THE EFFECTS OF INTERNAL AND EXTERNAL FOCUS OF ATTENTION CONDITIONS THE PUNCHING IMPACT FORCE AND ELECTROMYOGRAPHY ACTIVITY IN BOXERS

______

A Thesis

Presented to the

Faculty of

California State University, Fullerton ______

In Partial Fulfillment

of the Requirements for the Degree

Master of Science

in

Kinesiology ______

By

Robert Mendoza Jr.

Thesis Committee Approval:

Joao A. Barros, Department of Kinesiology, Chair Lenny D. Wiersma, Department of Kinesiology Pablo B. Costa, Department of Kinesiology

Fall 2017

ABSTRACT

When an athlete adopts an internal focus of attention, their performance may be hindered. Conversely, when an athlete adopts an external focus of attention, performance has been shown to be enhanced. The purpose of this study was to investigate the effects of internal and external focus of attention conditions on punching impact force and electromyography (EMG) of boxers. Thirteen male boxers (M weight = 168.15), who were free of musculoskeletal injury and sensory or motor dysfunction, volunteered to participate for this study. At the end of the data collection, participants completed a questionnaire to check adherence to focus instructions. No significant difference in punching impact force or EMG activity was found between internal and external focus conditions (p = .166). The questionnaire data indicated participants possibly did not pay attention to key elements of the instructions, specifically the instructions to focus on the punching pad or the arm, and focused on more procedural aspects of the instruction, such as the timing of the punches. Although it has been suggested in previous research that the skill level of the performers may influence the effectiveness of external focus instructions in enhancing performance, it is unlikely that this factor played a role in the current study.

Based on the questionnaire data, it is more likely that the delivery of the instructions did not sufficiently highlight the key elements of the instructions.

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TABLE OF CONTENTS

ABSTRACT ...... ii

LIST OF TABLES ...... v

LIST OF FIGURES ...... vi

ACKNOWLEDGMENTS ...... vii

Chapter 1. INTRODUCTION ...... 1

2. REVIEW OF LITERATURE ...... 4

An Overview of the Importance of ...... 4 Research on Performance Enhancement in Combat Sports...... 5 Attentional Focus Cues on Performance ...... 7 Constrained Action Hypothesis ...... 9 Research Question ...... 11 Purpose...... 11 Hypothesis ...... 12

3. METHODS ...... 13

Participants...... 13 Task ...... 13 Instruments...... 14 EMG Signal Processing ...... 15 Procedures ...... 15 Data Analyses ...... 17

4. RESULTS ...... 19

Impact Forces ...... 19 Relative Impact Forces ...... 19 Effects of Learning on Relative Impact Force ...... 20 EMG RMS ...... 21 Mean EMG Pectoralis Major ...... 21

iii Mean EMG Triceps Brachii ...... 22 Questionnaire Response ...... 23

5. DISCUSSION ...... 25

APPENDICES ...... 30

A. INFORMED ...... 30 B. PUNCHING SCRIPT ...... 34 C. POST EXPERIMENTAL QUESTIONNAIRE ...... 37 D. OPERATIONAL QUESTIONNAIRE ...... 38 E. SPSS OUTPUT 1 RELATIVE IMPACT FORCE ...... 39 F. SPSS OUTPUT 2 IMPACT FORCE FOR FIRST AND SECOND SET OF PUNCHES ...... 40 G. SPSS OUTPUT 3 RELATIVE EMG RMS FOR PECTORALIS MAJOR .. 41 H. SPSS OUTPUT 4 RELATIVE EMS FOR TRICEPS BRACHII ...... 42

REFERENCES ...... 43

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LIST OF TABLES

Table Page

1. Participants’ Answers to Post-Experimental Questionnaire ...... 24

v

LIST OF FIGURES

Figure Page

1. StrikeMate ...... 15

2. Mean relative impact force during internal and external focus of attention conditions ...... 20

3. Mean relative impact force in the first set of punches and last set of punches. ... 21

4. Mean EMG RMS normalized by MVC for the pectoralis major and triceps brachii during internal and external focus conditions ...... 22

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ACKNOWLEDGMENTS

To the friends who have entered in and out of my life, but more specifically to the ones who have remained and struggled alongside with me, I cannot thank you enough for your help. Thank you Mojgahn, Albert, Paz, Kevin, Llata, Jose, and

Robert Salatto. Near or far, I have always known I could count on you all, 100% of the time, every time. Thank you to the person, or people, who rejected me from attending

CSULB. You did me the biggest favor, EVER. Conversely, thank you to the person, or people, who admitted me on a conditional basis to CSUF.

Thank you, Dr. Coburn, for giving me the opportunity to attend graduate school at

CSUF. Thank you to my committee chair Dr. Barros, and committee member Dr. Costa.

Dr. Gradilla, gracias por la confianza que me diste cuando era un joven empezando en la universidad, y por el apoyo que me has dado durante todos mis años en CSUF. Dr.

Llewellyn and Dr. Gleaves, thank you for sharing your passion for and philosophy, for challenging me in your classes, for making me believe I could succeed, and selecting me to go on a trip of a lifetime. I know that I’ll never walk alone. To my sport psychology parents, Dr. Statler and Dr. Wiersma. Because of your passion, energy, intelligence, hard work and kind hearts, I have decided to dedicate my life to Sport

Psychology. What you both have done for me would take lifetimes to repay, and there are not enough words to express how grateful I am for the two of you. One day I hope to be just like the both of you, the best.

vii To all my dozens and dozens of cousins, to my aunts and uncles, my Nino y Nina, ama, grandma, close and distant relatives, your support was everything I ever needed, and you gave it to me unequivocally. Finally, to my mother and father, I love you both very much. You have given me everything I ever needed and wanted. Your tireless hard work, sacrifices, and unconditional love allowed me the opportunity to accomplish this grand feat. Without the both of you, I would not be where I am today. This thesis is a culmination of your love and support of me. “I,” did not do this. WE, did this. Los quiero mucho.

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CHAPTER 1

INTRODUCTION

According to Boddy (2008), combat sports can be traced back to the fourth millennium B.C. to Ancient . In , athletes competed in a fighting sport similar to present day and mixed at important religious festivals such as Nemean, Pythian, Isthmian and Olympia (Boddy, 2008). By becoming victorious in the sport at one of these festivals, winners could find an improvement in their own social status, as well as large rewards of money (Boddy, 2008). While considerable time has passed since the ancient Greek , sports such boxing and remain today.

