Force Production Measurement Between Dominant and Non-Dominant Arm Using the Empty-Can and Full-Can Tests

Force Production Measurement between Dominant and Non-Dominant Arm using the Empty-can and Full-can Tests

A THESIS

Submitted to the Faculty of the School of Graduate Studies and Research of California University of Pennsylvania in partial fulfillment of the requirements for the degree of

Master of Science

by Timothy Richard Olsen

Research Adviser, Dr. Thomas Kinsey

California, Pennsylvania 2008 ii

CALIFORNIA UNIVERSITY OF PENNSYLVANIA CALIFORNIA, PA

THESIS APPROVAL

Graduate Athletic Training Education

We hereby approve the thesis of

Timothy Richard Olsen

Candidate for the degree of Master of Science

Date Faculty

Thomas Kinsey, PhD

Edwin Zuchelkowski, PhD

Michael Meyer, MS, ATC

iii

ACKNOWLEDGEMENTS

I would first like to thank God who was watched over me for the first 23 years of life and blessed me with all the riches in the world. Next I would like to thank my Mom, Dad, Pat, and Kristina. Mom, thanks for all the care packages through the years and the constant stream of never-ending love and affection. Dad, thanks for being a great role model and always there to lend me advice whenever I needed it and teaching me the value of hard-work. Pat, for all the years of constant psychological warfare I say thanks and “Mother of God”. Tina thanks for always being a wonderful little sister and sharing all those little talks. To both of you I hope the future brings everything you wish for and remember your older brother is always here for you, and never keep forgetting to thank Mom and Dad for all they have done for us. Next, I would like to thank Grandma and Grandpa for all they have done for me. From all the summer days at the shore, presents, meals, money, and love you have given me throughout my journey through life. I would also like to thank Boop and Pop who are no longer with us. Their memories have driven me to make them proud in what I do in life everyday and not a day goes by without a thought of how special they are to me. To all my extended family, those living and no longer with us, thanks for being so loving and a positive influence in my life. In a world full of negatives and broken homes, it has been great to brag about what a wonderful family I do have. Thanks to each and every one of you. Next, thanks to my friends Fran and Nick. You two have truly been great friends and I look forward to life-long friendships with both you guys. Words cannot say what the both of your friendships have meant to me through the years. Thanks for everything you both have done for me. For all those brothers from Lynchburg, the memories will last me a life time. Thanks. Next, I want to thank all the people who have helped me in my pursuit of being an Athletic Trainer. From Carl and Mr. Christy in high school to Dr. Laurent, Tom, Pat, Emily, and Debbie at Lynchburg College. Thanks to all of you for being great role models to look up to and teaching me about this wonderful profession of ours. Also, I would like to thank my thesis committee with whose approval I get to graduate with my Master of Science degree, Dr. Kinsey, Dr. Z, and Mike. Special thanks goes to Dr. Kinsey for being my thesis advisor and reading my thesis more times then he probably wanted to. My graduate class, the time has finally come to leave beautiful California and embark on the rest of our lives. It has been a great year together and there have been a lot of memories I will take with me. I am glad to have met all of you and wish you all nothing but the best. Chris, thanks for introducing me to 10 cent wing night at the Foster House, Pittsburgh style sandwiches, and an endless amount of humor. You definitely made this year a lot more fun then it probably should have been. In case I have forgotten anyone, sorry and thank you. For all those who read this in the future, always follow your dreams and do what will make you happy in life. iv

