single leg squat task

3. Complete informed consent form

4. Provide Tegner Activity Level Scale and Godin Leisure-Time questionnaire’s

5. Wireless EMG placed over GMed, handheld dynamometer will establish

strength measurement

6. Inertial measurement sensors applied for single leg squat task

7. Cameras will be placed anterior and sagittal to subject for frontal plane

projection angle measurement during squatting task

8. Visual analog pain scale administered after task

9. Post-baseline collection, training sessions will be scheduled

10. Participants will be randomly assigned to intervention or sham group

11. Subject returns three times a week for 2-week program

12. Upon training program completion, steps #5-7 will be repeated

13. Subject will be formally dismissed from program

IRB Protocol: No. 201990

Statistical Analysis: A 2x2 mixed model ANOVA will be conducted. Between group factor will be group (FES or sham) and within factor with repeated measures will be time

(pre, post). Tukey’s post hoc tests will be used to identify significant differences in the presence of significant interactions or main effect. Significance will be set a priori p≤0.05. Cohen’s d effect sizes will be calculated with 95% confidence intervals to determine magnitude of differences. Effect size interpretation will be set at: <0.20

(trivial), 0.20-0.49 (small), 0.50-0.79 (moderate), and ≥0.80 (large). Pearson r correlation coefficients will be utilized to calculate the relationship between changes in strength, muscle activity, and FPPA. Correlation coefficient interpretation will be set at: 0-0.4

(weak), 0.4-0.7 (moderate), and 0.7-1.0 (strong).

Research Hypothesis:

1. Functional electrical stimulation will have a statistically and clinically

significant improvement in subject FPPA compared to baseline values.

2. The sham group will not have statistically and clinically significant

improvement in subject FPPA compared to baseline values.

3. The intervention group will see a significant improvement in GMed strength

and muscle activation during single leg squatting between pre and post-

intervention testing.

4. The sham group will not see significant improvements in GMed strength and

muscle activation during single leg squatting between pre and post-

intervention testing.

Consent Form

UT IRB #: 201990 ICF Version Date: 9/05/2017

School of Exercise and Rehabilitation Sciences 2801 W. Bancroft, MS 119 Toledo, OH 43606 Phone: (419) 530-5305 Fax: (419) 530-2477

ADULT RESEARCH SUBJECT INFORMATION AND CONSENT FORM and AUTHORIZATION FOR USE AND DISCLOSURE OF PROTECTED HEALTH INFORMATION

The Effect of Functional Electrical Stimulation (FES) Applied to the Gluteus Medius During Resistance Training

Principal Investigator: Neal Glaviano, PhD, ATC

Other Staff (identified by role): Matt Robinson, AT, ATC (Co-Investigator) Grant Norte, PhD, ATC, CSCS (Co-Investigator) Amanda Murray, PhD, PT (Co-Investigator)

Contact Phone number(s): Neal Glaviano (419) 530-4501 Matt Robinson (716) 245-8772

What You Should Know About This Research Study:

• We give you this consent/authorization form so that you may read about the purpose, risks, and benefits of this research study. All information in this form will be communicated to you verbally by the research staff as well. • Routine clinical care is based upon the best-known treatment and is provided with the main goal of helping the individual patient. The main goal of research studies is to gain knowledge that may help future patients. • We cannot promise that this research will benefit you. Just like routine care, this research can have side effects that can be serious or minor. • You have the right to refuse to take part in this research, or agree to take part now and change your mind later. • If you decide to take part in this research or not, or if you decide to take part now but change your mind later, your decision will not affect your routine care. • Please review this form carefully. Ask any questions before you decide about whether or not you want to take part in this research. If you decide to take part in this research, you may ask any additional questions at any time. • Your participation in this research is voluntary.

UNIVERSITY OF TOLEDO IRB APPROVAL DATE: 09/05/2017 EXPIRATION DATE: 09/04/2018

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UT IRB #: 201990 ICF Version Date: 9/05/2017

PURPOSE (WHY THIS RESEARCH IS BEING DONE)

The purpose of this study is to evaluate the effectiveness of resistance training and functional electrical stimulation (FES) in regard to knee position during a single leg squat. The goal of this study is to determine if the addition of FES will improve single limb control during a single leg squat. Our second goal is to evaluate the effectiveness of the 2-week resistance program on neuromuscular function of the gluteus medius(hip muscle). Overall, we hope to get information that may improve how clinicians and researchers treat gluteus medius weakness in a more effective manner.

You are being asked to be in this study because you are a female between the ages of 18 and 40, are physically active (exercise 3 times a week for 30 minutes), and when you squat your knee goes past your big toe (called dynamic knee valgus) AND (1) Have no previous injury to your back, hip, knee or ankle in the last 6 months, (2) have no prior history of surgery to your hip, knee, or ankle AND (3) contraindications to electrical stimulation (biomedical devices, pregnancy, cardiovascular disease and head injury).

Up to 50 people will be enrolled in this study at the University of Toledo.

DESCRIPTION OF THE RESEARCH PROCEDURES AND DURATION OF YOUR INVOLVEMENT

If you decide to take part in this study, you will be asked to report to the Musculoskeletal Health and Movement Sciences (MHMS) Laboratory at the University of Toledo for all testing.

Baseline Testing Session:

Eligibility Screening (about 5 minutes) You will be asked a series of questions via a questionnaire to establish your level of activity. You will then be taken through a series of three single leg squats to establish whether you may be eligible. We will be looking to see if your knee goes past your toes when you squat down.

Baseline Measurements (about 30 minutes) • Measurement 1 – Electromyography & Strength: o A wireless EMG electrode (small device that will measure how much your muscle turns on) will be placed over your gluteus medius muscle (the muscle on the outside of your hip). We may need to shave that area, clean it with rubbing alchol and use some gauze to rub away any dead skin cells. o You will be asked to laying on your side on a table with a pillow placed between both legs. o Straps will be placed around you at the hip and lower leg to prevent them from moving during the task. o A handheld dynamometer (small device that will measure how strong you are) will be placed above your knee. o Before testing your leg will be placed in a slightly extended and externally rotated position. o You will then have 1 practice trial and 3 experimental trials. o During these trials, you will kick up to the sky as hard as possible for 5-seconds. o You will be given 15 seconds of rest between each trial.

UNIVERSITY OF TOLEDO IRB APPROVAL DATE: 09/05/2017 EXPIRATION DATE: 09/04/2018

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UT IRB #: 201990 ICF Version Date: 9/05/2017

• Measurement 2 – Squatting Task: o Three sensors will be strapped around your waist, thigh, and lower leg. o You will then be given directions on how to do the single leg squat. o You will complete a single leg squat with your arms placed across your shoulders. o A squat will count when your knee bends past 60 degrees of knee flexion-the research team will help you know if you squat low enough. o You will do this squat at a rate of 15 squats per minute. We will use a metronome that will make a noise to let you know when to start and stop the squat o After your practice trial, you will complete five squats with a minute rest between each. o During your trials, both the computer system and two high-speed cameras will be used to record data. o After completion, you will be asked to complete a survey regarding any knee pain you may have had during the task.

You will have all markers and sensors removed. You will then schedule two-weeks of resistance training (approximately three times a week). You will be randomly assigned to one of the two groups (like flipping a coin): 1) resistance training with FES, or 2) resistance training without FES. Randomization will be conducted prior to the first person enrolled via sealed envelopes allocated by the principle investigator.

Resistance Training Sessions (about 30 minutes each) • The first day of the resistance-training program will occur a minimum of 48 hours after baseline session. You will complete 3 supervised resistance-training sessions per week for two weeks. • Each session will be supervised by a single certified athletic trainer who will provide the blinded FES or sham treatment, provide exercise instructions and monitor compliance. • FES is a electrical stimulus applied to a muscle during functional activity that helps stimulate the contraction of a weak muscle. • Those put into the FES group will have a superimposed muscular contraction to your gluteal muscles for the duration of the task. A superimposed muscular contraction means that when the stimulus is turned on, the muscle will contract. This is a common application seen in athletic training, physical therapy, and doctor’s offices. The superimposed contration should not result in any pain and will be monitored by a certified athletic trainer. • Those allocated to the sham group will have identical set up, however no electrical stimulus will be administered. These individuals will be instructed that they are receiving a “subsensory” stimulus, which is common in research when conducting a blinded study with electrical stimulation. • Identical resistance training programs will be completed by all individuals regardless of groups they are put into. Four exercises will be used in the resistance-training program; side-lying hip abduction, seated hip external rotation, lateral step-down and pelvic drop task (as described in detail below). Each task will be completed for 3 sets of 10 repetitions. The speed of each exercise will be standardized with a metronome to a 4-second movement; 2-seconds of a concentric contraction and 2-seconds of an eccentric contraction. Approximately 2 minutes of rest will be provided between exercises.