Winners of important fights can expect to receive large sums of money as well as improvements in their social class. According to Rafael (2015), boxer Floyd Mayweather

Jr. received one-hundred-and-eighty-million dollars following his win over Manny

Pacquiao. According to Okamoto (2016), Ultimate Fighting Championships fighter

Conor Mcgregor earned three million dollars for his rematch against . With the possibility of earning such large amounts of money, it is imperative that fighters become skilled in all aspects of their respective .

An athlete’s ability to produce maximal force is an important component to success in combat sports (James, 2015). One of the ways researchers have sought to increase athletes’1 force production is by manipulating their focus of attention (for a

2 review, see Wulf, 2007). An internal focus of attention directs the athlete’s attention to their own body, while an external focus of attention directs the athlete’s attention to their intended movement effect. Several authors have demonstrated an increase in performance in tasks that required maximum force production when performers use an external focus of attention (Porter, Anton, Wikoff, & Ostrowski, 2013; Vance, Wulf, Tollner, McNevin,

& Mercer, 2004; Wulf & Dufek, 2009; Wulf, Dufek, Lozano, & Pettigrew, 2010; Wulf,

McNevin, & Shea 2001)

The beneficial effects of external focus of attention conditions have been explained by the constrained action hypothesis (Wulf et al., 2001). When an individual adopts an internal focus of attention, they unintentionally disrupt the autonomy of their movement. Conversely, adopting an external focus of attention allows for a more fluid and automatic movement (Wulf, 2007). Electromyography (EMG) data is considered the best source of support for the constraint action hypothesis. Generally, when individuals use an external focus of attention, EMG activity in the muscles involved in the action is decreased compared to situations when individuals use an internal focus of attention

(Vance et al., 2004; Wulf et al., 2010).

Recently, Halperin, Chapman, Martin, and Abbiss (2016) investigated the effects of different focus of attention instructions on the punching impact force of combat athletes. The results indicated an increased performance during the external focus of attention condition in a variety of types of punches. The authors stated the results could be explained through the constraint action hypothesis. However, no EMG data was used in the study.

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Therefore, the purpose of this study was to investigate the effects of internal and external focus conditions on punching impact force and EMG activity in boxers. Based on current research, we hypothesized that there would be a significant difference in punching impact force between internal and external focus conditions. Specifically, we expected that boxers would produce higher punching impact forces in the external focus condition than in the internal focus condition. We also hypothesized that there would be a significant difference in EMG activity in the pectoralis major and triceps brachii during punching in the internal and external focus conditions. Lastly, based on current research involving attentional focus and EMG activity, we expected the internal focus condition to elicit higher levels of EMG activity compared to the external focus condition.

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CHAPTER 2

REVIEW OF LITERATURE

An Overview of the Importance of Combat Sports

Pottery found in archeological sites suggests combat sports, similar to modern boxing, existed in Ancient Mesopotamia (Boddy, 2008). In Ancient Greece, athletes participated in combat sport competitions with the highest prestige at religious festivals such as at Isthmia, Nemea, Pythia, and at Olympia (Boddy, 2008). One of these festivals that still have relevance for today’s audiences are the .

Preparation for the Ancient Olympic games was vigorous, and required Greek athletes to train amongst their peers in a gymnasium for a month prior before the Games, and from there only the best would be selected to compete, the winners of those games would go on to live the rest of their lives as walking gods (Kyle, 2014).

Even though the first Ancient Olympic games took place in 776 B.C. (Finley &

Pleket, 2012), boxing in the United States during the 18th and was just in its infancy. Successful fighters received recognition from society for their fighting prowess.

In his book, Gorn (1986) describes glory fighters received in the 18th and 19th centuries:

“Boxers in the received patronage from great men, and in return the exploits of fighters confirmed the love of the old upper class for valor” (Gorn, 1986, p.

67). During the 19th century in the United States, fighters received support from people of their same ethnic background, as well as support from people who lived in the same

5 area as . According to Gorn (1986), “Boxing promoted patriotism as well as a national ethos of courage and fair play” (Gorn, 1986, p. 57). During fights in this time period, people would place the biggest bet possible for their fighter to show support, but also because “gambling was a mark of courage” (Gorn, 1986, p. 140). As the sport continued to grow, the amount of money that could be made also grew, and in May of

2015, money generated from a boxing fight reached an all-time high.

On May 3rd, 2015, in Las Vegas Nevada, Floyd Mayweather Jr. defeated Manny

Pacquiao in a twelve-round boxing match to claim the .

For his efforts, Mayweather earned close to one hundred and eighty million dollars, for a fight that lasted thirty-six minutes (Rafael, 2015). Along with boxing, Mixed Martial Arts

(MMA), primarily organized by Ultimate Fighting Championships (UFC), has also dramatically grown in popularity. While UFC was originally purchased for two million dollars in 2000, the company was sold for four billion dollars in July of 2016 (Rovell

&Okamoto, 2016). Given the significance of combat sports, evidenced by the monetary value of prizes, value of companies that organize combat sports, and mass appeal, it is imperative that fighters find new ways to gain the competitive edge over their opponents.

Research on Performance Enhancement in Combat Sports

Combat athletes are continuously looking for ways to gain the upper hand over their competitors. Since combat sports tend to be physiologically demanding (Jay, 2013), rely on the anaerobic energy system (Tack, 2013), as well as the aerobic energy system

(Ruddock, Wilson, Thompson, Hembrough, & Winter, 2016), and on the athlete’s ability to produce maximum force (James, 2015), most of the research aimed at improving athletes’ performance in combat sports focused has highlighted the importance of

6 physical fitness to the success in these sports. In that sense, the importance of other aspects of performance, like psychological skills, have been neglected. For example,

Simpson and Wrisberg (2013) stated that despite considerable research surrounding the sociology of the sport of boxing, very little research has been done on the, evidently high, psychological demands of the sport.

To further understand the experience of boxers from a psychological perspective,

Simpson and Wrisberg (2013) used an existential phenomenology approach to interview nine British professional boxers about their experience preparing for a fight. The researchers were able to identify six recurring themes: Achieving Potential, Preparing,

Sacrifice, Finding Support, Fearing, and Love/Hating (Simpson & Wrisberg, 2013).

