I VALIDITY and RELIABILITY of HUMAC360 to MEASURE

VALIDITY AND RELIABILITY OF HUMAC360 TO MEASURE VELOCITY DURING BACK SQUAT AND BENCH PRESS

A thesis submitted to the Kent State University College of Education, Health, and Human Services in partial fulfillment of the requirements for the degree of Master of Science

Modesto A. Lebron

May 2021

Thesis written by

Modesto A. Lebron

B.S., Kent State University, 2019

Approved by

, Director, Master’s Thesis Committee Adam R. Jajtner

, Member, Master’s Thesis Committee Jacob E. Barkley

, Member, Master’s Thesis Committee J. Derek Kingsley

Accepted by

, Director, School of Health Sciences Ellen L. Glickman

, Dean, College of Education, Health and Human James C. Hannon Services

iii

LEBRON, MODESTO A., M.S., 2021 Health and Human Services

VALIDITY AND RELIABILITY OF HUMAC360 TO MEASURE VELOCITY DURING BACK SQUAT AND BENCH PRESS (97 pp.)

Director of Thesis: Adam R. Jajtner, Ph.D.

The purpose of this investigation will be to assess the validity and reliability of the HUMAC360 and its ability to measure velocity during submaximal loads for the barbell back squat and bench press. Twenty healthy men and women will be asked to report laboratory on three separate occasions, with at least 48 hours separating each visit. During Visit 1, anthropometrics will be obtained followed by a one-repetition maximum assessment for both the barbell back squat and bench press. During Visit 2 and Visit 3, participants will be asked to complete two sets of three repetitions for relative loads of 30, 50, 60 and 70% of their previously determined 1-RM, for the purpose of assessing velocity. To assess validity of the HUMAC 360, dependent T-tests will be used in comparison to the criterion Tendo unit. Additionally, relationships between these variables will be assessed by Pearson product- moment correlation. To assess reliability of the HUMAC360, dependent T-tests will be used to compare velocity data at each submaximal load from Visits 2 and 3. Additionally, test-retest reliability will be assessed using intraclass coefficients (ICC’s 3,1).

ACKNOWLEDGEMENTS

I would like to thank Dr. Adam Jajtner for his help and mentorship throughout this project. I would also like to thank my colleagues, friends, and family for their consistent support.

TABLE OF CONTENTS Page

ACKNOWLEDGEMENTS ...... iv

CHAPTER I. INTRODUCTION ...... 1 Specific Aims ...... 3

II. LITERATURE REVIEW ...... 5 Velocity-Based Training ...... 5 Velocity-Based Training Summery ...... 14 Load-Velocity Relationship ...... 15 Load-Velocity Relationship Summery ...... 20 Velocity Assessment Tools ...... 21 Velocity Assessment Tools Summery ...... 30

III. METHODS ...... 32 Experimental Approach ...... 32 Participants ...... 34 Procedures ...... 34 1-Repetition Maximum Assessment ...... 34 Velocity Assessment ...... 35 Statistical Analysis ...... 37

IV. FUTURE STUDY BACKGROUND ...... 38 Rationale ...... 38 Specific Aims ...... 41

V. FUTURE STUDY METHODS ...... 44 Participants ...... 44 Sample Size Estimates ...... 44 Experimental Approach ...... 45 Procedures ...... 48 Anthropometric Measures ...... 48 1-Repetition Maximum Assessment ...... 48 Velocity Assessment ...... 49 Velocity Curve Analysis ...... 50 Statistical Analysis ...... 51 Potential Limitations and Contingencies ...... 51 Potential Limitations ...... 51

Contingencies ...... 52 APPENDICES ...... 54 APPENDIX A. FUTURE STUDY ABSTRACT ...... 55 APPENDIX B. KENT STATE APPROVED IRB...... 58 APPENDIX C. INFORMED CONSENT ...... 76 APPENDIX D. MEDICAL HEALTH HISTORY QUESTIONNAIRE ...... 82 APPENDIX E. RECRUITMENT FLYER...... 87 APPENDIX F. RECRUITMENT SCRIPT ...... 89 REFERENCES ...... 91

CHAPTER I

INTRODUCTION

Resistance training is as an exercise method that is commonly employed to provide improvements in hypertrophy, maximal strength, and muscular power. Traditionally, load may be dictated as a percent of an individual’s one-repetition maximum (1-RM), known as percent- based training (PBT (Orange et al., 2020). Prior researchers have established that specific submaximal loads may correlate to a total number of repetitions completed before failure

(Mayhew et al., 1992). Although this method has been shown to improve strength and hypertrophy (Baker, Wilson, and Carlyon, 1994), PBT fails to allow for autoregulation.

Autoregulation is defined as the ability to increase or decrease load, with respect to performance within a specific training session. This may be necessary, as performance may vary between training sessions due to a variety of influences (Dankel et al., 2017, Leveritt & Abernethy, 1999,

Reilly & Piercy, 1994, Mann et al., 2016)), potentially requiring alteration of training load beyond the pre-prescribed intensity. Traditional autoregulation methods include rate of perceived exertion (RPE) and repetitions in reserve (RIR) (Shattock and Tee, 2020), however, there is an increasing popularity in velocity-based training (VBT).

Velocity-based training is an autoregulation method that uses movement velocity to dictate intensity (Dorrell et al., 2020). Various velocity measurements have been demonstrated to have a strong relationship (r2 ≥ 0.96) with relative loads (%1-RM), including mean velocity

(MV) (Pestana-Melero et al., 2018), mean propulsive velocity (MPV) (Gonzalez-Badillo &

Sanchez-Medina, 2010, Loturco et al., 2017), and mean concentric velocity (MCV) (Pestana-

Melero et al., 2018). As a result, utilizing movement velocity allows for an accurate estimation

2 of %1-RM, as well as maximal strength, as measured through 1-RM (Jidovtseff et al., 2011).

Therefore, velocity measurements may be used to detect fluctuations in maximal strength within and between training sessions (Dorrell et al, 2020, Orange et al., 2020). Gonzalez-Badillo and

Sanchez-Medina (2010) observed that a significant increase in maximal strength did not alter

MPV at specific %1-RM, indicating each %1-RM has a specific movement velocity range. As previously stated, velocity at specific %1-RM has high reliability, therefore, specific to an exercise, velocity ranges can be established for %1-RM utilizing estimations or specific load- velocity profiles (Jidovtseff et al., 2011). If movement velocity during an individual set varies significantly beyond an established range, load can be adjusted respectively for the subsequent sets using these load-velocity profiles.

Traditional PBT uses specific relative loads without any form of autoregulation which may ultimately result in excess training volume. Using VBT over a 6-week period has previously resulted in reduced total training volume while also resulting in similar or greater increases in maximal strength when compared to PBT (Dorell, Smith, and Gee, 2020).

Moreover, rugby athletes reported a reduction in RPE scores over the course of training (Orange et al., 2020). Real time feedback from VBT is objective and provides specific quantitative data allowing for more specific autoregulation of intensity during training, in comparison to RPE scales which provide more subjective feedback (Shattock and Tee, 2020). Shattock and Tee

(2020) observed that VBT over 6-week training blocks provided more favorable increases in maximal strength for the back squat (BS) and bench press (BP), in comparison to using category- ratio RPE and RIR scales. Velocity-based training has also been demonstrated to elicit more clear improvements in countermovement jump (CMJ) height, in comparison to traditional PBT

(Orange et al., 2020) and RPE autoregulation (Shattock and Tee, 2020). Furthermore, the use of

VBT has been demonstrated to provide significant improvements in performance variables such as CMJ height and load eliciting an arbitrary velocity of ~1.00 m·s-1 in under-16 and under-18 soccer athletes (Gonzelez-Badillo et al., 2015), suggesting a potential benefit to athletes with less resistance training experience.

To adequately assess movement velocity, the use of a valid and reliable velocity measurement device is a necessity. Previous investigations have assessed the validity and reliability of numerous velocity measurement devices, including linear position transducers

(Stock et al., 2011), inertial measurement units (Perez-Castillo et al., 2019), and optical motion capture systems (Perez-Castillo et al., 2019). The HUMAC360 (Computer Sports Medicine Inc.,

Stoughton, Massachusetts) is a linear position transducer which utilizes a retractable belt that can be connected to a barbell, to measure displacement. Prior researchers have assessed the reliability of the HUMAC360 to measure hand velocity during a punch (House and Cowan,

2015), however, no researchers have assessed the validity and reliability of the HUMAC360 to measure velocity during the free weight barbell BS and BP exists.

Specific Aims

1. To assess the validity of the HUMAC360 and its ability to measure mean and peak velocity

during the barbell BS and the BP, in comparison to the criterion.

a. We hypothesize that the HUMAC360 will be able to accurately measure both mean

and peak velocity in a valid manner.

2. To assess the reliability of the HUMAC360 and its ability to measure mean and peak velocity

during the barbell back squat and the bench press between trials.

4 a. We hypothesis that the HUMAC360 will be able to accurately reproduce mean and

peak velocity between trials in a reliable manner.

CHAPTER II

LITERATURE REVIEW

This investigation attempts to assess the validity and reliability of the HUMAC360 and its ability to measure velocity during the barbell BS and BP.

Velocity-Based Training

This section reviews the use and application of velocity-based training in previous literature.

(Dorrell et al., 2020) The purpose of this study was to assess the effect VBT has on maximal strength for the BS, BP, strict overhead press, and deadlift, as well as vertical jump height in comparison to PBT.