UNIVERSITY OF TOLEDO IRB APPROVAL DATE: 09/05/2017 EXPIRATION DATE: 09/04/2018

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UT IRB #: 201990 ICF Version Date: 9/05/2017

Side-Lying Hip Abduction (5 minutes) • You will be lying on your side position with both limbs in full extension(fully straightened out) with a neutral position. • A weight will be strapped to the end of your leg. • You will slowly raise your leg until it is about 12” higher than your other ankle, then slowly return your leg to the starting position.

Seated Hip External Rotation (5 minutes) • You will be seated on a stool with a theraband resistance band placed around the end of your leg.This band is like an elastic band and is used in exercise programs. • You will externally rotate your hip (Keep your thigh still, but turn your ankle across your body) against the resistance of the theraband.

Lateral Step-Down (5 minutes) • You will stand on your dominant leg on a step that is 10% of your height. • You will keep your non-dominant leg in full extension on the step. • You will lower yourself until your heel meets the ground and then return to starting position.

Pelvic Drop Task (5 minutes) • You will stand on your non-dominant leg on a step that is 10% of your height. • You will lower your hip to the ground and then raise your hip to the ceiling.

Session 2 (Approximately 40 minutes) • You will return to the laboratory. • You will complete an identical data collection to the Baseline Measurement session (outlined above). • Following this second testing session, you will be completed with the current study.

RISKS AND DISCOMFORTS YOU MAY EXPERIENCE IF YOU TAKE PART IN THIS RESEARCH

Likely Risks • Mild temporary muscle and/or hip/knee/ankle joint soreness after the movement exercises. If soreness occurs, it will very likely resolve on its own with no further problems. • Mild skin irritation from electrode pads for the muscle stimulation unit.

Unlikely Risks • There is a small risk of injury to your hip, knee, or ankle. This risk is unlikely if you have been cleared for full activity. • There is a small risk for falling during the step-down tasks. • There is a small risk of a breach in confidentiality. This risk is unlikely as the following safeguards have been put in place. All study-related forms will be kept in a locked filing cabinet in the Musculoskeletal Health and Movement Sciences laboratory. Only members of the investigative staff will have access to the filing cabinet. Within the data files, there will be nothing to identify the subject to the information. All forms will be coded by assigning each subject an ID number.

UNIVERSITY OF TOLEDO IRB APPROVAL DATE: 09/05/2017 EXPIRATION DATE: 09/04/2018

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UT IRB #: 201990 ICF Version Date: 9/05/2017

There are no known risks to unborn children at this point. There may be risks that the researchers are unaware of at this time.

POSSIBLE BENEFIT TO YOU IF YOU DECIDE TO TAKE PART IN THIS RESEARCH

We cannot and do not guarantee or promise that you will receive any benefits from this research. The information gained from this study aims to provide clinicains a more efficient and functional way to strengthen the gluteus medius muscle in a shorter period. The information from this study may also provide a reliable tool for interpreting dynamic control of the knee via frontal plane projection angle, as well as help improve patient care in regard to the rehabilitative process.

COST TO YOU FOR TAKING PART IN THIS STUDY

All procedures in this study will be provided at no cost to you or your health insurance. You will be responsible for the cost of travel to come to any study visit and for any parking costs.

PAYMENT OR OTHER COMPENSATION TO YOU FOR TAKING PART IN THIS RESEARCH

If you decide to take part in this research you will not receive any financial compensation for participating.

ALTERNATIVE(S) TO TAKING PART IN THIS RESEARCH

The only alternative to taking part in this research is not to participate. Your care through the University of Toledo Medical Center will not be affected should you decline participation.

CONFIDENTIALITY (USE AND DISCLOSURE OF YOUR PROTECTED HEALTH INFORMATION)

Participation in research involves using and sharing your health information to conduct the research. We will do our best to make sure that information about you is kept confidential, but we cannot guarantee total privacy. By agreeing to take part in this research study, you give to The University of Toledo (UT), the Principal Investigator and all personnel associated with this research study your permission to use or disclose health information that can be identified with you that we obtain in connection with this study.

We will use this information for the purpose of conducting the research study as described in the research consent/authorization form.

The information that we will use or disclose includes a description of your injury or surgery you’re your medical records. We may use this information ourselves, or we may disclose or provide access to the information to a statistician (for analysis of data) as part of the research study.

We may also use your information to contact you after this study is closed to update your contact information should we decide it is important to continue following your progress, or to open a new study to follow-up on people who take part in this study. To authorize research staff from The University of Toledo to contact you to update your information or invite you to participate in a new follow-up study, place your initials here: (opt-in).

UNIVERSITY OF TOLEDO IRB APPROVAL DATE: 09/05/2017 EXPIRATION DATE: 09/04/2018

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Under some circumstances, the Institutional Review Board, or the Research and Sponsored Programs of the University of Toledo or their designees may review your information for compliance audits. If you receive any payments for taking part in this study, your personal information and limited information about this study will be given to The University of Toledo’s accounts payable department as necessary to process payment to you. We may also disclose your protected health information when required by law, such as in response to judicial orders.

The University of Toledo is required by law to protect the privacy of your health information, and to use or disclose the information we obtain about you in connection with this research study only as authorized by you in this form. However, the information we disclose with your permission may no longer be protected by privacy laws. This means your information could be used and re-disclosed by the persons we give it to without your permission.

Your permission for us to use or disclose your protected health information as described in this section is voluntary. However, you will not be allowed to participate in the research study unless you give us your permission to use or disclose your protected health information by signing this document.

You have the right to revoke (cancel) the permission you have given to us to use or disclose your protected health information at any time by giving written notice to: Neal Glaviano, PhD, ATC at 2801 W. Bancroft St, HHS 2505K, Mail Stop 119, Toledo, OH 43606, 419-530-4501, [email protected]. However, a cancellation will not apply if we have acted with your permission, for example, information that already has been used or disclosed prior to the cancellation. Also, a cancellation will not prevent us from continuing to use and disclose information that was obtained prior to the cancellation as necessary to maintain the integrity of the research study.

Except as noted in the above paragraph, “your permission for us to use and disclose your protected health information has no expiration date.”

A more complete statement of University of Toledo’s Privacy Practices is set forth in its Joint Notice of Privacy Practices. If you have not already received this Notice, a member of the research team will provide this to you. f you have any further questions concerning privacy, you may contact the University of Toledo’s Privacy Officer at 419-383-6933.

IN THE EVENT OF A RESEARCH-RELATED INJURY

In the event of injury resulting from your taking part in this study, treatment can be obtained at a health care facility of your choice. You should understand that the costs of such treatment will be your responsibility. Financial compensation is not available through The University of Toledo or The University of Toledo Medical Center.

By signing this form you are not giving up any of your legal rights as a research subject. In the event of an injury, contact: Neal Glaviano, PhD, ATC at 419-530-4501 [email protected]

UNIVERSITY OF TOLEDO IRB APPROVAL DATE: 09/05/2017 EXPIRATION DATE: 09/04/2018

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UT IRB #: 201990 ICF Version Date: 9/05/2017

VOLUNTARY PARTICIPATION Taking part in this study is voluntary. You may refuse to participate or discontinue participation at any time without penalty or a loss of benefits to which you are otherwise entitled. If you decide not to participate or to discontinue participation, your decision will not affect your future relations with the University of Toledo or The University of Toledo Medical Center.

NEW FINDINGS You will be notified of new information that might change your decision to be in this study if any becomes available.