Other authors focused on MMA athletes’ self-regulatory skills, as they relate to success in the sport. Massey, Meyer, and Naylor (2015), described self-regulation as “the ability of an organism to manage thoughts, feelings, and behaviors, and delay gratification to achieve a longer-term objective” (p. 193). The themes identified included: Behavioral

Processes of Change, Embodied Emotions, and Psychological Strategies.

Although there is increasing insight into the psychological experiences of combat athletes (Massey, Meyer, & Naylor, 2015; Simpson, & Wrisberg, 2013), there is still limited scientific literature addressing the improvement of athlete’s performance focused on variables other than fitness related variables. One of these variables is focus of attention, which has recently been used to increase punching impact force in combat sports (Halperin, Chapman, Martin, & Abbiss, 2016).

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Attentional Focus Cues Effect on Performance

Verbal instructions are an easy way to produce changes in motor performance.

Verbal instructions can be used as a guidance technique, as feedback, and as a strategy to direct an individual’s attention to something specific (Rose & Christina, 2007). Recently, research has specifically investigated the effects of different focus of attention on the learning and performance of motor skills (Wulf, 2007). Specifically, research compares the effects of an internal focus of attention to the effects of an external focus of attention on the performance and learning of motor skills. An internal focus of attention directs the performer’s attention to her own body (Wulf, 2007). For example, when a coach instructs a swimmer to pay attention to the position of their during the recovery phase of the front crawl, the coach is using an internal focus of attention. On the other hand, if the coach instructs the swimmer to focus on pushing off the wall quickly during a flip-turn, the coach is using an external focus of attention. Several authors have demonstrated that an external focus of attention produces better learning and performance outcomes.

It is also suggested that the effects of an external focus of attention are so powerful that the improvement in performance is immediate (Wulf et al., 2000). In the second experiment of their study, Wulf and colleagues (2000) compared the effects of paying attention to the movement of the arms (i.e., internal focus) to paying attention to the movement of the club (i.e., external focus) in the acquisition of a golf pitch shot to a target. Though there was no difference between conditions on the pre-test, the benefits of the external focus of attention were evident on the first practice block based off of scoring.

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Several studies corroborate the initial findings by Wulf and colleagues (2000).

Wulf, Zachary, Granados, and Dufek (2007) investigated the effects of attentional focus cues on the performance of a maximal force production task (i.e., vertical jump task).

Each participant performed five jump trials in each focus condition: external, internal, and control. In the control condition, participants were given no focus instruction. In the internal focus condition, participants were told to focus on their fingertips. In the external condition, participants were told to focus on the rungs of the apparatus. The results indicated participants jumped higher when using an external focus of attention, rather than using an internal focus or no focus at all. In a follow-up study the authors used kinetic analyses of the jumps. The results confirmed an external focus of attention produced better jump performance compared to the other conditions, and the improved performance was reflected in the position of the center of mass. In Wulf and Dufek

(2009) also used kinetic data to further detail the benefits of an external focus of attention. Specifically, the authors examined the effect of attentional cues on vertical jump performance. Participants used the same task and the same focus instructions as used in Wulf and colleagues (2007). In addition to showing higher jump performance under an external focus, the data indicated that participants showed higher center of mass displacement, and greater joint moments.

Other authors demonstrated the advantages of an external focus over an internal focus on the long jump (Ducharme, Wu, Lim, & Porter, 2015; Porter et al., 2013).

Additionally, an external focus that is further away from the body has produced even better results (Mckay & Wulf, 2012). For example, Porter and colleagues (2013) compared a control condition, internal focus condition (“When you jump, focus on

9 extending your knees as rapidly as possible”), an external focus condition that was near the body (“When you jump, focus on jumping as far past the start line as possible”), and an external focus condition that fixated on a target that was away from the body (“When you jump, focus on jumping as close to the cone as possible”). Results indicated the external focus on a target produced the greatest jump distances followed by the external focus condition near the body, then the control condition and then the internal focus condition.

Even tasks that are technique focused have also benefitted from an external focus of attention. For example, Abdollahipour, Wulf, Psotta, and Palomo Nieto (2015) focused on . Participants were asked to complete a 180° jump in the air while simultaneously crossing their hands across their chest. Under the external focus condition, the gymnasts were instructed to focus on the direction in which the piece of yellow tape was pointing to during their jump. In the internal focus condition, they were told to focus on the direction in which their hands were pointing to during their jump. In the control condition, they were not given any specific focus instruction. The results of the study suggested that jump height was higher in the external focus-condition compared to the internal focus- and control- conditions. Also, participants received fewer deductions in the external condition compared to the other conditions.

Constrained Action Hypothesis

The beneficial effects of the external focus of attention conditions have been explained by the constrained action hypothesis. It is suggested that when an individual focuses on the movement of their body (i.e., an internal focus of attention), they unintentionally intrude on the autonomy of their movement. Conversely, focusing on the

10 movement effect (i.e., an external attentional focus) allows for a more fluid and automatic movement (Wulf, 2007). In other words, by focusing on their desired movement effect, they allow for fast, reflexive, uninterrupted movements, which produce improved performance and learning.

In one of the first studies to investigate the issue, Vance et al. (2004) examined the effects of different focus of attention on the performance of a bicep curl. In this case, electromyography (EMG) data was also examined. For the internal focus condition, participants were instructed to concentrate on their biceps muscles. In the external focus condition, they were instructed to concentrate on the curl bar. Electrodes were positioned on the skin above the belly of the right biceps brachii muscle and triceps brachii muscle.

Results indicated that velocity was greater in the external compared to the internal focus condition. Interestingly, EMG activity under external focus of attention was reduced compared to the internal focus condition. In a follow up experiment, researchers included a metronome to prescribe movement time. The results of Experiment 2 also suggested that adopting an external focus is more beneficial in regard to energy efficiency and for movement compared to an internal focus.