Sixteen resistance trained (≥2 years) men (mean±SD, 24±6 years; 89.3±13.3 kg;

180.2±6.4 cm; 1-RM: BS = 140.2±26.0 kg; BP = 107.7±18.2 kg; overhead press = 61.3±8.7 kg; deadlift = 176.6±27.2 kg) completed the study. Participants were randomly assigned into a VBT group and PBT group. At baseline and following a six-week resistance training program with two sessions per week, participants completed a 1-RM assessment for the BS, BP, overhead press, and deadlift, as well as a CMJ assessment using a Just Jump mat (Probiotics, Huntsville,

AL). The resistance training program was designed utilizing wave periodization with the number of sets (2-3), and rest times consistent between groups, while the relative loads, which ranged from body weight to 95% 1-RM, were based off of MCV (VBT group) or percentages of the predetermined 1-RM (PBT group). During the training program, each session consisted of the four previously mentioned compound movements (BS, BP, overhead press and deadlift) with

6 the addition of barbell squat jumps, seated row, and walking lunges in session 1 and barbell squat jumps, plyometric push-ups, and barbell hip thrusts in session 2. For the PBT group, the training program was completed as designed using the prescribed repetitions and intensity. For the VBT group, during the compound movements, MCV was monitored by a linear position transducer

(LPT) attached to the barbell (GymAware PowerTool Kinetic Performance Technology,

Mitchell, Australia). Velocity-based training was integrated into the base training program through the use of velocity zones and velocity stops, established from previous literature, to dictate changes in load and repetitions completed. Specific velocity zones were established for each movement and each relative load. A set was terminated if velocity fell beneath 20% of the specific target zone, which was followed by a decrease in load for the subsequent sets to achieve the desired velocity. Participants in the VBT group were also provided intra-set auditory feedback based on the MCV for each repetition.

A significant increase in strength was observed for BP following both training groups, however, the increase was significantly greater following VBT (8%), in comparison to PBT

(4%). Additionally, a significant increase (5%) in CMJ height was observed in the VBT group, with no change observed in the PBT group. Similar increases in strength were observed for BS

(VBT 9%, PBT 8%) and OHP (VPT 6%, PBT 6%), with no difference between groups.

Interestingly, a significant decrease in training volume for BS (-8.80%, p = 0.033), BP (-5.56%, p = 0.013), and overhead press (-5.86%, p = 0.049) was observed in the VBT group.

This study indicates that VBT programs in resistance-trained individuals may result in greater increases in maximal strength and power while also decreasing overall training volume.

Therefore, resistance-trained individuals may utilize VBT to obtain enhanced strength and power adaptations while limiting strain on the body. This decrease in training volume may ultimately

7 aid in preventing overtraining in athletes and reduce the potential of injuries, certainly for those athletes that are resistance training. Injury prevention in an athletic setting may play a large role in athlete productivity as well as career longevity.

(Gonzalez-Badillo et al., 2015) The purpose of this study was to analyze the effects

VBT, along with jumps and sprints, may have on strength, sprint speed, CMJ height, and maximal aerobic speed (MAS) in young soccer athletes during their competitive season.

A total of 44 young soccer athletes completed the study. Participants were categorized into 3 separate groups; under 16 (mean±SD, U16: n = 17; 14.9±0.3 years; 175.5±5.6 cm;

67.7±9.2 kg), under 18 (U18: n = 16; 17.8±0.4 years; 176.1±6.2 cm; 73.7±9.2 kg), and under 21

(U21: n = 11; 19.2±1.2 years; 178.1±6.7 cm; 75.5±4.4 kg). Prior to any testing, participants completed four preliminary familiarization sessions emphasizing sufficient squat and countermovement jump technique. Participants completed assessments before and after a 26- week period in which typical soccer training was continued for all groups, while the U16 and

U18 participants completed a VBT program and the U21 group did not complete any strength training. Testing was completed over two days and was at least 48 hours after the participants’ most recent game. Testing Day 1 consisted of two 20-m sprints (T20), CMJ, and a progressive isoinertial loading test for the full squat. Testing Day 2 consisted of a running test to determine

MAS.

The two 20-m sprints were assessed for time through the use of photocell timing gates

(Polifemo Radio Light; Microgate, Bolzano, Italy) placed at the start and end of the sprints. A rest time of three minutes separated each sprint. The best time between each effort was utilized for the analysis. The CMJ was utilized to assess vertical jump height by measuring flight time

8 using an infrared timing system (Optojump; Microgate). Participants were instructed to maintain a hand position on their hips through the entire movement, make a downward movement to a knee angle of 90°, and to jump with maximal effort while keeping their legs straight during the flight phase. The isoinertial test consisted of a BS with increasing loads completed on a Smith machine (Multipower Fitness Line, Peroga, Spain) until the participant obtained a load resulting in a velocity of ~1.00 m·s-1. During the squat, MPV was monitored using the T-Force system

(Ergotech, Murcia, Spain) with a sampling rate of 1,000 Hz. MPV is the mean velocity from the start of the concentric phase until the acceleration of the bar is less than the acceleration of gravity (-9.81 m·s-2). The eccentric phase was controlled at a velocity of 0.50-0.65m·s-1 while the concentric phase which was completed as fast as possible. A load of 30 kg was utilized for the initial load with the addition of 10 kg between each subsequent set thereafter. Participants completed three repetitions with each load and each set was separated by a 4-minute rest.

Testing was completed when participants completed a load that resulted in a MPV of ~1.00 m·s-1

(V1LOAD). This specified velocity was chosen as it correlates to ~56% 1-RM (Alverz-San

Emeterio et al., 2011) and was utilized as the maximal load during the VBT program for the squat exercise. The MAS running test was a modified version of the University of Montreal

Track Test (Kotzamanidis et al., 2005) and was conducted on a 400-m track with markers every

25-m. Participants began at a speed of 8.00 km·h-1 with a continuous increase of 1 km·h-1 every two minutes. MAS values were obtained when the participant failed on two consecutive efforts to complete the next marker in the allotted time.

During the 26-week VBT program, the U16 and U18 participants completed two training sessions each week. These training sessions consisted of squats and weighted countermovement jumps at loads relative to V1LOAD (40-105%), as well as box jumps, sled towing, hurdle jumps,

9 sprints, and change of direction sprints. In weeks seven and fifteen, V1LOAD was reassessed and loads utilized in the training program were altered accordingly. A weighted vest with loads of 5-10 kg was worn during the change of direction sprints. A load of 5-10 kg was utilized during the sled towing exercise. Each exercise consisted of two to five sets, separated by 3 minutes of rest.

Following the VBT program, a significant increase in CMJ height was observed for both the U16 (Cohen’s d = 0.91, p<0.001) and U18 (Cohen’s d = 0.90, p<0.001) groups, but not for the U21 group. A significant decrease in T20 time was observed for the U18 group (Cohen’s d

= 0.37, p = 0.02). A significant increase in V1LOAD was observed for the U16 (Cohen’s d =

2.86, p<0.001), U18 (Cohen’s d = 1.31, p<0.001), and U21 (Cohen’s d = 2.38, p<0.001) groups.

An increase in MAS was also seen in the U16 group (Cohen’s d = 0.52, p = 0.02). The U16 group showed significantly greater increases in V1LOAD in comparison to the U18 group

(Cohen’s d = 1.13, p<0.001) and U21 group (Cohen’s d = 1.49, p<0.001) with no significant difference the U18 and U21 groups.

From this study, it is clear that a VBT program completed during a competitive soccer season has the ability to increase CMJ height and load the elicits a velocity of ~1.00 m·s-1 in younger athletes. This study also indicates that VBT may be more beneficial to younger athletes with less resistance training experience and higher potential for strength increases.

(Shattock and Tee, 2020) The aim of this study was to assess the effect two autoregulation methods, VBT or perceived exertion (PE) using RPE and RIR scales, on CMJ height, maximal strength for the BS and BP, and sprint speed. Autoregulation is a structured

10 approach to alter training volume and/or load, in real time, with respect to variations in individual performance.

Twenty semi-professional, resistance-trained, rugby players (mean±SD, 22±3 years,

94.3±15.5 kg, ≥ 2 years’ experience) completed the study. Prior to completing the study, all participants completed one week of VBT familiarization, and were previously familiarized to category-ratio RPE and RIR. The study consisted of completion of two sequential 6-week training blocks, with Block 1 focusing on maximal strength and Block 2 focusing on strength- speed. For Block 1, participants were randomly separated into a VBT group (n = 10), in which

MCV was utilized for autoregulation, or a perception of effort (PE) group (n = 10), in which both

RPE and RIR scales were utilized for autoregulation. In Block 1, participants completed four session per week with three exercises completed each session. Eight sets of three repetitions were completed for each exercise with a corresponding load aimed to be greater than 85% 1-RM.

During each session, the respective autoregulation method was utilized between each set to adjust load to adhere to the desired load dictated by the training program. During Block 2, participants completed the training program utilizing the opposing autoregulation method.

During Block 2, participants completed three sessions per week with four exercises completed each session. Six sets of four repetitions were completed for each exercise with a corresponding load aimed to be between 70-80% 1-RM. The designated autoregulation method was utilized between each set in the same manner as Block 1.

For VBT, the researchers worked to establish upper body and lower body movement velocity ranges that correlated to specific relative loads. A PUSH accelerometer (PUSH band,

PUSH, Inc.) was worn on the right forearm of the participant, measuring velocity for each repetition at a sampling rate of 200 Hz. If the participant completed two repetitions in a set

11 above or below the desired velocity range, load was adjusted, respectively. For the PE group, following each set, participants dictated a rating for both the RPE and RIR scales. These scales were used to autoregulate load. If participants ratings were higher or lower than the desired ratings, load was adjusted for the subsequent sets, respectively.

Prior to Block 1, participants completed a CMJ, a 1-RM protocol for the BS and BP, and a 10, 20, and 40-meter sprint speed test. These performance tests were reassessed between Block

1 and Block 2, as well as following Block 2. The countermovement jump was tested using the

MyJump 2 (Version 1.0.11) smartphone application which utilizes the devices (iPad 4, iOs

10.3.3) camera to measure flight time. Participants completed three jumps in which they were instructed to keep their legs straight during the flight phase and maintain a hand position on their hips. The attempt with the greatest height was used for data analysis. The 1-RM protocols were completed as outline by the National Strength and Conditioning Association. Sprint speed was assessed using a single beam photocell timing system (Brower Timing Systems, IR Emit, Draper,

Utah).