TEXT CONTINUED NEXT PAGE

UNIVERSITY OF TOLEDO IRB APPROVAL DATE: 09/05/2017 EXPIRATION DATE: 09/04/2018

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UT IRB #: 201990 ICF Version Date: 9/05/2017

OFFER TO ANSWER QUESTIONS Before you sign this form, please ask any questions on any aspect of this study that is unclear to you. You may take as much time as necessary to think it over. If you have questions regarding the research at any time before, during or after the study, you may contact:

Neal Glaviano, PhD, ATC at 419-530-4501 [email protected]

If you have questions beyond those answered by the research team or your rights as a research subject or research-related injuries, please feel free to contact the Chairperson of the University of Toledo Biomedical Institutional Review Board at 419-383-6796.

SIGNATURE SECTION (Please read carefully) YOU ARE MAKING A DECISION WHETHER OR NOT TO PARTICIPATE IN THIS RESEARCH STUDY. YOUR SIGNATURE INDICATES THAT YOU HAVE READ THE INFORMATION PROVIDED ABOVE, YOU HAVE HAD ALL YOUR QUESTIONS ANSWERED, AND YOU HAVE DECIDED TO TAKE PART IN THIS RESEARCH.

BY SIGNING THIS DOCUMENT YOU AUTHORIZE US TO USE OR DISCLOSE YOUR PROTECTED HEALTH INFORMATION AS DESCRIBED IN THIS FORM.

The date you sign this document to enroll in this study, that is, today’s date, MUST fall between the dates indicated on the approval stamp affixed to the bottom of each page. These dates indicate that this form is valid when you enroll in the study but do not reflect how long you may participate in the study. Each page of this Consent/Authorization Form is stamped to indicate the form’s validity as approved by the UT Biomedical Institutional Review Board (IRB).

Name of Subject (please print) Signature of Subject or Date Person Authorized to Consent

a.m. Relationship to the Subject (Healthcare Power of Attorney authority or Legal Guardian) Time p.m.

Name of Person Obtaining Consent Signature of Person Obtaining Consent Date (please print)

Name of Witness to Consent Process Signature of Witness to Consent Process Date (when required by ICH Guidelines) (when required by ICH Guidelines) (please print)

YOU WILL BE GIVEN A SIGNED COPY OF THIS FORM TO KEEP.

UNIVERSITY OF TOLEDO IRB APPROVAL DATE: 09/05/2017 EXPIRATION DATE: 09/04/2018

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Questionnaire’s

UT IRB# 201990 TEGNER ACTIVITY LEVEL SCALE

Please indicate in the spaces below the HIGHEST level of activity that you are able to participate in:

CURRENT: Level

Level 10 Competitive sports- soccer, football, rugby (national elite) Level 9 Competitive sports- soccer, football, rugby (lower divisions), ice hockey, wrestling, gymnastics, basketball Level 8 Competitive sports- racquetball or bandy, squash or badminton, track and field athletics (jumping, etc.), down-hill skiing Level 7 Competitive sports- tennis, running, motorcars speedway, handball

Recreational sports- soccer, football, rugby, bandy, ice hockey, basketball, squash, racquetball, running Level 6 Recreational sports- tennis and badminton, handball, racquetball, down-hill skiing, jogging at least 5 times per week Level 5 Work- heavy labor (construction, etc.)

Competitive sports- cycling, cross-country skiing,

Recreational sports- jogging on uneven ground at least twice weekly Level 4 Work- moderately heavy labor (e.g. truck driving, etc.) Level 3 Work- light labor (nursing, etc.) Level 2 Work- light labor

Walking on uneven ground possible, but impossible to back pack or hike Level 1 Work- sedentary (secretarial, etc.) Level 0 Sick leave or disability pension because of knee problems

Y Tegner and J Lysolm. Rating Systems in the Evaluation of Knee Ligament Injuries. Clinical Orthopedics and Related Research. Vol. 198: 43-49, 1985.

APPROVED BY Assigned Version Date: 09/05/2017 UNIVERSITY OF TOLEDO IRB

UT IRB# 201990

Godin Leisure-Time Exercise Questionnaire

INSTRUCTIONS

In this excerpt from the Godin Leisure-Time Exercise Questionnaire, the individual is asked to complete a self-explanatory, brief four-item query of usual leisure-time exercise habits.

CALCULATIONS

For the first question, weekly frequencies of strenuous, moderate, and light activities are multiplied by nine, five, and three, respectively. Total weekly leisure activity is calculated in arbitrary units by summing the products of the separate components, as shown in the following formula:

Weekly leisure activity score = (9 × Strenuous) + (5 × Moderate) + (3 × Light)

The second question is used to calculate the frequency of weekly leisure-time activities pursued “long enough to work up a sweat“ (see questionnaire).

EXAMPLE

Strenuous = 3 times/wk

Moderate = 6 times/wk

Light = 14 times/wk

Total leisure activity score = (9 × 3) + (5 × 6) + (3 × 14) = 27 + 30 + 42 = 99

Godin, G., Shephard, R. J.. (1997) Godin Leisure-Time Exercise Questionnaire. Medicine and Science in Sports and Exercise. 29 June Supplement: S36-S38.

Assigned Version Date: 09/05/2017 APPROVED BY UNIVERSITY OF TOLEDO IRB

UT IRB# 201990

Godin Leisure-Time Exercise Questionnaire

1. During a typical 7-Day period (a week), how many times on the average do you do the following kinds of exercise for more than 15 minutes during your free time (write on each line the appropriate number).

Times Per Week a) STRENUOUS EXERCISE (HEART BEATS RAPIDLY) ______(e.g., running, jogging, hockey, football, soccer, squash, basketball, cross country skiing, judo, roller skating, vigorous swimming, vigorous long distance bicycling)

b) MODERATE EXERCISE (NOT EXHAUSTING) ______(e.g., fast walking, baseball, tennis, easy bicycling, volleyball, badminton, easy swimming, alpine skiing, popular and folk dancing)

c) MILD EXERCISE (MINIMAL EFFORT) ______(e.g., yoga, archery, fishing from river bank, bowling, horseshoes, golf, snow-mobiling, easy walking)

2. During a typical 7-Day period (a week), in your leisure time, how often do you engage in any regular activity long enough to work up a sweat (heart beats rapidly)?

OFTEN SOMETIMES NEVER/RARELY 1. 2. 3.

Assigned Version Date: 09/05/2017 APPROVED BY UNIVERSITY OF TOLEDO IRB

UT IRB# 201990

Assigned Version Date: 09/05/2017 APPROVED BY UNIVERSITY OF TOLEDO IRB

Therapy Evaluation Form We would like you to indicate below how much you believe, right now, that the therapy you are receiving will help to improve your lifestyle / functioning. Belief usually has two aspects to it: (1) what one thinks will happen and (2) what one feels will happen. Sometimes these are similar; sometimes they are different. Please answer the questions below. In the first set, answer in terms of what you think. In the second set answer in terms of what you really and truly feel. We do not want your course convenors to ever see these ratings, so please keep the sheet covered when you are done. Set I 1. At this point, how logical does the course offered to you seem?

1 2 3 4 5 6 7 8 9 not at s omewhat logical v ery all logical l ogical

2. At this point, how successfully do you think this course will be in raising the quality of your functioning?

1 2 3 4 5 6 7 8 9 not at s omewhat useful v ery all useful u seful

3. How confident would you be in recommending this course to a friend who experiences similar problems? 1 2 3 4 5 6 7 8 9 none at S omewhat confident v ery all confident c onfident

4. By the end of the course, how much improvement in your functioning do you think will occur?

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Set II For this set, close your eyes for a few moments, and try to identify what you really feel about the course and its likely success. Then answer the following questions.

1. At this point, how much do you really feel that the course will help you to improve your functioning? 1 2 3 4 5 6 7 8 9 not somewhat very at all much

2. By the end of the course, how much improvement in your functioning do you really feel will occur?

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Data Collection Forms

FES Study Data Collection Form

Subject Number: ______Pre / Post Date: ______

Demographics

Age: ______

Mass: ______

Height: ______

Dominant Limb: ______/ Test Limb: ______

Questionnaire’s

Tegner: ______

Godin Leisure: ______

Hip Abduction Strength

Moment Arm (cm): ______

Trial 1: ______Trial 2: ______Trial 3: ______

Single Leg Squat (FPPA)

Trial 1: ______Trial 2: ______Trial 3: ______Trial 4: ______Trial 5: ______

VAS During SLS: ______

Physical Activity Tracking

Subject Number:______

Days Provide details on any exercise completed on your own outside of the research study (such as type, duration, etc) Please complete this for every day between the first data collection and last data collection.