Several other studies followed and showed similar results. Zachry, Wulf, Mercer and Bezodis (2005) were able to demonstrate improved accuracy during free throws and reduced muscle activity (EMG) in association with an external focus condition in comparison to an internal focus condition. Marchant, Greig, and Scott (2009) demonstrated by an external focus of attention produced greater torque and lower EMG during a biceps curl task compared to an internal focus condition. Lohse, Sherwood, and

Healy (2010) demonstrated increased accuracy and reduced EMG associated with an

11 external focus of attention during a throwing task compared to an internal focus of attention. And finally, Wulf et al. (2010) found that vertical jump increased and EMG data decreased in association with an external focus of attention.

Research Question

It is clear based on the literature available that an external focus of attention produces performance benefits to many “real world” and sport tasks. Given the highly competitive nature of combat sports, it is expected that this manipulation would also be tested in that context. Recently, Halperin et al. (2016) have investigated the effects of different focus of attention on the punching impact force of combat athletes. Elite and near elite combat athletes were asked to produce three different kinds of punches under internal and external focus conditions. Specifically, under the internal focus condition participants were told to “Focus on moving your arm as fast and as forcefully as you possibly can”. While under the external focus condition, participants were told to “Focus on punching the pad as fast and as forcefully as you possibly can”. The results indicated that the external focus condition produced greater velocity and impact forces. The authors speculate that the benefits observed should be attributed to a more autonomous movement pattern associated with the external focus condition, as suggested by the constrained action hypothesis. However, the authors do not include data that can support those claims. Would the benefits of associated with an external focus of attention in punching be associated with lower EMG activity?

Purpose

The purpose of the study is to investigate the effects of internal and external foci conditions on the punching impact force and EMG activity in boxers.

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Hypothesis

Based on current research, we hypothesized that there would be a significant difference in punching impact force between internal and external focus conditions.

Specifically, we expected that boxers would produce higher punching impact forces in the external focus condition than in the internal focus condition. We also hypothesized that there would be a significant difference in EMG activity in the pectoralis major and triceps brachii during punching in the internal and external focus conditions. Lastly, based on current research involving attentional focus and EMG activity, we expected the internal focus condition to elicit higher levels of EMG activity compared to the external focus condition.

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CHAPTER 3

METHODS

Participants

Thirteen male boxers were recruited for this study. Participants were recruited by in class announcements as well as by word of mouth. All participants were male between the ages of 18-40 (M = 24.69 yrs., SD = 4.93) years old. Participants were required to have a minimum of three years of boxing experience (M = 8.23 yrs., SD = 4.35) as well as also partaking in vigorous at least twice a week for the six months prior to data collection. All participants performed the task in the right handed, orthodox punching . All participants were right hand dominant for punching. Participants were free from any musculoskeletal injury and sensory or motor dysfunction. Participants signed informed consent forms prior to participation in the study, in compliance with the university's Institutional Review Board. Participants were aware they would be performing a punching task, but were unaware of the specific purposes of this study.

Task

Participants were asked to hit the StrikeMate with their dominant punching arm with maximum impact force. They were positioned in front of the target, at arm’s length, and used their preferred fighting stance (i.e., orthodox). Participants were required to perform a straight punch technique for the task. Participants performed the task under two

14 attentional focus conditions (i.e., internal and external focus) described in detail in the

“Procedures” section.

Instruments

For this study, a StrikeMate device (StrikeMate™, Research Limited,

Norwich, United Kingdom) was utilized (see Figure 1). The StrikeMate is a cuboid

(305 mm wide by 305 mm tall by 255 mm deep), padded device that uses two accelerometers and custom software to measure and record the peak impact force (Figure

1). The StrikeMate was fixed at a column with straps at the participant’s shoulder height.

A modified version of the questionnaire (Appendix C) used by Post, Barros, and

Wrisberg (2011) was administered to participants following completion of all punching trials. The questionnaire included questions to verify compliance with and effectiveness of instructions. Specifically, participants were asked to rate, on a scale from one to four,

(a) the extent to which they followed the instructions they were given (“not at all” to

“always”); and (b) how effective they felt the instructions were (“not at all” to “highly”).

Any participant who did not give a rating of “4” to the first question was asked to describe what other types of focus he used. Participants were also asked which of the focus conditions they found more helpful.

Additionally, pre-amplified, bipolar surface EMG electrodes (EL254S; Biopac

Systems Inc., Santa Barbara, CA; gain = 350) were used on the pectoralis major and triceps brachii. Placement of the electrodes (1 3/8”) followed procedures described by

Dinn and Behm (2007) and Tillaar and Saeterbakken (2014), and are detailed in the

“PROCEDURES” section. EMG activity was recorded simultaneously with a Biopac data acquisition system (MP150WSW; Biopac Systems Inc.) interfaced with a laptop

15 computer (Dell Inc., Round Rock, TX) using proprietary software (AcqKnowledge version 3.7; Biopac Systems Inc.).

EMG Signal Processing

The EMG signal was preamplified (gain 1000 ×) using a differential amplifier

(EMG 100, Biopac Systems Inc., Santa Barbara, CA; bandwidth = 1-5000 Hz). EMG activity was sampled at 1000 Hz, filtered with band-pass filter (10–500 Hz). The amplitude of the signals was expressed as root mean square (RMS) values, and then normalized to the highest recorded value that occurred during the maximum voluntary contraction (MVC).

Figure 1. StrikeMate.

Procedures

For this study, participants were recruited by in class announcements and by word of mouth at CSUF and gyms around Orange County, California. Data collection occurred in a secluded and quiet location outside the Kinesiology and Health Sciences building at

California State University, Fullerton (CSUF). Data collection was completed individually in one session that lasted approximately 60 minutes. Participants were asked to wear athletic attire that they normally wear in training sessions. Upon arriving,

16 participants read and signed the informed consent form. Participants then completed a self-selected warm-up which included dynamic stretches and shadow boxing and lasted approximately 15 minutes.

Following pilot sessions, it was decided that the biceps brachii was substituted for the pectoralis major Participants were then fitted with the EMG electrodes using similar protocols to Dinn and Behm (2007) and van den Tillaar and Saeterbakken (2014). EMG electrodes were placed on the pectoralis major (approximately 4 cm medial to the axillary fold) and triceps brachii muscles (midway between the acromion and olecranon processes on the triceps brachii) of the punching arm). All electrodes were placed in line with the direction of fibers of the corresponding muscle. The skin was shaved and washed with alcohol prior to the placement of the electrodes. Following the placement of the EMG electrodes, participants performed a maximal voluntary contraction (MVC) test to measure the muscle activity of the pectoralis major, as well as the triceps brachii.