Following each training block, a significant increase was observed in both VBT and PE for the CMJ (8.2±1.1%, 3.8±0.9%, respectively), BS 1-RM (7.5±1.5%, 3.5±0.8, respectively), and BP 1-RM (7.7±2.1%, 3.8±0.9, respectively). A significant difference between conditions was observed for CMJ (g = 1.78), BS 1-RM (g = 1.37), and BP 1-RM (g = 0.98) favoring VBT.

This study indicates that the use of VBT as an autoregulation method in training may result in larger increases in maximal strength and countermovement jump height in comparison to the more traditional perceived exertion scales.

(Orange et al., 2020) The purpose of this study was to compare the effects of VBT and

PBT on maximal strength in the BS, sprint time, CMJ and drop jump (DJ) height, and MV.

Twenty-seven academy rugby players volunteered for the study and were randomly separated into a VBT group (mean±SD, 17±1 years; 178±5.3 cm; 81.8±11.9 kg; 1-RM =

137±18.5 kg) and a PBT group (17±1 years; 181±6.3 cm; 84.9±11.9 kg; 1-RM = 136±16.6). At baseline and following a 7-week resistance training program with two sessions per week, participants completed multiple performance tests over three days separated by 24 to 48 hours.

Testing Day 1 consisted of a CMJ, DJ, and 30-meter sprint assessment (30MS), testing Day 2 consisted of a 1-RM protocol for the barbell BS, and testing Day 3 consisted of load-velocity relationship assessment.

Countermovement jump and drop jump height were both assessed by the Optojump photocell system (Optojump, Microgate) sampling at 1000 Hz. For each jump, participants were instructed to jump as high as possible, maintain their hands on their hips, and maintain straight legs during the flight phase. For the DJ, participants stepped off a 30-centimeter box with an individual leg of their choice, landed on two feet, and immediately jumped with an effort to minimize ground contact time. The 30MS was completed outdoors on artificial turf and assessed through the use of a photocell timing system (Witty Timing System; Microgate, Bolzano, Italy), measuring at 5-, 10-, 20-, and 30-meters. Relative loads for the 1-RM protocol were utilized based off of self-reported estimations made by the participant. The 1-RM protocol consisted of five repetitions at 50% 1-RM, three repetitions at 70% 1-RM, and two repetitions at 80% 1-RM, followed by up to five attempts at a 1-RM. This established 1-RM was utilized for the load- velocity relationship assessment. The assessment consisted of three repetitions at 40% 1-RM, three repetitions at 60% 1-RM, two repetitions at 80% 1-RM, and one repetition at 90% 1-RM.

During each repetition, participants were encouraged to complete each repetition as fast as possible and MCV was measured by a GymAware Powertool (Kinetic Performance

Technologies, Canberra, Australia). Individualized load-velocity relationships were established by plotting each MCV over relative loads and regression line.

Prior to each session, participants completed a perceived wellness questionnaire to assess muscle soreness, fatigue, stress, sleep, and mood using a 7-point Likert scale. Each session in the resistance training program consisted of four sets of five repetitions for the barbell BS followed by a Nordic lower or Romanian deadlift, an upper-body push movement, an upper- body pull movement, and a core exercise. RPE was obtained following each set utilizing the

OMNI Perceived Exertion Scale for Resistance Exercise. For Session 1, the BS was completed using a load of 80% 1-RM, whereas for Session 2, the BS was completed using a load of 60% 1-

RM. For the supplementary exercises following the BS, bodyweight or RIR was utilized to establish load. For the PBT group, load for the BS was not adjusted over the seven-week training program. For the VBT group, the GymAware Powertool was used to measured MCV and mean power (MP) for each repetition. A subjective target velocity was established for the specific loads of 60 and 80% 1-RM. The first set was completed with loads of 60 and 80% 1-

RM and thereafter, if the maximum MCV during the set increased above or fell below the target velocity by 0.06 m·s-1, the load for subsequent sets would be adjusted respectively by 5% 1-RM.

Mean concentric velocity and mean power during the training session were most likely greater for the VBT group in comparison to the PBT group. Perceived exertion was likely lower for the VBT compared to the PBT group. With regards to maximal strength, the PBT group resulted in likely to most likely improvements with the VBT group resulting in likely to very

14 likely improvements. Additionally, the VBT group showed likely to very likely improvements in

CMJ height and BS MCV at 40 and 60% 1-RM.

This study indicates that that utilizing MCV to adjust barbell BS load during VBT allows for similar increases in strength, when compared to traditional PBT. Additionally, VBT may result in improvements in CMJ height and MCV at relative loads of 40% and 60% 1-RM. This study also indicated that utilizing VBT may result in a decrease in PE.

Velocity-Based Training Summery

The foundation for utilization of velocity-based training is its ability to provide feedback on intensity in real time which can be used to autoregulate training. Feedback from VBT is objective and provides specific quantitative data allowing for more specific adjustments during training in comparison to perceived exertion scales which provide more subjective feedback.

Utilization of velocity ranges as a way to dictate repetitions completed has been shown to significantly decrease total training volume over a six-week training program, while enhancing strength and power gains in comparison to traditional percentage-based training (Dorell et al.,

2020). Velocity-based training has also been demonstrated to significantly improve various performance variables including countermovement jump, 20-m sprint time, and load eliciting a velocity of ~1.00 m·s-1 in young athletes (Gonzalez-Badillo et al., 2015). Additionally, VBT has been demonstrated to provide more clear improvements in CMJ height, in comparison to traditional PBT (Orange et al., 2020) and PE autoregulation (Shattock and Tee, 2020), while providing similar and or greater increases in maximal strength. Lastly, VBT as a means to autoregulate training load during individual sessions may provide more favorable increases in

15 maximal strength for the BS and BP, in comparison to traditional PE scales (Shattock and Tee,

2020).

Load-Velocity Relationship

The section reviews the relationship between submaximal loads and velocity assessed in previous literature.

(Gonzalez-Badillo & Sanchez-Medina, 2010) The purpose of this study was to assess the relationship between MPV and 1-RM for the BS.

One hundred and twenty resistance trained men (mean±SD, 24.3±5.2 years, 180±7 cm,

78.3±8.3 kg, 1-RM: 87.8±15.9 kg; ≥1.5 years’ experience) volunteered for the study and completed the first trial. A total of fifty-six participants returned for a second trial after 6-weeks of training. During each trial, participants completed a standardized warm up followed by a 1-

RM BP protocol completed on a Smith Machine (Multipower Fitness Line, Peroga, Spain) while

MPV was being monitored by a T-Force system (Ergotech; Murcia, Spain) at a sampling frequency of 1000 Hz. A pause of 1.5 seconds was utilized during the BP to minimize the effect of the stretch reflex. The 1-RM protocol began at 20 kg for all participants and was followed by increases of 10 kg until MPV was lower than 0.5 m·s-1. Subsequently, loads were increased with smaller increments of 1-5 kg until a 1-RM was achieved. A total of 3 repetitions were completed for lighter loads (MPV>1.0 m·s-1), two repetitions for medium loads (0.65m·s-1

1), and 1 repetition for heavy loads (MPV<0.65 m·s-1) with a rest time of 2-3 minutes for lighter and medium loads and 5-6 minutes for heavy loads. For the purpose of velocity assessment, the fastest MPV was utilized for the analysis. During the 6-week intermission, participants did not

16 undergo a specific training program, however, continued with their usual training routine (2-3 sessions/week), where they were encouraged to include the BP (3-5 sets, 4-12 repetitions, 60-

85% 1-RM). A second trial was utilized to assess any possible differences in velocity with increases in maximal strength.

Following the analysis, a strong correlation (R2 = 0.98) was observed between MPV and

%1-RM for the collective data obtained from both trials. Between trial one and trial two, an increase of 9.3 ± 6.7% was observed for the 1-RM, however, no significant differences were observed for the velocity values associated with relative loads between trials, providing a mean

ICC (1,k) for MPV of 0.87 (range: 0.81 - 0.91).

This study indicates that there is a strong correlation between MPV and %1-RM values for the BP completed on a Smith machine. Also, increases in maximal strength does not appear to effect MPV at specific %1-RM.

The influence of the measurement of velocity was also addressed as a potential difference with other studies, indicating that the method for obtaining mean velocity may affect the velocities associated with %1-RM. This study utilized MPV, to minimize the effect of the breaking phase in the BP. Using mean velocity of the entire concentric phase, instead of the propulsive phase, may result in variation of data, specifically at lighter loads where there is a more prominent breaking phase.

(Jidovtseff et al., 2011) The purpose of this study was to assess the load-velocity relationship and thereafter determine 1-RM equations utilizing a load-velocity profile.

One hundred and twelve (90 men, 22 women) participants (mean±SD, 23±4; 72±14 kg;

177±11 cm) from three collective studies (S1-S3) were utilized in this analysis. Procedures

17 across each study were consistent, however, differed in relative load. Testing was completed on two days separated by a week. Day 1 consisted of BP familiarization and a 1-RM protocol

(Kraemer and Fry, 1995) completed on a Smith machine (Multipower M433, Salter S.A.,

Barcelona, Spain). Only the concentric portion of the movement was completed with the starting position of the barbell being 3 cm above the participants chest. Day 2 consisted of each participant being assessed at 3 or 4 relative loads, differing only across each study (S1: 30, 50,70, and 90% 1-RM; S2: 40, 60, and 80% 1-RM; S3: 30, 50, 70, 95% 1-RM). Four individual efforts were completed for each load ranging from 30-40% 1-RM, three efforts for loads ranging from

50-70% 1-RM, and 2 efforts for loads from 80-95% 1-RM. MV was sampled at 1,000 Hz by a linear position transducer (Celesco Transducer Products, Inc., model PT5DC, Chatsworth,

California, USA) attached at the end of the barbell on the participants left hand side. The best effort achieved for each load was utilized for the statistical analysis where a regression line was then created for each participant’s load-velocity relationship. From the linear regression, slope was determined and theoretical MV at 0 kg (MV0) and theoretical load at 0 m/s-1 (LD0) were calculated.