Strength Training Session Collection Sheet

Subject Number: ______

Session 1 Session 2 Session 3 Session 4 Session 5 Session 6

Date and Time

FES Amplitude

Specific Testing Protocol

Setup and Procedures

I. Dynamic Knee Valgus (DKV) Screening Procedure a. Prior to enrollment potential subjects are to be screened for DKV b. Potential subjects will complete three single leg squats c. Researcher will assess position of the patella relative to great toe i. Eligible if patella is medial to the great toe for two out of three squats d. If found eligible, subject will be enrolled in study

II. Noraxon MR3 Electromyography (EMG) Software Setup a. Open Noraxon MR3 software b. Connect Noraxon Desk Receiver c. Select myoMuscle module d. Input/select subject information e. Select proper configuration for EMG collection i. Channel -> EMG 1 -> Glut. Med. (Rt./Lt.) f. Select “Start Measure” g. Select “Record” h. Measure five trials of GMed MVIC during strength testing i. Add a marker for each strength measurement trial j. Select “Stop” once trials have concluded k. Select “Save” i. Select “Save & View” ii. Select “Report” 1. Select “Average Activation Pattern Report” iii. Under “Select Channels” 1. “Body Side” a. “Rt./Lt. Glut. Med.” iv. Select “Next” v. Select “By Markers” vi. Select “Every Interval with Event” vii. Select “Set” viii. Select “Next” l. Select “Export Report” i. Select “Excel” ii. Save as “Subject_00”

III. Subject Preparation for EMG / Handheld Dynamometry (HHD) a. Situate subject on treatment table in side-lying position b. Identify the GMed belly during manually resisted hip abduction contraction

c. Identify midpoint of GMed between most superior portion of posterior iliac crest and greater trochanter of femur (Figure 1) i. Shave the area ii. Debride skin with gauze or abrasive pad iii. Clean with alcohol swab d. Place wireless EMG bar electrode over cleaned area i. Placed in parallel with muscle fiber orientation e. Connect leads to EMG electrodes f. Affix wireless unit nearby via double-sided adhesive g. Prepare subject for concomitant EMG and HHD data collection h. Once EMG setup is complete proceed to strength testing i. Zero-out Microfet 2 MMT HHD before testing i. Set output value to kilograms j. Situate subject on treatment table in side-lying position (Figure 2a) k. Place a pillow between the subject’s legs so the limb of interest may be abducted approximately 10° i. Measured in respect to a line connecting anterior superior iliac spines l. One strap is to be applied proximal to the iliac crest for trunk stabilization i. Secured around subject and underneath table m. Second strap placed 5cm proximal to lateral knee joint axis of rotation i. Moment arm distance measured in respect to hip axis of rotation to location for HHD ii. Secured around subject and underneath table n. Center of HHD placed 5cm proximal to lateral knee joint (Figure 2b) i. Distance measured in respect to hip axis of rotation o. HHD placed between strap and limb p. Subjects limb placed in slightly extended and externally rotated position q. Confirm appropriate setup and begin testing r. Testing will begin s. Investigator will stabilize HHD during trial and provide subject with verbal cues for length of contraction and initiation of contraction t. Subject will begin one practice trial u. Subject will then begin three experimental trials i. Maximal force applied for five seconds ii. 15 seconds of rest between trials v. Collect and record HHD data on subject data collection sheet i. Peak value recorded in kilograms w. Save EMG data file (Subject_00) and remove electrodes and wireless unit from subject

IV. Inertial Measurement Unit (IMU) / EMG Software Setup a. Open Noraxon MR3 software b. Connect myoMotion receiver via USB to computer c. Select myoMotion/myoMuscle module d. Input subject information

e. Select pre-made (by research team) configuration for IMU and EMG collection i. Configuration settings standardized to subject height f. Apply IMU sensors to subject on pelvis, middle 1/3 lateral shank, and middle 1/3 lateral thigh of test limb (Figure 3) i. EMG will have remained in place from strength testing g. Select “Start Measure” button h. Select “Calibrate” and have the subject assume the ‘Standing Straight’ calibration position i. Once calibrated prepare subject for task and select “Record” j. After the test activity has been completed select “Stop” k. Select “Save” i. Select “Save & View” l. Select “Report” to view the subject data i. IMU Report setup 1. Under the “myoMotion Reports” tab select “myoMotion ROM Report” 2. Select “OK” 3. The software will prompt you to view the ‘Select Channels’ tab, then choose the body side of interest 4. Select “Next” 5. Select “Min/Max by trigger channel” then select “Min to Max” a. Ensure the channel of interest (LT/RT Knee Flexion) is selected from the drop down 6. Select “Next” a. View the “myoMotion ROM Report” ii. EMG Report setup 1. Select “Report” a. Select “Average Activation Pattern Report” 2. Under “Select Channels” a. “Body Side” i. “Rt./Lt. Glut. Med.” 3. Select “Next” 4. Select “By Markers” 5. Select “Every Other Interval” 6. Select “Set” a. Select “Next” iii. Under “Output Options” 1. Select “Export Report” 2. Select “Excel” from drop down 3. Save IMU/EMG Report as “Subject_00”

V. IMU / Frontal Plane Projection Angle (FPPA) Setup a. Performed following strength/EMG testing b. EMG will remain on subject for single-leg squatting tasks

c. IMU’s placed on pelvis, middle 1/3 lateral thigh, and middle 1/3 lateral shank of test limb (Figure 3) i. Dominant limb identified by which limb the subject would use to kick a ball ii. Follow Section II for IMU software setup procedure d. One camera is situated on a tripod perpendicular to frontal plane 2m anterior to subject (Figure 4) i. Height of tripod in line with knee joint e. Second camera situated on a tripod perpendicular to sagittal plane 2m lateral to subject (Figure 4) i. Height of tripod in line with knee joint f. Retroreflective markers applied to anatomical locations i. Anterior superior iliac spine ii. Midpoint between femoral condyles iii. Anterior talocrural joint g. Turn on high speed camera by pressing “Prev. and/or Next” i. Cycle through menu using “Next” ii. Select “Photo” function iii. Press “Record” when ready to record subject image h. One image captured with subject standing still in single leg stance for normalization i. Subjects will then be introduced to single leg squat j. Practice period will be initiated i. Audible feedback given to subject from investigator to ensure depth beyond 60 and proper form ii. Rate of 15 squats per minute iii. Squats will last 5 seconds’ total k. Repeat ‘Step e.’ (camera setup prior to collection period) i. Cycle through menu using “Next” ii. Select “Movie” function iii. Press “Record” when ready to record collection period l. Collection period will begin i. Five squats will take place at selected speed ii. Squat successful if balance, speed and depth maintained iii. One minute of rest between trials m. In Noraxon MR3 software, a marker will be placed at the start of single leg squat and at the end n. If trials are unsuccessful, trial repeated o. Upon completion, subjects will complete a visual analog pain scale to asses any pain during task p. Save and record data/files (“Subject_00”) i. Remove IMU sensors, retroreflective markers, and EMG electrodes from subject

VI. ImageJ Setup / FPPA Data Processing a. Open ImageJ software

b. Open subject sing-leg stance image c. Open subject video file i. Identify greatest depth of squat in three of five squats d. Save subject frames for FPPA measurement i. Select “Open” and open subject image file ii. Select angle tool iii. Identify and “click” on proximal marker iv. Identify and “click” on middle marker v. Identify and “click” on distal marker vi. Select “Analyze” -> “Measure” vii. A measurement angle out of 180 will appear viii. Subtract given measurement from 180 in order to get FPPA ix. Input FPPA measurement into data collection sheet for subject x. Repeat Steps ‘i-ix’ for two additional frames xi. Average of the three frames of interest will be saved e. Close ImageJ

VII. Functional Electrical Stimulation (FES) Setup a. Identify superior portion of GMed by palpating superior portion of posteriro iliac crest (Figure 5b) b. Apply two 2x2” self-adhesive electrodes to this location c. Identify inferior portion of GMed by palpating greater trochanter of femur d. Apply two 2x2” self-adhesive electrodes to this location e. Turn on Compex Wireless USA Muscle Stimulator (Compex USA: Vista, CA) f. Use arrows to select “Endurance” (Figure 5a) i. Cycle through the placement options and select the glutes ii. Hit right arrow iii. Hit right arrow again to select “1st Use” g. Turn on wireless module by hitting the power button i. Select right arrow to advance h. Prepare subject for first exercise i. Situate subject in exercise position j. Press up arrow to start -> training period will begin on stimulator i. **Sham setup will be identical, but output will only be set to 1mA** k. Increase amplitude with up arrow to elicit a strong, but comfortable contraction l. Progress subject through resistance training protocol m. Once protocol has been completed i. Remove electrodes from subject ii. Remove electrodes from wireless modules iii. Place electrodes on backing n. Turn off wireless stimulator