Following this test, participants were fitted with boxing gloves then familiarized with the

StrikeMate device. They were then positioned at arm’s length, facing the StrikeMate. from the target was determined by having each participant touch the StrikeMate target, while wearing the boxing gloves, and step back as far as possible without losing contact. Once they reached the appropriate distance, participants assumed their preferred fighting stance (i.e., orthodox). Tape was also used to mark the foot placement of the participants, to ensure that they performed from the same position for both sets of punches. Participants were then instructed to punch the StrikeMate device, at their own pace, three times using 50% of their perceived maximal punching force to become familiar with the equipment (i.e., target and EMG electrodes). Participants were

17 instructed to use the straight punch technique throughout the duration of the study and to use their maximum effort during each of the trials.

Participants performed 20 punches in total (ten in each experimental condition).

During the internal focus of attention condition, participants were told to “Focus on moving your arm as fast and as forcefully as you possibly can”. During the external focus of attention condition, participants were told to “Focus on punching the pad as fast and as forcefully as you possibly can”. Halperin et al. (2016) used the same instructions. In their study combat athletes had increased impact force during punching when using the external focus of attention instruction compared to when the internal focus of attention instruction was used. The order in which participants completed the conditions was counterbalanced. Participants were given approximately three minutes in between conditions and five seconds in between trials to minimize fatigue. Prior to the initiation of each condition, the focus instructions were read aloud to the participants who were told to follow them for the set of ten punches.

Data Analyses

Five dependent variables were calculated: relative impact force, relative impact forces for first set of trials (FIRST SET), relative impact forces for second set of trials

(SECOND SET), relative EMG activity of the pectoralis major (PEC), and relative EMG activity of the triceps brachii (TRI). Only the last seven trials performed under each condition were used in the analyses. The first three trials were discarded to further avoid learning effects. The dependent variables were calculated for each condition by averaging the scores obtained in the last seven trials of each set of ten punches. SPSS Statistics

Software Version 24 (IBM Predictive Software) was used for the data analyses.

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Significance was set at p < 0.05.In addition, descriptive statistics for the questionnaire responses and qualitative comments are presented.

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CHAPTER 4

RESULTS

Impact Forces

Impact force data is presented in this section. Since impact force is dependent on participants’ body weight, impact force was normalized by participant’s body weight

(relative impact force). Relative impact force was calculated for every punch by dividing the StrikeMate impact force output by the participants’ body weight in kilograms. Impact units are presented in Franklins (f), a unit of measure that has been created by the manufacturer of the StrikeMate to calculate punching impact force.

Relative Impact Force

Figure 2 illustrates mean relative impact force during internal and external focus of attention conditions. The mean relative impact force under the internal focus condition was 172.44 (f) (SD = 49.08). The mean impact force under the external focus condition was 192.19 (f) (SD = 74.19). A paired-samples ttest was conducted to compare absolute impact force under the internal focus of attention condition and the external focus of attention condition (t = -1.476; df = 12; p = .166). The results of the t-test indicated there was no significant difference in mean relative impact force between internal and external focus conditions (p < .05).

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Relative Impact Force 250

200

150

100

50

0 INTERNAL EXTERNAL .

Figure 2. Mean relative impact force during internal and external focus of attention conditions (Internal SD = 49.08) (External SD = 74.19).

Effects of Learning on Relative Impact Force

To examine whether learning occurred between the first set of trials and the second set of trials, absolute and relative impact forces obtained in the first set of trials

(regardless of focus condition instruction) were compared to absolute and relative forces obtained in the second set of trials (regardless of focus condition instruction).

Figure 3 illustrates the mean relative impact force in the first set of punches and last set of punches. The mean relative impact force of the FIRST SET of punches was

189.81(f) (SD = 60.35). The mean relative impact force in the SECOND SET of punches was 174.82 (f) (SD = 66.04). A paired-samples ttest was conducted to compare relative impact force between the first and second set of punches (t = 1.079; df = 12; p = .302).

The results of the t-test indicate there was no significant difference in mean relative impact force between internal and external focus conditions (p < .05).

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Relative Impact Scores 200 180 160 140 120 100 80 60 40 20 0 FIRST SET LAST SET

Figure 3. Mean relative impact force in the first set of punches and last set of punches (First Set SD = 60.35) (Second Set SD = 66.04).

EMG RMS

EMG data was collected for all punches performed by the participants. The amplitude of the signals was expressed as root mean square (RMS) values, and then normalized to the highest recorded value that occurred during the maximum voluntary contraction (MVC). Only the EMG RMS of the last seven trials were included in the analysis. Additionally, it must be noted that three individual readings for the pectoralis major were unable to be used for this data because of technical difficulties.

Mean EMG Pectoralis Major

The mean relative EMG activity for the pectoralis major in the internal condition was 4.29 (SD = 6.3423). The mean relative EMG activity for the pectoralis major in the external condition was 1.2359 (SD = .3036). A paired-samples t-test was conducted to compare relative EMG activity under the internal focus of attention condition and the external focus of attention condition (t = 1.7; df = 12; p = .115). The results of the t test

22 indicate there was no significant difference in mean relative EMG activity for the pectoralis major between internal and external focus conditions(p < .05) (Figure 4).

Mean EMG Triceps Brachii

The mean relative EMG activity for the triceps brachii under the internal focus condition was 1.6482 (SD = 2.3363). The mean relative EMG activity for the triceps brachii under the external focus condition was 1.7293 (SD = 2.0453). A paired-samples t-test was conducted to compare relative EMG activity for the triceps brachii under the internal focus of attention condition and the external focus of attention condition

(t = -1.111; df = 12; p = .288). The results of the t test indicate there was no significant difference in mean relative impact force between internal and external focus conditions

(p < .05) (Figure 4).

EMG RMS (normalized by MVC) 5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 InternalPec ExternalPec InternalTri ExternalTri

Figure 4. Mean EMG RMS normalized by MVC for the pectoralis major and triceps brachii during internal and external focus conditions (Internal Pec SD = 6.3423, External Pec SD = .3036, Internal Tri SD = 2.3363, External Tri SD = 2.0453).