TABLE OF CONTENTS

Page

SIGNATURE PAGE ...... ii

ACKNOWLEDGEMENTS ...... iii

TABLE OF CONTENTS ...... iv

LIST OF TABLES ...... vii

LIST OF FIGURES ...... viii

INTRODUCTION ...... 1

METHODS ...... 6

Research Design...... 6

Subjects...... 7

Preliminary Research...... 7

Instruments ...... 8

Procedures ...... 9

Research Questions...... 11

Hypotheses ...... 11

Null Hypotheses ...... 12

Data Analysis ...... 12

RESULTS ...... 13

Demographics ...... 13 v

Hypotheses Testing ...... 15

Additional Findings ...... 17

DISCUSSION ...... 20

Discussion of Results ...... 20

Conclusions ...... 23

Recommendations ...... 24

REFERENCES ...... 26

APPENDICES ...... 29

A. Review of the Literature ...... 31

Functional Anatomy ...... 32

Bony Anatomy ...... 33

Joint Articulations ...... 35

Rotator Cuff Muscles ...... 38

Special Tests ...... 39

Dynamometer ...... 43

Effect of Dominance...... 44

Test Relevance ...... 45

B. The Problem ...... 47

Statement of the Problem ...... 48

Definition of Terms ...... 49

Basic Assumptions ...... 50

Limitations of the Study ...... 51

Delimitations of the Study ...... 52 vi

Significance of the Study ...... 52

C. Additional Methods ...... 54

Informed Consent Forms (Appendix C1)...... 56

Demographic Information Sheet (Appendix C2). . . . 62

Institutional Review Board (C3) ...... 64

REFERENCES ...... 73

ABSTRACT ...... 77

vii

List of Tables

Table 1. Frequency of Sport(s) Played and Percent Value

...... 14

Table 2. Average Force Production and Peak Times for Full-

can and Empty-can Test Positions ...... 15

Table 3. Subjects Force, Peak Time, and Age Ranges from

Table 4. Force Production 2x2 ANOVA Displaying Force

Production Between Tests is not Significant . . . . 16

Table 5. 2x2 ANOVA Displaying Peak Time Between Tests is

not Significant ...... 18

Table 6. Male Means...... 19

Table 7. Female Means ...... 19

viii

List of Figures

Figure 1. Demographic Information Sheet ...... 61

INTRODUCTION

The shoulder complex is an extremely complicated region of the body. Due to the anatomical structure of the passive restraints surrounding the glenohumeral (GH) joint, the shoulder has a great deal of mobility. This large range of motion makes the shoulder inherently unstable; therefore, the shoulder complex relies on the surrounding musculature for stability. The rotator cuff muscles are the primary dynamic stabilizers of the GH joint and are highly susceptible to injury. 1,2

Many sport activities such as throwing, swimming, serving in tennis or volleyball, etc., place a great deal of stress on the supporting structures of the GH joint.

Consequently, injuries involving the shoulder are commonplace in the athletic population. 2 Therefore it is important to have an extensive knowledge of shoulder anatomy as an athletic trainer. Rotator cuff muscles are a commonly injured muscle group in the shoulder. Injuries involving the rotator cuff typically involve the supraspinatus muscle, as it is the most commonly injured muscle in the rotator cuff group. 3-9 The diagnosis of a 2

rotator cuff injury is based on a history and physical examination. Two tests performed in determining the integrity of the supraspinatus muscle are the empty-can test and the full-can test.

However, rotator cuff injuries are not the only injuries that occur in the shoulder. Other injuries involving the shoulder include dislocations, subluxations, acromioclavicular sprains, sternoclavicular sprains, tendonitis, muscle weakness, fractures, instability, and impingement.

The complexity of the anatomy of the shoulder means an injury to any one of its structures can have an effect on the kinetic chain of the shoulder and the upper extremity.

For instance, a weak serratus anterior can cause the scapula to track incorrectly. Therefore, the surrounding musculature such as the rhomboids and rotator cuff muscles, have an increased workload due to the serratus anterior weakness. This can cause problems such as impingement or tendonitis in the shoulder due to the overload of work put on these muscles. Another example could be laxity in the shoulder joint and capsule. With increased mobility of the head of the humerus, the rotator cuff muscles have an increased role in stabilizing this joint and this increased workload may result in chronic injury. 3

Understanding the functional anatomy and associated

sources of injury of the shoulder allows the sports

medicine professional to have a more structured approach to

the care of an athletic shoulder injury. The diagnosis of a

rotator cuff injury is based on a history and physical

examination. Two tests performed in determining the

integrity of the supraspinatus muscle are the empty-can

test and the full-can test. 9 In a profession that relies heavily on tests being accurate in helping to determine pathologies, we need tests to be consistent as well.

Several studies have looked at the similarities and differences between the empty can and full can tests, and these studies have suggested that these tests have high sensitivity and low specificity. 5,10,11 Specificity means the degree to which a negative clinical test represents the absence of a condition. Sensitivity indicates the degree to which a positive test represents the presence of a condition.

The difference between the empty-can and full-can test is that the empty-can test is done with the athlete’s thumb facing downward perpendicular to the floor when pressure is applied downwards. The full-can test is performed with the athlete’s thumb pointing upward towards the sky, as if they 4

are giving a thumb’s up when pressure is applied. Other

than this, the tests are performed in the same manner.

Electromyography suggests that the supraspinatus

muscle is important during all phases of glenohumeral

motion as a humeral rotator and as a dynamic humeral

stabilizer. 12,13 Some authors have reported that there is

more pain with the empty-can test than with the full-can

test. 5,7,11 It has been reported that the optimal test for

the supraspinatus muscle is the full-can position, based on

an electromyography study. 11 However, Townsend et al. found increased muscle activation during the empty-can exercise and concluded that this position best isolated the supraspinatus. 14 Conversely, Malanga et al. saw no

difference in EMG or MRI supraspinatus activity between

full-can and empty-can positions. 15 This study suggests that

either test elicits an equal amount of supraspinatus

activity, making either test an appropriate method of

testing the integrity of the supraspinatus.