VIII. Resistance Training Protocol

a. Protocol to be completed 3x per week for 2-weeks b. Exercise tasks will be completed for 3 sets of 10 repetitions c. Speed of each exercise standardized via metronome to 4-second movement i. 2-seconds of concentric contraction ii. 2-seconds of eccentric contraction d. Subjects will receive FES or Sham intervention in accordance with Section VII: Steps a-o e. Subjects will complete four exercises i. Side-lying hip abduction 1. Subject situated on treatment table in side-lying position 2. Both limbs in full extension with a neutral position 3. Weight applied to distal limb of interest 4. Subject will abduct the hip to 30 a. Instructed to slowly raise and lower 5. Investigator will provide verbal cues if necessary ii. Seated hip external rotation 1. Subject situated in a short-seated position 2. A theraband will be secured around the distal limb of interest 3. Subject will be instructed to externally rotate their hip against resistance applied by athletic trainer a. Instructed to slowly externally rotate and return to neutral 4. Investigator will provide verbal cues if necessary iii. Lateral step-down 1. Subjects will be situated standing on their dominant on a step that is 10% of their height 2. Subject will hold their non-dominant limb in full extension and ankle dorsiflexion 3. Subjects will lower themselves slowly until their heel comes into contact with the ground 4. Subject will concentrically contract and return to the starting position 5. Investigator will provide verbal cues if necessary iv. Pelvic drop task 1. Subjects will be situated standing on their dominant on a step that is 10% of their height 2. Subjects will lower their hip towards the ground and then raise their hip towards the ceiling 3. Investigator will provide verbal cues if necessary f. Training program compliance will be recorded by the research team for the 2-week period in a journal i. The following will be included 1. Session date/time 2. Exercises completed

3. FES amplitude for intervention group

Figure 1 – EMG Placement

Figure 1. Wireless EMG electrode placed midway between greater trochanter and most superior portion of posterior iliac crest

Figure 2 – HHD Setup

Figure 2a. Subject position; slight extension and external rotation

Figure 2b. HHD Placed 5cm from joint line

Knee Joint

Figure 3 – IMU/Marker Placement

Figure 4 – FPPA Camera Setup

Figure 5 – Compex Wireless Stimulator Setup

Figure 5a. Compex setup

procedure

Figure 5b. Compex electrode setup

Appendix D

Additional Results

Baseline anthropometric, subjective, and objective characteristics Demographics FES (n = 11) Sham (n = 11) p-value Age, yrs 21.6±1.0 22.0±1.7 .457 Height, m 1.7±0.02 1.6±0.08 .137 Mass, kg 76.7±16.5 77.0±21.6 .977 Sex 11F 11F Activity level (Godin) 44.9±25.3 50.6±26.9 .613 Activity level (Tegner) 5.7±1.1 5.9±1.2 .718 Yrs= Years, m=meters, kg=kilograms

Dynamic Single Limb Control (FPPA) 30 p= .006 p= .012

0 FES Sham

Pre Post

Credibility & Expectancy Questionairre 30 p= .120 p=.045 25

0 Credibility Expectancy

FES Sham

Descriptive Statistics

Std. N Minimum Maximum Mean Deviation Skewness Kurtosis Std. Std. Statistic Statistic Statistic Statistic Statistic Statistic Error Statistic Error

Age 22 19.00 25.00 21.8636 1.39029 .266 .491 .522 .953

Mass 22 44.70 132.00 76.9045 18.83466 .992 .491 2.329 .953

Height 22 1.57 1.83 1.6868 .06863 -.225 .491 -.573 .953

TestLimb 22 1.00 2.00 1.4545 .50965 .196 .491 -2.168 .953

TestGroup 22 1.00 2.00 1.5000 .51177 .000 .491 -2.211 .953

Tegner 22 3.00 7.00 5.8182 1.13961 -1.309 .491 1.769 .953

Godin 22 10.00 105.00 47.7727 25.67736 .991 .491 .673 .953

HipTorque_Pre 22 .38 1.02 .7198 .18183 -.051 .491 -1.048 .953

Hip_MVIC_EMG_Pre 22 16.53 251.00 84.9091 62.16403 1.536 .491 1.726 .953

Hip_SLS_EMG_Pre 22 21.45 128.07 58.4956 26.88646 .715 .491 .524 .953

FPPA_Pre 22 6.62 31.45 16.2083 7.24050 .510 .491 -.783 .953

VAS_Pre 22 .00 3.00 .3055 .76257 2.871 .491 8.019 .953

Hip_Torque_Post 22 .40 1.09 .7611 .16806 -.360 .491 -.032 .953

HIP_MVIC_EMG_Post 22 15.30 160.67 78.5576 43.50239 .398 .491 -1.273 .953

Hip_SLS_EMG_Post 22 3.92 67.28 41.2581 18.67197 -.481 .491 -.743 .953

FPPA_Post 22 -3.30 22.75 10.2262 6.66734 -.290 .491 .027 .953

VAS_Post 22 .00 1.00 .0764 .23227 3.581 .491 13.088 .953

Valid N (listwise) 22

Descriptive Statistics

TestGroup Mean Std. Deviation N

HipTorque_Pre 1.00 .7596 .18767 11 2.00 .6800 .17530 11 Total .7198 .18183 22 Hip_Torque_Post 1.00 .7634 .18813 11 2.00 .7589 .15461 11 Total .7611 .16806 22 Hip_MVIC_EMG_Pre 1.00 101.7818 80.40968 11 2.00 68.0364 31.98654 11 Total 84.9091 62.16403 22 HIP_MVIC_EMG_Post 1.00 72.6242 41.70306 11 2.00 84.4909 46.44961 11 Total 78.5576 43.50239 22 Hip_SLS_EMG_Pre 1.00 57.2380 30.96633 11 2.00 59.7532 23.57240 11 Total 58.4956 26.88646 22 Hip_SLS_EMG_Post 1.00 43.5802 16.38125 11 2.00 38.9360 21.25891 11 Total 41.2581 18.67197 22 FPPA_Pre 1.00 16.1330 8.62610 11 2.00 16.2836 5.97243 11 Total 16.2083 7.24050 22 FPPA_Post 1.00 9.1346 8.03687 11 2.00 11.3177 5.11270 11 Total 10.2262 6.66734 22 VAS_Pre 1.00 .0655 .14740 11 2.00 .5455 1.03573 11 Total .3055 .76257 22 VAS_Post 1.00 .0500 .14947 11

2.00 .1027 .29903 11 Total .0764 .23227 22

Multivariate Testsa Hypothesis Error Noncent. Observed Effect Value F df df Sig. Parameter Powerc Between Intercept Pillai's Trace .992 422.890b 5.000 16.000 .000 2114.450 1.000 Subjects Wilks' .008 422.890b 5.000 16.000 .000 2114.450 1.000 Lambda Hotelling's 132.153 422.890b 5.000 16.000 .000 2114.450 1.000 Trace Roy's Largest 132.153 422.890b 5.000 16.000 .000 2114.450 1.000 Root TestGroup Pillai's Trace .277 1.228b 5.000 16.000 .341 6.142 .324

Wilks' .723 1.228b 5.000 16.000 .341 6.142 .324 Lambda Hotelling's .384 1.228b 5.000 16.000 .341 6.142 .324 Trace