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Questionnaire Responses

Following the conclusion of the two sets of punches, participants completed a four-item questionnaire (Appendix C). Participants used a Likert scale (1–4) to answer the questions. The mean in Question 1 (“On a scale of one to four, rate the extent to which you followed the directions you were given?”) was 3.85 (SD = 0.37). The mean score in Question 2 (“On a scale of one to four, how effective did you find the instructions to be?”) was 4.00 (SD = 0.00). The participants’ answered follow up questions if they did not rate a “4” for either of the above questions. Specifically, participants were asked to

“Please state what you did in fact focus on during the punching trials?” Additionally, participants were also asked, “Which focus instruction did you find more helpful?” The answers to the follow up questions are presented in Table 1.

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Table 1. Participants’ Answers to Post-Experimental Questionnaire

ID Question 3 Question 4

1 N/A The maximal force test instructions.

Being told 10 punches per round. I didn't 2 N/A even notice.

The one I found the most helpful was the 3 N/A description of time in between punches.

5 N/A Punch fast and powerful

7 N/A To follow the buzzer in each time to punch.

At times I focused more on the buzzer I found it to be the most helpful when asked 8 than the instructions to punch as to punch the bag as quickly and as forcefully as possible forcefully as possible.

9 N/A All

The one professor said for the last set of 10 N/A punches. (External)

1st directions should be punch through the 11 Moved a little too much. bag as hard/fast. (KO punch) and should be called "arm-punch"

Being told step by step what to do. How to 12 N/A punch and how fast and hard I was allowed to punch.

13 N/A All of them.

14 N/A Focusing on the target

The second one punch the target the 15 N/A hardest.

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CHAPTER 5

DISCUSSION

Previous research in attentional focus has consistently produced evidence to suggest that an external focus of attention is beneficial to performance when compared to an internal focus of attention (Wulf, 2007). The benefits of an external focus of attention have been attributed to the constraint action hypothesis, that is, reduced muscle activity which would in turn produce a more automatic and efficient movement (Wulf et al.,

2001). Conversely, an internal focus of attention directs a performer’s attention to a specific element of a complex movement, which unintentionally disrupts the automatic processes that control movement (Wulf et al., 2001). The purpose of the current study was to investigate the effects of internal and external focus conditions on the punching impact force and EMG activity of boxers. The present study extends previous work by

Halperin et al. (2016) by verifying if, indeed, the beneficial effects associated with external focus of attention could also be explained by the constrained action hypothesis.

Our hypothesis for this study was twofold. We first hypothesized that an external focus of attention would result in higher impact force when compared to an internal focus of attention. Secondly, we hypothesized that the EMG activity for punches performed in the external focus condition would exhibit a lower level of muscular activity compared to the internal focus condition.

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Neither of these hypotheses were supported. There was no difference in impact force, nor in EMG activity of the triceps brachii and pectoralis major muscle of the punching arm between subjects in either focus condition. These present results are contrary to the results described in most of the research in the area of attentional focus.

Although not as frequent, some studies have also not found typical attentional focus research results (Porter & Sims, 2013; Winkelman, Clark, & Ryan, 2017), as was the case in this present study.

Porter and Sims (2013) examined how attentional focus influences sprint speed in collegiate players. Faster sprint times under a controlled condition when compared to an external or internal focus of attention. For the purposes of this study, the control group did not receive any instruction manipulating focus, rather, they were specifically instructed to just run with maximum effort. The researchers suggest that when working with an expert population, it may be more beneficial to not give a specific instruction to adhere to, allowing participants to self-select their preferred focus, which allowed for fast instinctive movement.

Winkelman et al. (2017) examined the effect of different focus of attention conditions on different types of collegiate athletes. In the first experiment, the researchers found that an external focus of attention in collegiate soccer players resulted in significantly faster sprint times when compared to an internal focus of attention. In the second experiment, while using the same protocol as experiment one, researchers utilized a group of highly experienced sprinters, as opposed to collegiate soccer players. Unlike experiment 1, researchers found no difference in sprint times when comparing the internal and external focus conditions. The researchers suggest that in highly skilled

27 populations, participants likely adopt a “normal focus,” which has been practiced repeatedly through training, which leads to superior performance regardless of condition or cue. Conversely, participants who have a low skill level have not yet developed the appropriate movement cues that enhance movement.

Although Porter and Sims (2013) and Winkelman et al. (2017) speculate that the participants in their studies had preferred foci of attention different from the ones used in the studies, it is impossible to know for sure since the athletes were not asked. In the present study, the post-experimental questionnaire provides some insight into what the participants were actually paying attention.

Although participants in the current study reported following instructions and rated the instructions as highly effective, the qualitative comments by the participants indicate it is conceivable that participants blatantly disregarded the internal and external focus instructions and focused on something else entirely. For example, when asked to list which focus instruction was the most helpful, Participant 2 stated, “Being told 10 punches per round. I didn't even notice.” Additionally, Participant 3 responded to the same question with, “The one I found the most helpful was the description of time in between punches,” while Participants 7 and 11 responded with, “To follow the buzzer in each time to punch” and “1st directions should be punch through the bag as hard/fast.

(KO punch) and should be called ‘arm-punch,’" respectively. Finally, when asked to list which focus instruction they found to be most helpful, only five participants listed a focus condition, which all happened to be the external condition. Of the remaining eight participants, two listed “all instructions,” while the remaining six listed procedural particulars of the data collection that had which did not bear relevance with either an

28 internal or external focus instruction. It is possible that the instruction given to the participant was not received by the participants in the manner that was intended. Another possible explanation for the variety of responses could be that while participants were instructed to follow certain focus instruction, that does not guarantee that attempts to influence focus will always work (Post, Barros, & Wrisberg, 2011).

There are a number of limiting factors in this study. First off, a larger sample size could potentially make the interpretation of the statistical output more robust. The narrow requirements for participation, although necessary to control for confounding variables, made recruiting boxers difficult. The artificial nature of the data collection setting, which included the placement of sensor and wires around the participants’ body might have disrupted normal attentional focus patterns and interacted with the focus instructions provided in unexpected ways. And finally, although no differences in EMG activity in the pectoralis major and triceps brachii were observed, punching is a complex movement that requires synchronization of the lower and upper body. It is possible that the EMG activity in other muscle groups may indeed have been impacted by the instructions used, but were not captured using the current placement of the sensors. Future research projects investigatingthe impacts of internal and external focus instructions on EMG activity of complex movements should record EMG activity in other muscle groups such as the lower body.