Through the analysis, a strong correlation was observed between 1-RM and LD0 (r =

0.98) for the collective 3 studies. Correlations between 1-RM and LD0 did not differ between S1

(r = 0.96), S2 (r = 0.95), and S3 (r = 0.95).

This study indicates that a relationship between mean velocity and load exists and can be utilized to predict 1-RM by completing individual efforts at submaximal loads. Furthermore, utilization of submaximal loads of 40, 60, and 80% 1-RM (S2) provides a similar estimation of

LD0 when compared to completing submaximal loads of 30, 50, 70, and 90% 1-RM (S1) or 95%

1-RM (S3).

With no significant difference in estimated LD0 between studies, individuals have no need to surpass a relative load of 80% 1-RM to obtain a predicted 1-RM. This allows for individuals to obtain an accurate estimate without the completion of nearly maximal efforts.

(Loturco et al., 2017) The purpose of this study was to assess the load-velocity relationship for both the Smith machine and free-weight BP and establish velocity ranges for respective relative loads.

Thirty-six high level athletes participating in either rugby (mean±SD, Union: n = 18;

24.7±4.7 years 97.4±10.2 kg; 181.6±7.5 cm; Sevens: n = 8; 24.0±3.1 years; 88.8±6.4 kg;

181.2±6.8 cm) or a combat sport (mean±SD, n = 10; 23.8±2.4 years; 74.1±4.3 kg; 179±6.2 cm) completed the study. Testing was completed on two days separated by a week. Each day consisted of a controlled warm-up and a 1-RM protocol completed with either a Smith machine

(Hammer-Strength, Rosemont, IL, USA) or utilizing a free weight barbell in a randomized order.

Relative loads for the 1-RM protocol were established based off the participants estimated 1-RM of which they self-reported. Participants completed four repetitions at 40% 1-RM, three repetitions at 50% 1-RM, and two repetitions at 60% 1-RM, followed by five attempts at a 1-

RM. Three minutes of rest was allowed for participants between sets. During each set, MPV was monitored by a linear position transducer, T-Force (T-Force Dynamic Measurement System,

Ergotech; Murcia, Spain), which attaches to the bar via a velcro strap. The best MPV value for each relative load was utilized for the statistical analysis.

A strong correlation was observed between load (%1-RM) and MPV for both the Smith machine (R2 = 0.97) and the free-weight (R2 = 0.96) BP. No significant difference was observed

19 for MPV between the Smith machine and free-weight at relative loads, however the Smith machine did result in a heavier 1-RM.

This study indicates that a strong negative correlation exists between MPV and relative loads. Although individual’s maximal strength may differ between Smith machine and free- weight BP, MPV remains consistent for the respective relative loads.

(Pestana-Melero et al., 2018) The purpose of this study was to assess the reliability of the load-velocity relationship predicted by both a linear and polynomial regression mode as well as comparing variables of the concentric only and full motion BP.

A total of 30 sports science students (mean±SD, 21.2±3.8 years; 72.3±7.3 kg; 178±7 cm) with at least one year of resistance training experience completed the study. The study consisted of two familiarization visits and four testing trials separated by at least 48 hours. The testing trials consisted of a standardized warm up followed by an incremental loading assessment for the

BP completed on a Smith machine (Technogym, Barcelona, Spain) utilizing either a concentric only (CO) movement or an eccentric and concentric (EC) movement. Mean velocity was monitored during each press by a T-Force unit (T-Force Dynamic Measurement System,

Ergotech; Murcia, Spain) sampling at 1000 Hz. The movement (CO or EC) the participant completed for the first trial was randomized and completed in back-to-back trials. The incremental loading assessment began with one set of five repetitions with the unloaded bar.

This was followed by subsequent increases of 10 kg until the load elicited an MV of <0.50 m·s-1.

Thereafter, loads were increase by 1-5 kg until a 1-RM was obtained. A total of three repetitions were completed for loads eliciting an MV >1.0 m·s-1. Two repetitions were completed for loads with an MV range of 0.65 m·s-1 ≤ MV≤ 1.0 m·s-1. Lastly, one repetition was completed for loads

20 with an MV of < 0.65 m·s-1. Participants were instructed to complete the movement as fast as possible for each repetition and the best MV was utilized for the analysis. Mean velocities for each relative load (ranging from 20-100% 1-RM in increments of 5%) were obtained after applying linear and polynomial regressions to the data collected.

A strong relationship was observed between MV and %1-RM for CO utilizing a linear regression (R2 = 0.97-98, F = 6687.9-9113.8) and a polynomial regression (R2 = 0.97-0.98, F =

4098.5-5410.3). A strong relationship was also observed between MV and %1-RM for EC utilizing a linear regression (R2 = 0.97-0.98, F = 9308.0-9596.3) and a polynomial regression (R2

= 0.98, F = 5143.4-5324.4). High reliability was observed between trials for both CO (CV: linear = 4.39%; polynomial = 4.68%) and EC (CV: linear = 4.70%; polynomial = 5.04%). Post hoc comparisons revealed that the linear regression had higher reliability for all %1-RM except for 40% 1-RM, in which the polynomial regression was higher. No significant difference was observed for the reliability of the load-velocity relationship between CO and EC.

From this study it is clear that, regardless of utilizing a concentric-only movement or an eccentric-concentric movement, a load-velocity relationship exists and does not differ in reliability. This study also indicates that linear regressions give higher absolute reliability for the load-velocity relationship at moderate to high intensities, in comparison to polynomial regressions.

Load-Velocity Relationship Summery

When velocity is used to dictate intensity during training, it is necessary to establish a clear relationship between relative load and velocity. Various measures of velocity may be utilized to assess the relationship. MPV, defined as the mean velocity from the start of the

21 concentric phase until the acceleration of the bar is less than the acceleration of gravity (-9.81 m·s-2), has been shown to have a strong correlation to relative load in the BP without a significant difference between Smith machine and free-weight (Loturco et al., 2017).

Additionally, increases in maximal strength does not affect MPV at specific relative loads

(Gonzalez-Badillo & Sanchez-Medina, 2010).

MV, in comparison to MPV, has also been shown to be a reliable measurement when assessing the load-velocity relationship. When utilizing MV of submaximal loads to predict

LD0, a strong correlation is seen between 1-RM and LD0. Furthermore, using relative loads of

40, 60, and 80% 1-RM provides similar estimations of LD0 when compared to completing loads of 30, 50, 70, and 90% 1-RM or 95% 1-RM, proposing it unnecessary to exceed 80% 1-RM to acquire accurate 1-RM predictions (Jidovtseff et al., 2011). Linear and polynomial regression have both been shown to provide a strong relationship between MV and %1-RM during a CO and an EC BP, however, a linear regression may provide higher reliability at moderate to high intensities (Pestana-Melero et al., 2018).

In summation, a load-velocity relationship exists and MPV and or MV can be utilized to assess this relationship. Furthermore, relative loads between 30 and 80% 1-RM may be completed to predict LD0 and ultimately 1-RM, without completing heavier loads equal to or exceeding 90% 1-RM.

Velocity Assessment Tools

This section reviews previous literature assessing the validity and reliability of tool used to measure movement velocity.

(Appleby et al., 2018) This study aimed to determine the validity and reliability of two barbell displacement methods in comparison to a criterion marker during heavy barbell BS.

Twelve college and professional rugby union players (mean±SD, 24.5±3.2 years;

102.7±10.4 kg; 184.8±5.1 cm; 1-RM:196.3±29.2 kg) volunteered for the study. Testing was completed on two days with an average of six days separating Day 1 and Day 2. During Day 1, participants completed a series of warm-up sets at submaximal loads followed by 1-RM protocol.

Day 2 consisted of a standardized warm up of 10 minutes of cycling, 10 minutes of self-directed mobility work, a set of 6 reps at 50% 1-RM, and a set of 4 at 60% 1-RM. Participants then completed the displacement assessment in which consisted of 2 sets of 2 reps at 70, 80, and 90%

1-RM (for a total of six sets). During the assessment, the criterion measure was assessed via 10- camera digital optical system (Vicon MX; Vicon, Oxford, United Kingdom), with motion captured at three different locations: the seventh cervical vertebra (C7) and one marker placed at the end of the barbell on both the left (LHS) and right (RHS) side of the barbell. A LPT was placed in the left grip section of the barbell, 65 cm away from the center of the barbell. The LPT as well as LHS and RHS were analyzed for validity in comparison to the criterion marker at C7.

Reliability, using coefficient of variance (CV%), and ICC, was also assessed for all four measurements and presented relative to barbell load.

Moderate reliability was obtained for almost all measures of the barbell and are expressed as an average for all loads (LPT: CV% = 6.6%, ICC = 0.67; LHS/RHS: CV% = 5.9-7.2%, ICC =

0.55-0.67; C7: CV% = 6.6%, ICC = 0.62). In reference to validity, LPT bias ranged from 0.9-

1.5% (r = 0.96-0.98) and barbell ends bias ranged from 4.9-11.2% (r = 0.71-0.97).

This investigation indicates that mean barbell displacement increased as the reference of measurement moved away from the individual’s midline and the LPT was the most valid

23 measurement in comparison to the criterion measure. The researchers indicate that the utilization of the LPT in this specific placement will provide more consistent displacement data as well as data that has higher correlations to the criterion marker.

The influence of total exercise load was also addressed, indicating possible errors associated with the method of determining load. Barbell loads were analyzed as absolute weight instead of percentages of 1-RM, which does not allow for displacement values specific to relative loads. Displacement assessed through percentages of 1-RM may provide smaller variations in data.

(Lorenzetti et al., 2017) The purpose of this study was to assess the validity and reliability of average and maximal velocity measurements from three LPTs and one accelerometer-based system during traditional and ballistic squats.