Roy's Largest .384 1.228b 5.000 16.000 .341 6.142 .324 Root Within Time Pillai's Trace .715 8.042b 5.000 16.000 .001 40.208 .993 Subjects Wilks' .285 8.042b 5.000 16.000 .001 40.208 .993 Lambda Hotelling's 2.513 8.042b 5.000 16.000 .001 40.208 .993 Trace Roy's Largest 2.513 8.042b 5.000 16.000 .001 40.208 .993 Root Time * Pillai's Trace .339 1.639b 5.000 16.000 .207 8.195 .428 TestGroup Wilks' .661 1.639b 5.000 16.000 .207 8.195 .428 Lambda Hotelling's .512 1.639b 5.000 16.000 .207 8.195 .428 Trace Roy's Largest .512 1.639b 5.000 16.000 .207 8.195 .428 Root a. Design: Intercept + TestGroup Within Subjects Design: Time b. Exact statistic

c. Computed using alpha = .05

Multivariatea,b Hypothesis Noncent. Observed Within Subjects Effect Value F df Error df Sig. Parameter Powerd Time Pillai's Trace .715 8.042c 5.000 16.000 .001 40.208 .993 Wilks' Lambda .285 8.042c 5.000 16.000 .001 40.208 .993

Hotelling's 2.513 8.042c 5.000 16.000 .001 40.208 .993 Trace Roy's Largest 2.513 8.042c 5.000 16.000 .001 40.208 .993 Root Time * Pillai's Trace .339 1.639c 5.000 16.000 .207 8.195 .428

TestGroup Wilks' Lambda .661 1.639c 5.000 16.000 .207 8.195 .428 Hotelling's .512 1.639c 5.000 16.000 .207 8.195 .428 Trace Roy's Largest .512 1.639c 5.000 16.000 .207 8.195 .428 Root a. Design: Intercept + TestGroup Within Subjects Design: Time b. Tests are based on averaged variables. c. Exact statistic d. Computed using alpha = .05 Tests of Within-Subjects Effects

Univariate Tests

Type III Noncent. Sum of Mean Paramete Observe Source Measure Squares df Square F Sig. r d Powera

Time Hip_Torque Sphericity .14 .019 1 .019 2.266 2.266 .300 Assumed 8 Greenhouse .14 .019 1.000 .019 2.266 2.266 .300 -Geisser 8 Huynh-Feldt .14 .019 1.000 .019 2.266 2.266 .300 8

Lower- .14 .019 1.000 .019 2.266 2.266 .300 bound 8

Hip_MVIC_EM Sphericity .55 443.759 1 443.759 .367 .367 .089 G Assumed 2

Greenhouse .55 443.759 1.000 443.759 .367 .367 .089 -Geisser 2 Huynh-Feldt .55 443.759 1.000 443.759 .367 .367 .089 2 Lower- .55 443.759 1.000 443.759 .367 .367 .089 bound 2 SLS_EMG Sphericity 3268.45 10.54 .00 3268.450 1 10.545 .870 Assumed 0 5 4 Greenhouse 3268.45 10.54 .00 3268.450 1.000 10.545 .870 -Geisser 0 5 4

Huynh-Feldt 3268.45 10.54 .00 3268.450 1.000 10.545 .870 0 5 4 Lower- 3268.45 10.54 .00 3268.450 1.000 10.545 .870 bound 0 5 4

FPPA Sphericity 21.00 .00 393.648 1 393.648 21.004 .992 Assumed 4 0 Greenhouse 21.00 .00 393.648 1.000 393.648 21.004 .992 -Geisser 4 0 Huynh-Feldt 21.00 .00 393.648 1.000 393.648 21.004 .992 4 0 Lower- 21.00 .00 393.648 1.000 393.648 21.004 .992 bound 4 0 VAS Sphericity .11 .577 1 .577 2.802 2.802 .357 Assumed 0

Greenhouse .11 .577 1.000 .577 2.802 2.802 .357 -Geisser 0 Huynh-Feldt .11 .577 1.000 .577 2.802 2.802 .357 0 Lower- .11 .577 1.000 .577 2.802 2.802 .357 bound 0 Time * Hip_Torque Sphericity .18 .016 1 .016 1.872 1.872 .256 TestGroup Assumed 6 Greenhouse .18 .016 1.000 .016 1.872 1.872 .256 -Geisser 6 Huynh-Feldt .18 .016 1.000 .016 1.872 1.872 .256 6

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Lower- .18 .016 1.000 .016 1.872 1.872 .256 bound 6 Hip_MVIC_EM Sphericity 5721.28 .04 5721.280 1 4.729 4.729 .544 G Assumed 0 2 Greenhouse 5721.28 .04 5721.280 1.000 4.729 4.729 .544 -Geisser 0 2 Huynh-Feldt 5721.28 .04 5721.280 1.000 4.729 4.729 .544 0 2 Lower- 5721.28 .04 5721.280 1.000 4.729 4.729 .544 bound 0 2 SLS_EMG Sphericity .50 140.961 1 140.961 .455 .455 .098 Assumed 8 Greenhouse .50 140.961 1.000 140.961 .455 .455 .098 -Geisser 8 Huynh-Feldt .50 140.961 1.000 140.961 .455 .455 .098 8 Lower- .50 140.961 1.000 140.961 .455 .455 .098 bound 8 FPPA Sphericity .44 11.360 1 11.360 .606 .606 .115 Assumed 5 Greenhouse .44 11.360 1.000 11.360 .606 .606 .115 -Geisser 5 Huynh-Feldt .44 11.360 1.000 11.360 .606 .606 .115 5 Lower- .44 11.360 1.000 11.360 .606 .606 .115 bound 5 VAS Sphericity .13 .502 1 .502 2.437 2.437 .318 Assumed 4 Greenhouse .13 .502 1.000 .502 2.437 2.437 .318 -Geisser 4 Huynh-Feldt .13 .502 1.000 .502 2.437 2.437 .318 4 Lower- .13 .502 1.000 .502 2.437 2.437 .318 bound 4 Error(Time Hip_Torque Sphericity .166 20 .008 ) Assumed

Greenhouse 20.00 .166 .008 -Geisser 0

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Huynh-Feldt 20.00 .166 .008 0

Lower- 20.00 .166 .008 bound 0 Hip_MVIC_EM Sphericity 24198.34 1209.91 20 G Assumed 2 7

Greenhouse 24198.34 20.00 1209.91 -Geisser 2 0 7

Huynh-Feldt 24198.34 20.00 1209.91 2 0 7

Lower- 24198.34 20.00 1209.91 bound 2 0 7

SLS_EMG Sphericity 6198.893 20 309.945 Assumed Greenhouse 20.00 6198.893 309.945 -Geisser 0 Huynh-Feldt 20.00 6198.893 309.945 0 Lower- 20.00 6198.893 309.945 bound 0 FPPA Sphericity 374.827 20 18.741 Assumed Greenhouse 20.00 374.827 18.741 -Geisser 0 Huynh-Feldt 20.00 374.827 18.741 0

Lower- 20.00 374.827 18.741 bound 0 VAS Sphericity 4.120 20 .206 Assumed Greenhouse 20.00 4.120 .206 -Geisser 0 Huynh-Feldt 20.00 4.120 .206 0

Lower- 20.00 4.120 .206 bound 0 a. Computed using alpha = .05

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Tests of Within-Subjects Contrasts Type III Sum of Mean Noncent. Observed Source Measure Time Squares df Square F Sig. Parameter Powera Time Hip_Torque Linear .019 1 .019 2.266 .148 2.266 .300

Hip_MVIC_EMG Linear 443.759 1 443.759 .367 .552 .367 .089

SLS_EMG Linear 3268.450 1 3268.450 10.545 .004 10.545 .870

FPPA Linear 393.648 1 393.648 21.004 .000 21.004 .992

VAS Linear .577 1 .577 2.802 .110 2.802 .357 Time * Hip_Torque Linear .016 1 .016 1.872 .186 1.872 .256 TestGroup Hip_MVIC_EMG Linear 5721.280 1 5721.280 4.729 .042 4.729 .544 SLS_EMG Linear 140.961 1 140.961 .455 .508 .455 .098 FPPA Linear 11.360 1 11.360 .606 .445 .606 .115 VAS Linear .502 1 .502 2.437 .134 2.437 .318 Error(Time) Hip_Torque Linear .166 20 .008