In conclusion, although the results of the presented study were not expected based on the focus of attention literature, we were able to identify two important methodological concerns for future research in attentional focus. Based on the answers provided by the participants in this study, it is evident that determining if the participant

29 is going to use the intended focus before the data collection starts is extremely important.

This can be achieved by asking what the participant’s focus of attention will be right before the first trial of the task is completed. Another methodological recommendation is including EMG sensors in muscles that are more distant from the main action in studies that plan to investigate the constraint action hypothesis.

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APPENDIX A

INFORMED CONSENT

California State University FullertonResearch Study Consent Form

Study Title: The effect of internal and external focus conditions on punching impact force and EMG activity Researchers: Robert Mendoza, [email protected], Joao Barros, PhD, [email protected]. (657) 278 – 5986

You are being asked to take part in a research study carried out by Robert Mendoza, and Dr. Joao Barros.This consent form explains the research study and your part in it if you decide to join the study. Please read the form carefully, taking as much time as you need. Ask the researcher to explain anything you don’t understand. You can decide not to join the study. If you join the study, you can change your mind later or quit at any time. There will be no penalty or loss of services or benefits if you decide to not take part in the study or quit later.

What is this study about?

This research study is being conducted to examine the effects of attentional focus on punching impact force and muscle activity. You are being asked to take part because of your past experience in the sport of boxing. Taking part in this study will take approximately sixty minutes. To qualify for this study, you must be male, over the age of 18 and under the age of 40, have at least three years of boxing experience, and must have participated in vigorous boxing training at least twice a week for the past six months. You must also be free of any musculoskeletal injury and sensory or motor dysfunction.

What will I be asked to do if I am in this study?

If you take part in the study, the day of data collection you will first receive instructions and be given the chance to become familiar with the experimental equipment and task. The experimenter will answer any questions you have. You will first complete a self- selected warm up lasting ten minutes. Once you have completed the warm-up, you will be asked to put on the boxing gloves provided by the researcher. Once you have done so, you will be fitted with two EMG electrodes (sensors) on your dominant punching arm. Once you have the gloves and sensors fitted appropriately, you will have the opportunity to familiarize yourself with the equipment by performing 3 straight punches at 50% maximum effort on a modified (StrikeMate). This should take about 5

31 minutes. Following the familiarization punches, you will receive instruction, then perform10 maximal punches, with a 5 second rest in between each punch. This should take approximately a minute to complete. Following the tenth punch, you will be given a three minute rest period. At the completion of the threeminute rest period, you will be given additional instruction, then perform another 10 maximal punches. These ten punches should take approximately one minute. Once the second set of ten punches are complete, you will be given a post experimental questionnaire in which you will be asked to rate the instructions used in the experiment. You may refuse to answer any questions of the questionnaire. Immediately after data collection, participants will be given information of the expected results and have any questions answered by the researcher that are related to the study. Medical, academic or other sort of records will not be utilized in this study.

Are there any benefits to me if I am in this study?

The potential benefits to you for taking part in this study are: The opportunity to improve on your boxing skill, contribution to the motor learning literature by extending the findings of previous attentional focus studies as well as learning possible performance enhancement strategies.

Are there any risks to me if I am in this study?

The potential risks from taking part in this study include soreness of the arm, as well as wrist sprains. Knuckle bruising and soreness of the fingers from punching are also potential outcomes from participation of this study. If at any point you feel that you are unable to continue due to any sort of physical pain, discomfort or injury, you are free to stop what you are doing and remove yourself from participation if feel the need to do so.

Will my information be kept anonymous or confidential?

The data for this study will be kept confidential to the extent allowed by law. No published results will identify you, and your name will not be associated with the findings. Under certain circumstances, information that identifies you may be released for internal and external reviews of this project. Regarding your privacy, your information will be kept confidential. Only the experimenters will have access to information that can link you to your performance scores and the answers you give in the questionnaire. The data will be kept in a locked filing cabinet or, in case of digital data, in a password protected computer in the KHS building. Information linking your research ID and identifiers (i.e., your name, age, or contact information) will be kept separate from any data collected and stored in locked filing cabinets until the data collection is complete. After that, it will be destroyed. The data will be kept indefinitely for classes, research presentation and/or the publication of scientific articles but no information that can be used to identify you will made public. Confidentiality will be provided to the extent allowed by law.

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The results of this study may be published or presented at professional meetings, but the identities of all research participants will remain anonymous.

The data collected will be kept indefinitely. This data may be used in classes, academic/scientific presentations, and academic/scientific publications. No identifying information (identifiers) linking individual participants to the results will be presented.

Are there any costs or payments for being in this study?

No compensation will be provided to the participants other than the individual results of the study. Different participants have different preferences in terms of compensation. Thus, the participants' perception of the compensation might influence their engagement with the experimental task.

Who can I talk to if I have questions?

If you have questions about this study or the information in this form, please contact the researcher, Robert Mendoza, at [email protected]. If you have questions about your rights as a research participant, or would like to report a concern or complaint about this study, please contact the Institutional Review Board at (657) 278-7640, or e-mail [email protected]

What are my rights as a research study volunteer?

Your participation in this research study is completely voluntary. You may choose not to be a part of this study. There will be no penalty to you if you choose not to take part. You may choose not to answer specific questions or to stop participating at any time.

What does my signature on this consent form mean? Your signature on this form means that:  You understand the information given to you in this form  You have been able to ask the researcher questions and state any concerns  The researcher has responded to your questions and concerns  You believe you understand the research study and the potential benefits and risks that are involved.

Statement of Consent I have carefully read and/or I have had the terms used in this consent form and their significance explained to me. By signing below, I agree that I am at least 18 years of age and agree to participate in this project. You will be given a copy of this signed and dated consent form to keep.

Name of Participant (please print) ______

Signature of Participant Date ______

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Signature of Investigator Date______

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APPENDIX B

PUNCHING SCRIPT

Thank you for participating in this study. This task will require that you perform a total of twenty straight punches on the StrikeMate. Before you perform the punches, we need you complete a consent form followed by a fifteen minute, self-selected warm-up that you would normally complete during training and for competition.