Nine strength trained men (mean±SD, 30.9±5.9 years; 92.0±8.7 kg; 182±6 cm; 1-RM:

171±20 kg) volunteered for this study, with testing conducted over one day. Participants completed a 5-minute warm-up, followed by 2 sets of 5 repetitions with a load equal to 70% 1-

RM for traditional squats and two sets of five repetitions with a load of 25 kg for ballistic squats, in a randomized order. Specification of how the 1-RM was obtained was not clarified. During each squat, the barbell was configured with a T-Force unit (T-Force Dynamic Measurement

System, Ergotech; Murcia, Spain) connected furthest from center in the grip section of the barbell on the left, a Tendo unit (TENDO Sports Machines; Trencin, Slovak Republic) connected furthest from center in the grip section of the barbell on the right, and a GymAware unit (version

1.1.2, Kinetic Performance Technology, Mitchell, Australia) positioned at the outer portion of the barbell on the right. The barbell was also outfitted with a Myotest unit (Myotest SA, Sion,

Switzerland) connected directly to the grip section of the barbell just inside the T-Force positioning during the ballistic squat. Each squat was also assessed by a 16-camera digital optical system (Vicon MX; Vicon, Oxford, United Kingdom) at a sampling frequency of 100 Hz, used as the criterion measure. MV and PV were calculated using Excel (version 14.5.2,

Microsoft, USA).

A significant correlation was observed for the T force (r = 0.97,0.93), Tendo (r =

0.96,0.93) and GymAware (r = 0.95, 0.95) in comparison to the criterion measure for MV and

PV, respectively. RMSE was higher for PV (T-Force: RMSE = 0.15; Tendo: RMSE = 0.19;

GymAware: RMSE = 0.16) in comparison to MV (T-Force: RMSE = 0.07; Tendo: RMSE =

0.04; GymAware: RMSE = 0.06).

This study indicates that the T-Force, Tendo, and GymAware units are reliable tools and can accurately assess MV and PV at a load of 70% 1-RM. This study also indicates that these tools may have a higher range of error when assessing PV.

A relative load of 70% 1-RM was utilized to accommodate for any strength differences between subjects. This allowed for more consistent velocity data, however, utilizing only one relative load limits the analysis of each velocity tool. Including multiple relative loads may allow for the identification of limitations for each tool.

(Stock et al., 2011) The aim of this study was to assess the test-retest reliability of the

Tendo Weightlifting Analyzer (TENDO Sports Machines; Trencin, Slovak Republic) for PV during the free-weight BP.

Twenty-one resistance trained, young adult, men (mean±SD, 23.5±2.7 years; 90.5±14.6 kg; 1-RM: 125.4±184 kg) volunteered for the study. Testing was completed over 3 days with

25 each day being separated by at least 48 hours. Day 1 consisted of testing familiarization as well as a 1-RM protocol for the free-weight BP. Days 2 and 3 consisted of a brief warm-up followed by 9 single repetitions with loads ranging from 10-90% 1-RM with each set increasing by 10% in an ascending order and separated by 3 minutes. During the BP protocol assessment, PV was monitored by the Tendo Weightlifting Analyzer (Tendo). The Tendo sensor was situated on the floor directly below the barbells position during the press and the Velcro strap was attached to the outside of the barbell.

Test-retest data analysis revealed moderate to high reliability, with ICC2,1 values (10% =

0.72; 20% = 0.57; 30% = 0.81; 40% = 0.67; 50% = 0.79; 60% = 0.79; 70% = 0.81; 80% = 0.71;

90% = 0.56) for barbell velocity between Day 2 and Day 3 submaximal bouts. Standard error of measurement (SEM) was lowest at 30% 1-RM (0.06 m·s-1; 3.1% of mean velocity) and highest at

90% 1-RM (0.06 m·s-1; 12.6% of mean velocity). This study indicates that Tendo is a reliable tool for the assessment of velocity during the free weight BP at submaximal loads. Furthermore, this study indicates that the Tendo is most reliable at a submaximal load of 30% 1-RM and least reliable at a submaximal load of 90% 1-RM.

Utilizing free weight movements during the assessment of PV allows for greater applicability, however, this increases the chance of error due to horizontal displacement.

Therefore, a LPT may not be able to assess velocity as accurately as motion capture technology or laser optics.

(Perez-Castillo et al., 2019) The purpose of this study was to assess the validity and reliability of seven commercially available velocity transducers during multiple loads during the

BP.

Fourteen recreationally active, young adult, men (mean±SD, 22.9±1.6 yrs, 176±6 cm,

76.9±7.8 kg, 1-RM: 86.1±11.9 kg) completed the study. The study was conducted over two days with at least 48 hours separating each day. Day 1 consisted of a standardized warm-up consisting of jogging, self-selected dynamic stretching and mobility, and one set of five repetitions of a BP performed with an unloaded bar on a Smith machine. This was followed by a

1-RM protocol in which 1 to 10 kg were added after each set until a 1-RM was reached. A rest time of 4 minutes was taken between sets. Day 2 consisted of the same warm-up followed by the

CO BP at 5 relative loads (45, 55, 65, 75, 85% 1-RM) completed in an ascending order. A total of 3 repetitions were completed for each load with 15 seconds of rest between each repetition, in which the bar rested on safety stops, and 4 minutes of rest between each load. Side spotters were used to lower the bar after each repetition to eliminate the eccentric portion of the BP. During each BP protocol, the Smith machine was configured with eight devices for the measurement of velocity: Trio-OptiTrack, (criterion measure; V120:Trio; OptiTrack, NaturalPoint, Inc.), T-Force

(T-Force system, Ergotech; Murcia, Spain), Chronojump (Chronojump Boscosystem; Barcelona,

Spain), Speed4Lift (Speed4Lift; Mostoles, Madrid), Velowin (Velowin; DeporTeC), PowerLift,

PUSH band (PUSH band, PUSH, Inc.), and Beast sensor (Beast sensor, Beast Technologies Srl.;

Brescia, Italy).

The Trio-OptiTrack is an optical motion sensing system using three infrared cameras fixed onto a rectangular frame that analyzes 3D position data via a reflective marker at a sampling rate of 120 Hz. The T-Force, Chronojump, and Speed4Lift are linear position transducers utilizing a cable-extension of which attaches to the barbell by way of a velcro strap.

Each of the three were set to a sampling rate of 1,000 Hz. The Velowin is an optoelectronic system using an individual infrared camera to analyze displacement of a reflector placed directly

27 on the barbell. PowerLift is a smartphone application that utilizes assessment of slow-motion video imaging at 240 frames per second. Video was taken by a researcher from in front of the participant at a distance of “approximately 1.5 m”. The PUSH Band and Beast Sensor are wearable wireless inertial measurement units which utilize a three-axis accelerometer and a gyroscope to assess orientation. The PUSH Band was worn on the participants dominant forearm, whereas the Beast Sensor was attached to the barbell via a magnet.

Table 1

Reliability Ranges of Mean Velocity Values for all Relative Loads

DEVICES

ICS SA LPT IMU Trio- T- PUSH Beast Optitrack Velowin Powerlift Speed4Lift Force Chronojump Band Sensor CV (%)

45% 1- 3.47 2.89 2.85 2.61 2.48 2.31 5.02 33.4 RM

55% 1- 2.22 3.27 3.97 2.39 1.82 2.09 7.84 24.2 RM

65% 1- 4.04 3.99 4.91 2.42 4.35 6.24 9.34 35 RM

75% 1- 4.15 6.01 3.69 3.92 4.78 4.53 14.6 40.2 RM

85% 1- 4.64 7.64 4.97 3.41 4.9 5.65 19.1 54.9 RM

ICC (3,1)

45% 1- 0.73 0.83 0.84 0.87 0.90 0.87 0.69 0.29 RM

55% 1- 0.93 0.79 0.85 0.84 0.95 0.90 0.46 0.64 RM

65% 1- 0.84 0.83 0.74 0.93 0.78 0.72 0.78 0.30 RM

75% 1- 0.83 0.68 0.87 0.81 0.77 0.85 0.50 0.31 RM

85% 1- 0.88 0.69 0.85 0.94 0.87 0.86 0.47 0.27 RM

ICS = Infrared Camera System; SA = Smartphone Application; LPT = Linear Position Transducer; IMU = Inertial Measurement Unit

This study indicates that linear velocity and position transducers, such as the T-Force, result in more reliable and valid velocity data in comparison to IMU devices. This research also indicates that the validity and reliability fluctuate with different relative loads, suggesting the use of relative loads instead of absolute loads when analyzing data. Utilization of absolute loads may result in loads that hold different relative value between participants, increasing variation of the data, leading to inconsistent and non-specific velocity ranges for loads.

(Garnacho-Castano, Lopez-Lastro, & Mate-Munoz, 2015) The purpose of this study was to assess the reliability and validity of the Tendo and its ability to measure velocity and power.

Seventy-one recreationally active, young adult, men (21.6±2.1 years; 71.9±10.7 kg;

176±8 cm) participated in the validity portion of the study whereas 32 returned for the reliability portion. Testing was completed on two days, separated by 1 week, where participants completed a back-squat protocol followed by a BP protocol on both days. Testing procedures were consistent between days. Participants completed a warm-up consisting of five minutes of jogging, five minutes of upper and lower extremity stretching, and mobility work. This was followed by eight repetitions of the bar, six repetitions with a 20 kg load, and four repetitions with a 30 kg load. A rest period of 1 minute was provided between each warm-up set and 3 minutes between the final warm-up set and the BS protocol. The BS and BP protocol were completed on a Smith machine (Multipower, Reebok) and consisted of 1 set of 4 repetitions with a 40 kg load, 1 set of 3 repetitions with a 50 kg load, 1 set of 2 repetitions with a 60 kg load, and

1 set of as many reps as possible with a load of 85% of their predicted 1-RM based of the velocity acquired from the T-Force Dynamic Measurement System (T-Force) (T-Force Dynamic

Measurement System, Ergotech; Murcia, Spain) and a prediction equation established in previous literature (Sanchez-Medina et al., 2010). A rest time of 5 minutes was taken between the BS protocol and the BP protocol. The Tendo and T-Force were used to monitor velocity and were positioned on opposite sides on the most distal position of grip portion of the bar. Validity was assessed for the Tendo through a comparison to the T-Force, where reliability was assessed by the comparison of day 1 and day 2 velocity and power data obtained from the Tendo.