Hip_MVIC_EMG Linear 24198.342 20 1209.917

SLS_EMG Linear 6198.893 20 309.945

FPPA Linear 374.827 20 18.741

VAS Linear 4.120 20 .206 a. Computed using alpha = .05

Levene's Test of Equality of Error Variancesa F df1 df2 Sig. HipTorque_Pre .092 1 20 .764 Hip_Torque_Post .772 1 20 .390 Hip_MVIC_EMG_Pre 11.781 1 20 .003 HIP_MVIC_EMG_Post .278 1 20 .604 Hip_SLS_EMG_Pre .227 1 20 .639 Hip_SLS_EMG_Post 1.541 1 20 .229 FPPA_Pre 1.101 1 20 .307 FPPA_Post 1.427 1 20 .246 VAS_Pre 13.997 1 20 .001 VAS_Post .968 1 20 .337 Tests the null hypothesis that the error variance of the dependent variable is equal across groups. a. Design: Intercept + TestGroup Within Subjects Design: Time

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Tests of Between-Subjects Effects Transformed Variable: Average Type III Sum of Mean Noncent. Observed Source Measure Squares df Square F Sig. Parameter Powera Intercept Hip_Torque 24.125 1 24.125 443.954 .000 443.954 1.000

Hip_MVIC_EMG 293934.862 1 293934.862 65.569 .000 65.569 1.000

SLS_EMG 109458.800 1 109458.800 135.555 .000 135.555 1.000

FPPA 7686.602 1 7686.602 94.125 .000 94.125 1.000

VAS 1.604 1 1.604 4.038 .058 4.038 .481 TestGroup Hip_Torque .019 1 .019 .357 .557 .357 .088 Hip_MVIC_EMG 1316.374 1 1316.374 .294 .594 .294 .081 SLS_EMG 12.464 1 12.464 .015 .902 .015 .052 FPPA 14.977 1 14.977 .183 .673 .183 .069 VAS .780 1 .780 1.965 .176 1.965 .267 Error Hip_Torque 1.087 20 .054

Hip_MVIC_EMG 89657.332 20 4482.867

SLS_EMG 16149.690 20 807.485

FPPA 1633.279 20 81.664

VAS 7.942 20 .397 a. Computed using alpha = .05

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Estimated Marginal Means 1. TestGroup * Time 95% Confidence Interval

Measure TestGroup Time Mean Std. Error Lower Bound Upper Bound Hip_Torque 1.00 1 .760 .055 .645 .874 2 .763 .052 .655 .872 2.00 1 .680 .055 .566 .794

2 .759 .052 .651 .867 Hip_MVIC_EMG 1.00 1 101.782 18.450 63.296 140.268 2 72.624 13.309 44.863 100.386 2.00 1 68.036 18.450 29.550 106.522 2 84.491 13.309 56.729 112.253 SLS_EMG 1.00 1 57.238 8.297 39.930 74.546 2 43.580 5.722 31.644 55.516 2.00 1 59.753 8.297 42.446 77.061 2 38.936 5.722 27.000 50.872 FPPA 1.00 1 16.133 2.237 11.467 20.799 2 9.135 2.031 4.898 13.371 2.00 1 16.284 2.237 11.618 20.950 2 11.318 2.031 7.082 15.554 VAS 1.00 1 .065 .223 -.400 .531

2 .050 .071 -.099 .199 2.00 1 .545 .223 .080 1.011 2 .103 .071 -.046 .251

Pairwise Comparisons

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95% Confidence Interval Mean for Differencea (I) (J) Difference (I- Std. Lower Upper Measure TestGroup TestGroup J) Error Sig.a Bound Bound Hip_Torque 1.00 2.00 .042 .070 .557 -.105 .189 2.00 1.00 -.042 .070 .557 -.189 .105 Hip_MVIC_EMG 1.00 2.00 10.939 20.187 .594 -31.171 53.050 2.00 1.00 -10.939 20.187 .594 -53.050 31.171 SLS_EMG 1.00 2.00 1.064 8.568 .902 -16.808 18.937 2.00 1.00 -1.064 8.568 .902 -18.937 16.808 FPPA 1.00 2.00 -1.167 2.725 .673 -6.850 4.517 2.00 1.00 1.167 2.725 .673 -4.517 6.850 VAS 1.00 2.00 -.266 .190 .176 -.663 .130 2.00 1.00 .266 .190 .176 -.130 .663 Based on estimated marginal means a. Adjustment for multiple comparisons: Least Significant Difference (equivalent to no adjustments).

Multivariate Tests Noncent. Observed Value F Hypothesis df Error df Sig. Parameter Powerb Pillai's trace .277 1.228a 5.000 16.000 .341 6.142 .324 Wilks' lambda .723 1.228a 5.000 16.000 .341 6.142 .324 Hotelling's trace .384 1.228a 5.000 16.000 .341 6.142 .324 Roy's largest .384 1.228a 5.000 16.000 .341 6.142 .324 root Each F tests the multivariate effect of TestGroup. These tests are based on the linearly independent pairwise comparisons among the estimated marginal means. a. Exact statistic b. Computed using alpha = .05

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Univariate Tests Sum of Mean Noncent. Observed Measure Squares df Square F Sig. Parameter Powera Hip_Torque Contrast .010 1 .010 .357 .557 .357 .088 Error .543 20 .027 Hip_MVIC_EMG Contrast 658.187 1 658.187 .294 .594 .294 .081 Error 44828.666 20 2241.433 SLS_EMG Contrast 6.232 1 6.232 .015 .902 .015 .052 Error 8074.845 20 403.742 FPPA Contrast 7.488 1 7.488 .183 .673 .183 .069 Error 816.639 20 40.832 VAS Contrast .390 1 .390 1.965 .176 1.965 .267

Error 3.971 20 .199 The F tests the effect of TestGroup. This test is based on the linearly independent pairwise comparisons among the estimated marginal means. a. Computed using alpha = .05

Estimates 95% Confidence Interval Measure Time Mean Std. Error Lower Bound Upper Bound

Hip_Torque 1 .720 .039 .639 .801 2 .761 .037 .685 .838 Hip_MVIC_EMG 1 84.909 13.046 57.695 112.123 2 78.558 9.411 58.927 98.188 SLS_EMG 1 58.496 5.867 46.257 70.734 2 41.258 4.046 32.818 49.698 FPPA 1 16.208 1.582 12.909 19.508 2 10.226 1.436 7.231 13.222 VAS 1 .305 .158 -.024 .634 2 .076 .050 -.029 .181

Pairwise Comparisons

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Mean 95% Confidence Interval for Difference (I- Differenceb Measure (I) Time (J) Time J) Std. Error Sig.b Lower Bound Upper Bound Hip_Torque 1 2 -.041 .027 .148 -.099 .016 2 1 .041 .027 .148 -.016 .099 Hip_MVIC_EMG 1 2 6.352 10.488 .552 -15.526 28.229 2 1 -6.352 10.488 .552 -28.229 15.526 SLS_EMG 1 2 17.238* 5.308 .004 6.165 28.310 2 1 -17.238* 5.308 .004 -28.310 -6.165 FPPA 1 2 5.982* 1.305 .000 3.259 8.705 2 1 -5.982* 1.305 .000 -8.705 -3.259 VAS 1 2 .229 .137 .110 -.056 .515

2 1 -.229 .137 .110 -.515 .056 Based on estimated marginal means *. The mean difference is significant at the .05 level. b. Adjustment for multiple comparisons: Least Significant Difference (equivalent to no adjustments).

Multivariate Tests Noncent. Observed Value F Hypothesis df Error df Sig. Parameter Powerb Pillai's trace .715 8.042a 5.000 16.000 .001 40.208 .993 Wilks' lambda .285 8.042a 5.000 16.000 .001 40.208 .993 Hotelling's trace 2.513 8.042a 5.000 16.000 .001 40.208 .993 Roy's largest 2.513 8.042a 5.000 16.000 .001 40.208 .993 root Each F tests the multivariate effect of Time. These tests are based on the linearly independent pairwise comparisons among the estimated marginal means. a. Exact statistic b. Computed using alpha = .05

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Correlations Difference_HipTo Difference_HipABD_ Difference_SLS_ Difference_F rque EMG EMG PPA Difference_HipTorqu Pearson e Correlati 1 .081 .100 .119 on Sig. (2- .719 .657 .599 tailed) N 22 22 22 22 Difference_HipABD_ Pearson EMG Correlati .081 1 -.532* .323 on Sig. (2- .719 .011 .143 tailed) N 22 22 22 22 Difference_SLS_EM Pearson G Correlati .100 -.532* 1 -.205 on Sig. (2- .657 .011 .360 tailed) N 22 22 22 22 Difference_FPPA Pearson Correlati .119 .323 -.205 1 on Sig. (2- .599 .143 .360 tailed)

N 22 22 22 22 *. Correlation is significant at the 0.05 level (2-tailed).