Now that you have completed the warm, you will be fitted with electrodes on your punching arm and chest. Please put on the boxing gloves, and we will align you with the StrikeMate. Stand in front of the StrikeMate with your feet together and while making a fist, extend your preferred punching arm so that you are standing as far away from the

StrikeMate as possible without losing contact with your first. Once you have found the correct distance, adjust your foot placement and assume your boxing stance. We will then place tape so that you know where to stand for the second set of punches.

You will now have the opportunity to familiarize yourself to punch the

StrikeMate while wearing the electrodes. Using 50% of your perceived maximum power, you will perform three familiarization punches on the StrikeMate. You will be given fifteen seconds of rest in between these punches. Once you complete the familiarization punches, you will be given five minutes of rest, then we will begin our recorded punching trials. At the conclusion of the twenty recorded punches, the electrodes will be removed from your arm, and you will be given a questionnaire to complete. Once you complete

35 the questionnaire, you will be free to leave. Any questions? (Answer if necessary) Let’s begin the familiarization punches.

Familiarization Punches

You will perform a total of three familiarization punches. When you are ready, I will say “Go” which will be your queue to begin your first familiarization punch. Using a stopwatch, I will monitor time and wait fifteen seconds then say “GO,” which will be your queue to perform your second punch. Following your second punch, you will again wait fifteen seconds for my queue of “GO” and complete your last familiarization punch.

Any questions? (Answer if necessary) Following these three punches, you will rest for five minutes then begin the recorded punches.

Internal Condition

This series of punches will be recorded. I am going to give you an instruction that you will need to focus on during the entire set of punches. For every punch, try to produce the largest impact force. You will have five seconds of rest in between each punching trial. You will hear a buzzer sound, and once you do, that will be your queue to punch the bag. Do you have any questions? (Answer if necessary) Here is your instruction: “Focus on moving your arm as fast and as forcefully as you possibly can.”

When you are ready, I will start the program and you will punch each time you hear the buzzer. Do you have any questions? (Answer if necessary)

External Condition

This series of punches will be recorded. In every punch, try to produce the largest impact force.I am going to give you an instruction that you will need to focus on during the entire set of punches. You will have five seconds of rest in between each punching

36 trial. You will hear a buzzer sound, and once you do, that will be your queue to punch the bag. Do you have any questions? Here is your instruction: “Focus on punching the pad as fast and as forcefully as you possibly can.” When you are ready, I will say “Go”, which will be your queue to begin your first of ten trials. Do you have any questions?

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APPENDIX C

POST EXPERIMENTAL QUESTIONNAIRE

1. On a scale of one to four, rate the extent to which you followed the directions you were given.

1 2 3 4

Not at all Always

2. On a scale of one to four, how effective did you find the instructions to be?

1 2 3 4

Not at all Always

3. If you did not rate a “4” for either of the above questions, please state what you did in fact focus on during the punching trials.

4. Which focus instruction did you find to be most helpful?

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APPENDIX D

OPERATIONAL DEFINITIONS

Internal Focus: Focusing on one’s movements constitutes a conscious intervention into control processes that would “normally” regulate movements effectively and efficiently (Wulf 2007).

External Focus: Focus that is directed towards the movement effect on the environment (Wulf 2007).

Impact Force: Refers to the output produced by the StrikeMate punching pad.

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APPENDIX E

SPSS OUTPUT 1-RELATIVE IMPACT FORCE

Paired Samples Statistics Mean N Std. Deviation Std. Error Mean Pair 1 IntLAST7rel 172.4452597 13 49.08649669 13.61414467 ExtLAST7rel 192.1982545 13 74.19967432 20.57928695

Paired Samples Correlations N Correlation Sig. Pair 1 IntLAST7rel & ExtLAST7rel 13 .767 .002

Paired Samples Test Paired Differences Sig. 95% Confidence Interval (2- Std. Std. Error of the Difference tailed Mean Deviation Mean Lower Upper t df ) Pai IntLAST7rel - 48.2534038 13.3830862 - 9.4062453 - 1 .166 r 1 - 19.7529948 6 9 48.9122349 2 1.47 2 ExtLAST7r 0 2 6 el

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APPENDIX F

SPSS OUTPUT 2-RELATIVE IMPACT FORCE FOR FIRST AND SECOND SET OF PUNCHES

Paired Samples Statistics Mean N Std. Deviation Std. Error Mean Pair 1 firstSETrel 189.8170835 13 60.35557047 16.73962339 lastSETrel 174.8270578 13 66.04460110 18.31747659

Paired Samples Correlations N Correlation Sig. Pair 1 firstSETrel & lastSETrel 13 .690 .009

Paired Samples Test Paired Differences Sig. 95% Confidence Interval of (2- Std. Std. Error the Difference tailed Mean Deviation Mean Lower Upper t df ) Pai firstSETre 14.9900256 50.0760948 13.8886098 - 45.2507069 1.07 1 .302 r 1 l - 8 3 1 15.2706555 3 9 2 lastSETre 6 l

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APPENDIX G

SPSS OUTPUT 3-RELATIVE EMG RMS FOR PECTORALIS MAJOR

Paired Samples Statistics Mean N Std. Deviation Std. Error Mean Pair 1 IntPecM 4.2962113 13 6.34234521 1.75905007 ExtPecM 1.2359762 13 .30369929 .08423103

Paired Samples Correlations N Correlation Sig. Pair 1 IntPecM & ExtPecM 13 -.472 .103

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 IntPecM - 3.06023519 6.49129379 1.80036097 - 6.98288477 1.700 12 .115 1 ExtPecM .86241439

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APPENDIX H

SPSS OUTPUT 4-RELATIVE EMG RMS FOR TRICEPS BRACHII

Paired Samples Statistics Mean N Std. Deviation Std. Error Mean Pair 1 IntTriM 1.6482606 13 2.33639695 .64799992 ExtTriM 1.7293652 13 2.40532971 .66711843

Paired Samples Correlations N Correlation Sig. Pair 1 IntTriM & ExtTriM 13 .994 .000

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 IntTriM - - .26324006 .07300966 - .07796982 - 12 .288 1 ExtTriM .08110455 .24017893 1.111

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