High reliability was observed for Tendo from Day 1 to Day 2, with ICC values for both

MV and PV for the BS of 0.982, 0.966, respectively and for the BP of 0.977, 0.988, respectively. Tendo was also determined to be a valid measure, with ICC values for both MV and PV for the BS of 0.99 ,0.96, respectively, and for the BP of 0.99, 0.98, respectively.

This study indicates Tendo is a valid and reliable method to assess MV and PV. Also, for the purpose of assessing a linear transducer, the BS and BP completed on a Smith machine are sufficient movements to obtain consistent velocity data.

A Smith machine was used to address the influence of horizontal displacement on velocity data while squatting and during the BP. However, this may decrease applicability being that individuals may not have consistent access to a Smith machine.

Velocity Assessment Tools Summery

When assessing velocity or using velocity-based training, it is important to utilize velocity assessment tools that are valid and reliable. Linear position transducers, such as the T-

Force, Tendo, and GymAware, have been shown to have significant correlations to a criterion when measuring both mean velocity and peak velocity for the barbell BS (Lorenzetti, Lamparter, and Lüthy, 2017) at a relative load of 70% 1-RM. Tendo reliability is further supported, as it has

31 been shown to have high day to day reliability for the BS and BP when measuring MV and PV

(Garnacho-Castano, Lopez-Lastro, & Mate-Munoz, 2015). Additionally, Tendo has been observed to have moderate reliability at relative loads of 10, 20, 40, 80 and 90% 1-RM, as well as high reliability at relative loads of 30, 50, 60, and 70% 1-RM for the barbell BP (Stock et al.,

2011). Linear position transducers have also been established as more reliable that inertial measurement units (Perez-Castillo et al., 2019).

Utilization of absolute loads for analysis has been shown to result in moderate reliability

(Appleby et al., 2018), whereas utilization of relative loads has been shown to increase reliability

(Stock et al., 2011), suggesting the use of relative loading for assessment and analysis. Being that relative loads of 30, 50, 60, and 70% 1-RM produce the highest reliability for the Tendo unit, relative loads below or exceeding this range may be excluded or utilized warily.

CHAPTER III

METHODS

The following chapter provides the methods utilized to complete testing throughout the investigation.

Experimental Approach

Participants will be asked to report to the Exercise Performance and Recovery Lab on three separate occasions, with at least 48 hours separating each visit. Prior to Visit 1 through a remote consultation, participants will be informed of the risks and benefits of the study as well as complete a medical questionnaire, to assess eligibility, and an informed consent form. During

Visit 1, anthropometrics will be obtained followed by a 1-RM assessment for both the barbell BS and BP. During Visit 2 and Visit 3, participants will be asked to complete two sets of three repetitions for relative loads of 30, 50, 60 and 70% of their previously determined 1-RM, for the purpose of assessing velocity.

Figure 1

Study 1 Design

Participants will complete three visits, each separated by at least 48 hours. On Visit 1, participants provide a written informed consent, followed by a medical questionnaire, anthropometrics, and a one-repetition maximum (1-RM) assessment. During Visits 2 and 3, participants complete a velocity assessment for the BS and BP.

Participants

A total of 20 men and women with prior resistance training experience (≥ six months) will be recruited to participate in this study. Participants will not be required to be actively involved in resistance training immediately preceding the study. Inclusion criteria will require participants to be between the ages of 18 and 35 as well as be able to complete both the BS and

BP using a free weight barbell. Participants will be generally healthy and free from any cardiovascular, metabolic and or pulmonary diseases or injuries, as determined from a medical questionnaire. Additionally, participants with any musculoskeletal diseases or injuries, as well as being less than six months removed from any surgery of the upper or lower extremities, will be excluded from the research study. Participants will abstain from any physical activity for at least 48 hours prior to each visit as well as caffeine for at least 3 hours prior to each visit.

Procedures

The following section discusses all procedures to be utilized throughout the investigations.

1-Repetition Maximum Assessment

The 1-RM assessments during Visit 2 will be completed following the guidelines established by the National Strength and Conditioning Association (Haff & Triplett, 2015). The same Certified Strength and Conditioning Specialist (CSCS) will oversee all 1-RM protocols to monitor proper form and consistent progression. Assessment of the barbell BS 1-RM will be superset with the BP 1-RM assessment, following the same outlined guidelines. Participants will complete a standardized warm-up consisting of five minutes at a self-selected intensity on an

Airdyne bike (Schwinn, Pacific Cycle, Inc. Vancouver, WA), followed by 10 bodyweight squats, 10 walking bodyweight lunges, and 10 bodyweight push-ups. If a participant does not possess enough strength to complete normal push-ups, they may be done while resting on their knees, or against a wall. Participants will then complete three warm-up sets for both the BS and

BP, with each superset separated by one minute of rest. Each set will consist of up to 10 repetitions at 50% of their estimated 1-RM (set 1), up to five repetitions at 65% of their estimated 1-RM (set 2), and two to three repetitions at their estimated 80% 1-RM (set 3). This will be followed by up to five attempts at a 1-RM for both movements, with 2-3 minutes rest separating each squat and BP attempt allotting 4-6 minutes rest between 1-RM attempts for each exercise. Proper form for the BS will dictate participants must reach a position in which the top of their thigh is at least parallel to the ground prior to the ascent phase. Proper form for the BP will dictate participants must reach a point of contact between their chest and the barbell prior to the ascent phase, as well as maintain five points of contact (both hands, both feet, and glutes) throughout the movement. The greatest load completed with proper form will be considered the participants 1-RM.

Velocity Assessment

Upon arrival into the lab for Visits 2 and 3, participants will complete the same standardized warm-up outlined previously, excluding the push-ups which will be completed at a later time. This will be followed by two assessment protocols in which velocity during submaximal efforts will be measured for both the BS and BP, with the squat protocol being completed first. Following the squat protocol, the participant will have up to five minutes of rest as well as complete the warm-up set of push-ups prior to the bench protocol. Each assessment

36 protocol will consist of two sets of three repetitions at 30, 50, 60 and 70% 1-RM, with 2-3 minutes rest separating each set. During the BS, participants will be instructed to complete the eccentric phase in a controlled manor until the top of their thigh is perpendicular to the floor and complete a temporary pause before ascending. During the BP, participants will be instructed to lower the barbell until the bar is within 3cm of the sternum and complete a temporary pause before ascending. Participants will then be verbally encouraged to complete the concentric portion of the movement as explosively as possible while maintaining contact with the barbell and floor during the BS and the five points of contact, described previously, during the BP.

Velocity will be measured during each repetition by the criterion, Tendo (TENDO Sports

Machines; Trencin, Slovak Republic) and the HUMAC360 linear position transducer (Computer

Sports Medicine Inc., Stoughton, Massachusetts).

The Tendo will be placed on the floor and attached directly to the barbell by a velcro strap at the furthest left portion of the grip section of the barbell. Similarly, the HUMAC360 will be placed on the floor and attached directly to the barbell by a fabric strap at the furthest right portion of the grip section of the barbell. Both assessment tools will be fixed positionally in which the retractable belts are perpendicular to the ground and in line with the path of movement during each exercise. Velocity data for the Tendo is variable and dependent on speed of movement, however, should collect at a sampling rate between 100-200 Hz. Velocity data for the HUMAC360 will be collected at a sampling rate of 100 Hz.

The Tendo will provide both peak (PV) and mean concentric velocity (MCV) for each repetition. Velocity data from the HUMAC360 will be input into Excel (16.0.13231.20372,

Microsoft, USA) to calculate both PV and MCV of each repetition.

Statistical Analysis

Validity of the HUMAC 360 will be assessed through the use of dependent t-tests.

Specifically, data from the Tendo unit and HUMAC360 devices on Day 2 will be assessed for differences between devices at each specific relative load. Additionally, relationships between these variables will be assessed by Pearson product-moment correlation. Considerations of correlation strength will be as follows: trivial (<0.1), small (0.1-0.3), moderate (0.3-0.5), high

(0.5-0.7), very high (0.7-0.9), or practically perfect (>0.9) (Hopkins et al., 2009).

Reliability of the HUMAC360 will be assessed through the use of dependent t-tests, as well. Specifically, data from the HUMAC360 from Day 2 and Day 3 will be assessed for difference between trial days at each specific relative load. Additionally, test-retest reliability will be assessed using ICC’s 3,1. An alpha level of 0.05 will be utilized to determine statistical significance. All data will be analyzed using IBM SPSS Statistics for Windows (version 24;

IBM Corp., Armonk, NY, USA).

CHAPTER IV

FUTURE STUDY BACKGROUND

The following chapter provides the rationale and specific aims for a future investigation.

Rationale

Resistance training is commonly used to elicit hypertrophy, and improvements in maximal strength, and muscular power. Traditionally, load is dictated as a percentage of a 1-

RM, often referred to as PBT. This training technique is utilized due to the relationship between specific submaximal percentages of a 1-RM and the total number of repetitions completed before failure (Mayhew et al., 1992). Although this training technique has been shown to improve strength and hypertrophy (Baker, Wilson, and Carlyon, 1994), PBT does not utilize autoregulation, which is defined as the ability to increase or decrease load, with respect to individual performance within a specific training session (Mann et al., 2010). Autoregulation may be necessary given that maximal strength and training readiness can vary between training sessions due to several influences, including improper nutrition (Leveritt & Abernethy, 1999), lack of sleep (Reilly & Piercy, 1994), and other life stressors (Mann et al., 2016). This likely requires alteration of training load beyond the pre-prescribed intensity, suggesting the use of autoregulation may be advantageous while training. Traditional autoregulation methods include

RPE and RIR; however, concerns exist over the subjective nature of these measurements, potentially as a result of various definitions and understandings of perceived exertion and the scales (Borg, 1998, Borg & Noble 1974, Pageaux, 2016). Over the last decade, an increased popularity in VBT amongst strength and conditioning facilities and investigations has presented

39 itself (Gonzalez-Badillo and Sanchez-Medina, 2010, Jidovtseff et al., 2011, Pestana-Melero et al., 2018, Dorrell et al., 2020, Shattock & Tee, 2020, Orange et al., 2020,).