Paired Samples Statistics Mean N Std. Deviation Std. Error Mean Pair 1 FPPA_Pre 16.2083 22 7.24050 1.54368 FPPA_Post 10.2262 22 6.66734 1.42148

Paired Samples Correlations N Correlation Sig. Pair 1 FPPA_Pre & FPPA_Post 22 .622 .002

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Paired Samples Test

Paired Differences 95% Confidence Interval of the Std. Std. Error Difference Sig. (2- Mean Deviation Mean Lower Upper t df tailed) Pair FPPA_Pre - 5.98215 6.06462 1.29298 3.29325 8.67106 4.627 21 .000 1 FPPA_Post

Paired Samples Statistics Mean N Std. Deviation Std. Error Mean Pair 1 FPPA_Pre 16.1330 11 8.62610 2.60087 FPPA_Post 9.1346 11 8.03687 2.42321

Paired Samples Correlations N Correlation Sig. Pair 1 FPPA_Pre & FPPA_Post 11 .672 .023

Paired Samples Test

Paired Differences 95% Confidence Interval of the Std. Std. Error Difference Sig. (2- Mean Deviation Mean Lower Upper t df tailed) Pair FPPA_Pre - 6.99836 6.76733 2.04043 2.45201 11.54472 3.430 10 .006 1 FPPA_Post

Paired Samples Statistics Mean N Std. Deviation Std. Error Mean Pair 1 FPPA_Pre 16.2836 11 5.97243 1.80075 FPPA_Post 11.3177 11 5.11270 1.54154

Paired Samples Correlations N Correlation Sig. Pair 1 FPPA_Pre & FPPA_Post 11 .534 .090

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Paired Samples Test

Paired Differences 95% Confidence Interval of the Std. Std. Error Difference Sig. (2- Mean Deviation Mean Lower Upper t df tailed) Pair FPPA_Pre - 4.96594 5.40080 1.62840 1.33763 8.59425 3.050 10 .012 1 FPPA_Post VAS:

Paired Samples Statistics Mean N Std. Deviation Std. Error Mean Pair 1 VAS_Pre .3055 22 .76257 .16258 VAS_Post .0764 22 .23227 .04952

Paired Samples Test

Paired Differences 95% Confidence Interval of the Difference Std. Std. Error Sig. (2- Mean Deviation Mean Lower Upper t df tailed) Pair VAS_Pre - .22909 .66350 .14146 -.06509 .52327 1.619 21 .120 1 VAS_Post

CEQ: Descriptives 95% Confidence Interval for Mean Std. Std. Lower Upper N Mean Deviation Error Bound Bound Minimum Maximum

VAR00002 1.00 11 23.7273 2.28433 .68875 22.1926 25.2619 20.00 27.00 2.00 11 21.7273 3.37908 1.01883 19.4572 23.9974 15.00 26.00 Total 22 22.7273 2.99495 .63852 21.3994 24.0552 15.00 27.00 VAR00003 1.00 11 19.9964 3.82838 1.15430 17.4244 22.5683 12.18 25.36

2.00 11 15.8636 5.12663 1.54574 12.4195 19.3078 8.09 24.36

Total 22 17.9300 4.89570 1.04377 15.7594 20.1006 8.09 25.36

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ANOVA Sum of Squares df Mean Square F Sig. VAR00002 Between Groups 22.000 1 22.000 2.645 .120 Within Groups 166.364 20 8.318 Total 188.364 21 VAR00003 Between Groups 93.937 1 93.937 4.589 .045

Within Groups 409.389 20 20.469 Total 503.325 21

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Appendix E

Back Matter

Recommendations for Future Research

Future research is needed to examine the effects of a longer training program with superimposed electrical stimulation on GMed functional capacity. Secondly, we only used EMG to measure GMed activity during two tasks. Due to the multiple GMed fiber orientation and their differences in function, that may have minimized to assess a more complete assessment of gluteal function following the intervention. Focus on the posterior fibers of the GMed and superior fibers of the gluteus maximus should also be examined, due to their roles in controlling frontal plane and transverse motion. Lastly, it is currently unknown the optimal number of exercises required to improve muscle function. The study selected the four exercises included since previous literature has identified them to target the GMed muscle. It is unclear if more exercises would have resulted in differences within the study.

Additionally, the variable of trunk lean could be assessed by adding more markers to the subject’s torso. This would allow clinicians a better insight as to whether the DKV is being inhibited by alterations in trunk lean to compensate for lack of GMed’s control in frontal plane kinematics. Having a full biomechanical assessment would provide insight if the two groups altered their transverse motion, which may contribute to the demands of the GMed to control motion in that plane.

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NATA Abstract

The Effect of Functional Electrical Stimulation (FES) Applied to the Gluteus Medius During Resistance Training Robinson MR*, Norte G*, Murray A*, Glaviano N*: *The University of Toledo

Context: Gluteus medius (GMed) weakness is a common impairment for a variety of pathologies. Clinical presentation of GMed weakness during tasks like the single leg squat (SLS) is increased hip adduction, internal rotation, and knee valgus. It is essential to optimize the function of this muscle to prevent injury. Functional electrical stimulation (FES) is an emerging treatment to improve activation of impaired muscles. However, it has yet to be evaluated at improving GMed strength or squatting mechanics in females with dynamic knee valgus(DKV) Objective: The purpose of this study was to examine the effectiveness of a strengthening intervention with or without FES on GMed function, when assessed by strength, muscle activation, and frontal plane kinematics. Design: Randomized Controlled Single-Blinded Controlled Laboratory Trial. Setting: Laboratory. Patients or Other Participants: 22 healthy adult females (Age: 21.8±1.4yrs, Mass: 76.9±18.8kg, Height: 1.7±.1m) with DKV. Intervention(s): Participants were randomized to 2 resistance training groups; FES which administered a visible comfortable contraction of the GMed during therapeutic exercise, or sham treatment with no stimulation during exercise. The intervention was composed of 4 exercises: side-lying abduction, seated hip external rotation, lateral step down, pelvic drop task (3x10), 3 times a week for 2-weeks. Main Outcome Measure(s): All variables were tested pre and post- intervention. Hip abduction torque was assessed via HHD (Nm/kg), normalized GMed activity during SLS (percentage MVIC), and frontal plane projection angle (FPPA) during a SLS. Patient credibility and expectancy measures were collected with the Credibility and Expectancy Questionnaire (CEQ) to assess the intervention. Repeated measures ANOVA with Tukey’s post hoc testing was conducted eith significance of p<.05. Cohen’s d effect sizes and 95% confidence intervals were calculated. Results: Groups were similar at baseline for both demographics and all outcome measures. All participants completed all interventions sessions over the 2-week period. Both groups demonstrated improvements in their FPPA during a SLS at the conclusion of the intervention (FES:Pre-16.13±8.63,Post-9.13±8.04,p=.006;Sham:Pre-16.28±5.97,Post- 11.31±5.11,p=.012). No differences in hip abduction torque (FES:Pre-0.750.18,Post- 0.760.18 Nm/kg; Sham:Pre-0.680.17,Post-0.750.15 Nm/kg, p=.146) were seen. Additionally, there was no difference in SLS GMed activity (FES:Pre-57.23±30.97, Post- 43.58±16.38%;Sham:Pre-59.75±23.57, Post-38.94±21.26%, p=.176). Large effect sizes were found in FES group for FPPA (d=.84[-.03,1.71]). Sham group demonstrated a large

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effect size for SLS EMG post-intervention (FES:d=.55[-.3,1.4];Sham:d=.93[.05,1.81]). Values for credibility were similar between groups upon completion (FES:23.72.28;Sham:21.723.37;p=.120). However, expectancy was significantly greater in the FES group (FES:19.993.8;Sham:15.865.12;p=.045). Conclusions: Our findings imply that resistance training of 2-weeks with/without FES both elicited improvements in FPPA that exceeded the standard error of measure (3.2) during a SLS. However, it did not meet the smallest detectable difference (8.93) which may suggest implementing a longer FES strength training intervention for decreased FPPA measurements. Additionally, those in FES group had higher expectation which may lead to better patient reported outcomes. Word Count: 450

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Appendix F

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