Velocity-based training is an autoregulation technique that uses movement velocity to identify exercise intensity. Multiple velocity variables, such as MCV (Pestana-Melero et al.,

2018) and MPV (Gonzalez-Badillo & Sanchez-Medina, 2010, Loturco et al., 2017), have been demonstrated to have a strong relationship (r2 ≥ 0.96) with %1-RM. This provides an inverse linear relationship, dictated as a load-velocity profile. As a result, using movement velocity allows for an accurate estimation of %1-RM and maximal strength (Jidovtseff et al., 2011), allowing for the detection of fluctuations in maximal strength within and between training sessions. Gonzales-Badillo and Sanchez-Medina (2010) also observed MPV at a specific %1-

RM, was not altered by significant increases in maximal strength, indicating each %1-RM has a specific movement velocity range. Ultimately, if movement velocity during an individual set varies significantly beyond an established velocity range, load can be adjusted for subsequent sets to assure the exercise is completed at the desired intensity. Researchers have demonstrated that using VBT over a 6-week training program may result in greater increases in maximal strength and power, while also decreasing total training volume in comparison to traditional PBT

(Dorrell et al., 2020). Furthermore, Shattock and Tee (2020) observed VBT to elicit larger improvements in countermovement jump height and maximal strength for the BS and BP, in comparison to using RPE and RIR.

While velocity at a specific %1-RMs does not appear to change with changes in maximal strength in resistance-trained individuals, it is uncertain how training status and/or sport participation may affect load-velocity profiles. The velocities at specific %1-RMs appears to be exercise specific, which allows for establishing %1-RM estimations or specific load-velocity

40 profiles (Jidovtseff et al., 2011). When comparing load-velocity profiles between men and women, however, differences in velocities at specific %1-RM and load-velocity slopes were observed for exercises such as the BS (Askow et al., 2019), BP (Torrejon et al., 2018), and military press (Fernandez et al., 2017). Furthermore, most previous work has only investigated recreationally active, or resistance-trained individuals (Gonzalez-Badillo and Sanchez-Medina,

2010, Loturco et al., 2017, Pestana-Melero et al., 2018) with no investigation assessing differences in velocity profiles between trained and untrained individuals. Given that neural adaptations, rather than hypertrophy, are primarily responsible for initial improvements in strength (Moritani, 1979), velocity at submaximal loads may potentially differ in trained individuals, as a result of improved motor unit activation and firing rate (Folland & Williams,

2007).

In a previous investigation, Cormie and colleagues (2009) observed that 12 weeks of power specific training significantly increased peak velocity (PV) during a countermovement jump in individuals with no previous resistance training experience. Additionally, Division I football players and track sprinters were observed to have greater PV during a countermovement jump in comparison to non-athletes (Cormie et al., 2009) indicating resistance training and sport participation may provide beneficial improvements for movement velocity. Moreover, Degens and colleagues (2019) observed that velocity at take-off during a CMJ was significantly higher for “power” and “team” athletes in comparison to non-athletes and “endurance” athletes. While these investigations failed to assess velocity using submaximal loads, they do demonstrate a potential difference in the load-velocity profiles between trained and untrained individuals, as well as athletes in comparison to non-athletes.

Collectively, these findings demonstrate that a relationship between load and velocity exists (Pestana-Melero et al., 2018, Gonzalez-Badillo & Sanchez-Medina, 2010, Loturco et al.,

2017) and may be a viable autoregulation technique during training, while also offering a potential for maximal strength estimation. Unfortunately, however, these data also demonstrate load-velocity profiles may differ between individuals, most notably between sex, training status and sport. To date, only three (Askow et al., 2019, Torrejon et al., 2018, Fernandez et al., 2017) investigations have assessed the effects of sex on load-velocity profiles, while no investigation, to our knowledge, has assessed the effects of training status and/or sport participation on load- velocity profiles during dynamic resistance exercise. Given that most strength and conditioning professionals work with multiple athletes with varied resistance training backgrounds and sport demands, further development of load-velocity profiles for specific training ages, sport types and sex is warranted.

Specific Aims

Velocity-based training as an autoregulation technique and estimation tool for maximal strength has increased in popularity among strength and conditioning facilities and research investigations (Gonzalez-Badillo and Sanchez-Medina, 2010, Jidovtseff et al., 2011, Pestana-

Melero et al., 2018, Dorrell, Smith, and Gee, 2020, Shattock and Tee, 2020, Orange et al.,

2020,). With the wide application of VBT, a greater understanding of the potential differences in load-velocity profiles between training age, sex, and athletic experience is necessary.

Researchers have demonstrated a strong relationship between relative training loads and mean velocity (MV) (Pestana-Melero et al., 2018), MPV (Gonzalez-Badillo & Sanchez-Medina, 2010,

Loturco et al., 2017), and MCV (Pestana-Melero et al., 2018). Additionally, this load-velocity

42 relationship appears to be exercise dependent (Conceição et al., 2016), yet unaltered by improvements in maximal strength (Gonzalez-Badillo and Sanchez-Medina, 2010). To date, only Torrejon et al. (2018), Balsalobre-Fernandez et al. (2017), and Askow et al. (2019) have examined velocity profiles between men and women, demonstrating that men produce higher velocities for relative loads and steeper load-velocity profiles. Moreover, researchers have only investigated recreationally active or resistance-trained individuals (Gonzalez-Badillo and

Sanchez-Medina, 2010, Loturco et al., 2017, Pestana-Melero et al., 2018) and no investigation has assessed trained vs. untrained individuals. Being that initial strength improvements are predominantly caused by neuromuscular adaptations (Moritani, 1979), load-velocity profiles may potentially differ as a result of increased motor unit recruitment in trained individuals.

Furthermore, during a vertical jump, athletes seem to have earlier EMG activity of greater amplitude than their non-athlete counterparts, (Viitasalo et al., 1998), indicating faster recruitment of more motor units’, greater neuromuscular adaptations, and better preparation of movement in athletes. With the large variability of load-velocity profiles reported for the BP between studies (Stock et al., 2011, Jidovtseff et al., 2011, Perez-Castillo et al. 2019), potentially as a result of differences in training and sex, further investigation of independent variables that may affect velocity profiles is warranted. Therefore, the purpose of this investigation is to assess potential differences in load-velocity profiles between training age, sex, and athletic experience. Specifically, we aim to:

1. Assess the velocity profiles of untrained individuals, non-athlete recreationally trained individuals, and experienced athletes for the barbell BS and BP.

a. We hypothesize that athletes will demonstrate higher velocities at submaximal loads in

comparison to the non-athlete recreationally trained individuals.

b. We hypothesize that non-athlete recreationally trained individuals will have higher

velocities at submaximal loads in comparison to the untrained individuals.

2. Compare velocity profiles, between men and women for the barbell BS and BP exercises.

a. We hypothesize that men will demonstrate higher velocities at submaximal loads in

comparison to women, however, the magnitude of difference will decrease as load

increases.

CHAPTER V

FUTURE STUDY METHODS

The following chapter provides the methods utilized to complete testing throughout the future investigation.

Participants

Up to 25 men or women for each group will be recruited to participate in this investigation, resulting in a total of 150 participants. Participants will have different levels of training and experience with resistance exercise, but will all be between the ages of 18 and 25.

Inexperienced participants will have no former exposure to resistance training of any kind. Non- athlete recreationally-trained individuals will have at least six months (≥ 3 days per week) of resistance training experience. Athletes will have at least six months (≥ 3 days per week) of resistance training and be on an active roster, or no more than 3 months removed from competition. Participants will be recruited from the University as well as local health and fitness facilities. Participants will complete a medical history questionnaire, provide written informed consent, be generally healthy and free from any cardiovascular, metabolic and/or pulmonary diseases or injuries. Additionally, participants with any musculoskeletal diseases or injuries, as well as being less than six months removed from any surgery of the upper or lower extremities, will be excluded from the research study.

Sample Size Estimates

A priori estimates of sample size were conducted on data from previous studies comparing movement velocity at multiple submaximal loads as well as load-velocity profiles between men and women (Askow et al., 2019, Fernandes, Lamb, and Twist, 2018, Fernandez,

Garcia-Ramis, Jimenez-Reyes, 2017). Data from these investigations indicated the estimated effect sizes (f) ranged from 0.53-0.55, 0.32-0.37, 0.56 and 1.08, for peak velocity, mean propulsive velocity, mean velocity, and slope, respectively.

The estimated total number of participants was calculated using a power analysis

(G*Power) as previously described by Beck (2013). Given the moderate effects reported by

Fernandez, Garcia-Ramis, and Jimenez-Reyes (2017) for mean propulsive velocity at 75% 1-

RM, an estimated effect size (f) of 0.32 was used. Specifications for the G*Power analysis were as followed: α = 0.05, power (1-ß) = 0.8; statistical test: Fixed effects analysis of variance

(ANOVA) with main effects and interactions. This analysis provided an estimated sample size of 134 participants. Therefore, we will recruit up to 150 participants, or 25 participants per group, to account for the failure of participants to complete the entire investigation.

Experimental Approach

Participants will be asked to report to the Exercise Performance and Recovery Lab on three separate occasions, with at least 48 hours separating each visit (Figure 1). During Visit 1

(V1) participants will be informed of the risks and benefits associated with the investigation, allowing for their informed written consent. Following the informed consent, participants will complete a medical history questionnaire to assess eligibility. Participants qualifying for the study will then be assessed for anthropometric measurements and maximal strength for the BS and BP. Participants will be provided coaching on form and movement patterns from a Certified

Strength and Conditioning Specialist, if needed. During Visit 2 (V2), participants will complete a confirmation assessment of maximal strength for both exercises. During Visit 3 (V3),

46 participants will be asked to complete two sets of three repetitions for relative loads of 30, 50,

60, and 70% of their previously determined 1-RM, for the purpose of assessing velocity.

Figure 2

Study 2 Design

Participants will complete three visits, each separated by at least 48 hours. On Visit 1, participants provide a written informed consent, followed by a medical questionnaire, anthropometrics, and a one-repetition maximum assessment. During Visits 2, participants will complete 1-RM confirmation. During Visit 3, participants will complete a velocity assessment for the BS and BP.

Procedures

The following section discusses all procedures to be utilized throughout the investigations.

Anthropometric Measures

Height and body mass will be collected for each participant during Visit 1. Both measurements will be determined using a digital clinical scale (Health-o-meter 500KL, McCook,

IL). Joint angle measurements will be taken at the knee using a goniometer to ensure a depth of

90° during the barbell BS. These joint angles will be used to position the safety bars.

1-Repetition Maximum Assessment

Maximal strength will be assessed during V1 and confirmed during V2. Participants will complete a standardized warm-up, consisting of five minutes at a self-selected intensity on an

Airdyne bike (Schwinn, Pacific Cycle, Inc., Vancouver, WA) followed by 10 bodyweight squats,

10 walking bodyweight lunges, and 10 bodyweight push-ups. If a participant does not possess enough strength to complete normal push-ups, they may be done while resting on their knees, or against a wall. Participants will then complete a 1-RM assessment for the barbell BS and BP in a superset fashion, while following guidelines established by the National Strength and

Conditioning Association (Haff & Triplett, 2015). The same Certified Strength and

Conditioning Specialist (CSCS) will oversee all 1-RM protocols to monitor proper form and consistent progression. The participant will begin by completing three warm-up sets for both the

BS and BP, with each superset separated by one minute of rest. Each set will consist of up to 10 repetitions at 50% of their estimated 1-RM (set 1), up to five repetitions at 65% of their

49 estimated 1-RM (set 2), and two to three repetitions at their estimated 80% 1-RM (set 3). This will be followed by up to five attempts at a 1-RM for both movements, with 2-3 minutes rest separating each squat and BP attempt allotting 4-6 minutes rest between 1-RM attempts for each exercise. Proper form for the BS will dictate participants must reach a position in which the top of their thigh is at least parallel to ground prior to the ascent phase. Proper form for the BP will dictate participants must reach a point of contact between their chest and the barbell prior to the ascent phase, as well as maintain five points of contact (head, both shoulders, both feet, and glutes) throughout the movement. The greatest load completed with proper form will be considered the participants.

Velocity Assessment

Velocity assessments will be completed during Visit 3. Upon arrival, participants will warm-up with five minutes at a self-selected intensity on an Airdyne bike, followed by 10 bodyweight squats, and 10 walking bodyweight lunges. This will be followed by two assessment protocols in which movement velocity will be assessed during submaximal efforts for both the

BS and BP, with the squat protocol being completed first. Following the squat protocol, the participant will be provided up to five minutes of rest and will complete a warm-up set of ten push-ups prior to the bench protocol.

Each assessment protocol will consist of two sets of three repetitions completed at 30, 50,

60 and 70% 1-RM. Participants will be provided 2-3 minutes of rest between each set. During the BS, participants will be instructed to complete the eccentric phase in a controlled manor until the top of their thigh is perpendicular to the floor and complete a temporary pause before ascending. During the BP, participants will be instructed to lower the barbell until the bar is

50 within 3cm of the sternum and complete a temporary pause before ascending. Participants will then be verbally encouraged to complete the concentric portion of the movement as explosively as possible. Participants will be required to maintain contact with the barbell and floor during the BS and five points of contact (as previously described) during the BP. Velocity will be measured during each repetition by the HUMAC360 linear position transducer (Computer Sports

Medicine Inc., Stoughton, Massachusetts). The HUMAC360 will be placed on the floor and attached directly to the barbell by a fabric strap at the furthest right portion of the grip section of the barbell. The HUMAC360 will be fixed positionally in which the retractable belts are perpendicular to the ground and in line with the path of movement during each exercise.

Velocity data for the HUMAC360 will be collected at a sampling rate of 100 Hz.

Velocity Curve Analysis

Peak velocity (PV), mean concentric velocity (MCV), and mean propulsive velocity

(MPV) will be used for the purpose of this investigation and be calculated using a customized

Excel spreadsheet (Microsoft, Redmond, WA). PV will be calculated as the maximum velocity achieved during the concentric phase of the movement (Lorenzetti, et al., 2017). MCV will be calculated as the average velocity from the initiation of the concentric phase until the barbell velocity is 0 m·s-1 (Pestana-Melero et al., 2017). MPV will be calculated as average velocity from the start of the concentric phase until the acceleration of the bar is less than the acceleration of gravity (-9.81 m·s-2) (Gonzalez-Badillo et al., 2015).

Statistical Analysis

For this investigation, dependent variables will consist of PV, MPV, and MCV. Potential differences in velocity at each submaximal load (30, 50, 60, and 70% 1-RM) will be assessed by a three factor (group x sex x intensity), within-between subjects, repeated measures analysis of variance (ANOVA). If a significant F ratio is observed, follow-up ANOVAs will be performed.

Specifically, if a 3-way interaction is observed, a 2-way ANOVA (group x velocity; sex x velocity; and group x sex) with repeated measure for each independent variable will used.

Moreover, if a 2-way interaction is observed, a 2-way ANOVA (group x velocity; sex x velocity; or group x sex) will be conducted while collapsing the third variable. If significance is observed, independent t-tests will be utilized. If a main effect of group, intensity or sex is observed, a least significant difference (LSD) pairwise comparison will be utilized.

Potential Limitations and Contingencies

The following section discusses potential limitations and contingencies the investigation may encounter.

Potential Limitations

Training status of participants may present possible limitations to this investigation. The use of inexperienced individuals may lead to the initial 1-RM assessment not accurately reflecting maximal strength of the individual as a result of poor form and movement mechanics.

To attenuate both potential limitations, a Certified Strength and Conditioning Specialist will provide form coaching during V1, and a confirmation 1-RM assessment will be completed during V2.

Additionally, the resistance training experience of athletes may vary depending on sport.

To decrease the potential variability in experience as well as omit athletes with limited prior resistance training, athletes will be required to have at least six months (≥ 3 days per week) of prior resistance training experience.

When using free weight during the barbell BS and BP, the potential for horizontal displacement is present, which may affect velocity data collected from the linear position transducer. This could be mitigated through the use of a Smith machine; however, the use of free weight provides greater external validity. Furthermore, Loturco et al. (2017) observed no difference in MPV at relative submaximal loads between the Smith machine and free-weight exercises. Therefore, the use of free weight should provide similar velocity data to that of a

Smith machine, while also increasing practical application. Therefore, we contend the use of free weight exercise is the most appropriate method to address this question.

Contingencies

Given the nature of resistance exercise, weight will be placed on the superior aspect of the back, as well as be controlled by upper extremities. This loading of the spine and upper extremities may present risk of injury, though would not be any different than a traditional training session. Moreover, athletes may have greater risk of injury during external activities during practice and/or competition. In the event that a participant is injured during the investigation, the participant will be removed from the study.

Within this investigation, there is a possibility of missing data points as a result of discomfort to the participant. If this outcome presents itself for any participant, a mixed model regression analysis will be utilized to account for missing data. Additionally, non-normally

53 distributed data will be analyzed using a mixed model regression analysis, as normality is not an assumption of mixed-model regression analysis.

APPENDICES

APPENDIX A

FUTURE STUDY ABSTRACT

Appendix A

Future Study Abstract

Maximal strength for individuals may vary between training sessions as a result of various factors, potentially requiring autoregulation of load. With a previously demonstrated relationship between load and velocity, load-velocity profiles can be established and used to provide velocity ranges and predict relative loads. As a result, velocity-based training has been used as an autoregulation technique, deeming velocity as the dictator of exercise intensity. While previous investigations have demonstrated men and women to have different velocities at submaximal loads and differing velocity profile slopes, to date no previous research has assessed the affects training status and/or sport participation has on load-velocity profiles. Therefore, the purpose of this investigation is to assess load-velocity profiles of inexperienced, non-athlete recreationally active, and athlete individuals, as well as sex differences between groups. To achieve this, we intend to recruit up to 25 men or women for each group to participate in our study. Participants will be asked to report to the laboratory on three separate occasions, each separated by at least 48 hours. In the first visit (V1) participants will be asked to complete a maximal strength assessment (1-RM) for the barbell back squat and bench press. Participants will receive coaching on form and movement patterns if needed. During Visit 2 (V2) participants will be asked to complete a confirmation assessment 1-RM for both exercises. During Visit 3 (V3) participants will be asked to complete a velocity profile assessment for each exercise by completing two sets of three repetitions for relative loads

of 30, 50, 60, and 70% of their previously determined 1-RM. During each repetition, velocity will be measure by the HUMAC360 linear position transducer, collecting at a sampling rate of 100 Hz. Peak velocity, mean concentric velocity, and mean propulsive velocity will be calculated using a customized Excel spreadsheet. Difference in velocity variables at each relative load will be analyzed by a three-way (group x sex x intensity) within-between subjects repeated-measures analysis of variance (ANOVA).

APPENDIX B

KENT STATE APPROVED IRB

Appendix B

Kent State Approved IRB

APPENDIX C

INFORMED CONSENT

Appendix C

Informed Consent

APPENDIX D

MEDICAL HEALTH HISTORY QUESTIONNAIRE

Appendix D

Medical Health History Questionnaire

APPENDIX E

RECRUITMENT FLYER

Appendix E

Recruitment Flyer

APPENDIX F

RECRUITMENT SCRIPT

Appendix F

Recruitment Script

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