The results of several studies have suggested that the

volume of the supraspinatus outlet decreases during the

empty-can position. 16-19 Therefore if the supraspinatus

outlet through which the muscle runs is decreased in size,

it could theoretically cause more discomfort because the

muscle has less room in which to maneuver. However most of 5

the knowledge that we have today about the empty-can and full-can tests comes from research studies that use injured subjects to collect their data, as opposed to healthy subjects. Therefore, the design for this study is to use healthy subjects to collect data.

The purpose of this study will be to examine force production between the full-can position and empty-can position, to determine if a difference in force production exists. Secondly, this study will examine the force production in the dominant side versus the non-dominant side in the empty-can position or the full-can position, and determine which position and side is greater. The study will use a hand dynamometer to measure which position produces more force, and is anatomically a stronger position.

METHODS

This study looked at whether the full-can or empty-can position was a more accurate diagnostic test when assessing supraspinatus muscle integrity. This study focused its attention on the question: Is the force production in the full-can position greater or less than the empty-can position? This study determined if there was a 6

statistically significant difference between non-dominant and dominant arm force production from either test position. Also, will the force production be greater in the dominant side in the empty-can position or the full-can position? The following will be discussed: Research Design,

Subjects, Preliminary Research, Instruments, Procedures,

Hypotheses, and Data Analysis.

Research Design

A descriptive study using a pre-experimental one-shot design was used for this study. The dependent variables were the empty-can and full-can test positions, and the independent variables were arm dominance and the force production. A strength of this study was one tester administering the test, so no inter-tester reliability will need to be measured. The tester was aware that the objectivity, reliability, and sensitivity of the study could be affected either negatively or positively. However there is no way of measuring this factor and that was not a focus of this study.

Subjects

The subjects were minors from Frazier High School, a

Class A public school located in Perryopolis, Pennsylvania, who had all participated in at least one sport. Full IRB approval was obtained from the parents of the volunteers, and the volunteers themselves. Subjects that had self- reported pain in the past six months were excluded from this study. Athletes were not excluded from participation based upon which sport they participate in. Other information that was obtained is which arm the athlete considered to be the dominant arm and non-dominant arm, which was obtained after the subject had been tested. This was to keep the tester blind as to which arm is dominant and non-dominant and eliminate any bias. Dominance was defined by the following definition as the athletes had read to them: Which arm do you feel more comfortable performing sport specific activities?

Preliminary Research

The purpose of preliminary research was to familiarize the researcher with the instrument that was being used.

This was a practice trial to familiarize the tester with 8

the hand dynamometers and ensure they were being properly

used to gather data. Preliminary subjects included several

graduate students from the graduate athletic training

program at California University of Pennsylvania. This

preliminary research was simply used to know the settings

the dynamometers had and to correctly read the monitors

after testing the subjects.

Instruments

This study used a hand dynamometer from Lafayette

Instruments, Manual Muscle Tester Model 01163 made in 2008.

A dynamometer is an instrument which measures maximal forces produced that are generated by a particular maneuver. The dynamometer is used to measure force production from a variety of positions, depending on the needs of the assessment. Most dynamometers measure force in either pounds or newtons. 18 Studies have found that handheld dynamometers are the most reliable method of measuring rotator cuff strength, with excellent inter-rater reliability (0.79-0.92) and intra-rater reliability (0.70-

0.96) when testing shoulder strength. 5,18,31,32 The hand dynamometer will be placed on the lateral surface of the arm, just proximal to the elbow joint. 9

Procedures

Before testing began, coaches at Frazier High School were asked if their athletes could be used for this study. The study and consent forms underwent IRB review and approval before any actual data collection occurred (Appendix C3).

After a meeting with the athletes, all those interested in participating were given an assent form that included a consent form for their parents as well. Also with the consent forms, there was a letter addressed to the parents explaining the study and its procedures (Appendix C1). Upon receiving both signed consent forms from parents/guardians and athletes, testing procedures began. The testing procedures were explained to each subject one time before official measurements were taken.

The time each test position was to be evaluated for, was based on a preliminary survey of various certified athletic trainers asking them how long they make their athletes hold these test positions. All certified athletic trainers replied 2 seconds as the maximum time. Based on this survey each subject was evaluated in each test position for 2 seconds. 10

Subjects were randomly assigned which test they took first based on their subject number, which was determined by the order they came in for their test taking. All even numbered subjects performed the full-can test first, and all odd numbered subjects performed the empty-can test first. The hand dynamometers were strapped on the palmar surface on the tester’s hand and were placed on the lateral surface of the subjects’ arms just proximal to the elbow joint. All subjects were instructed to hold each test position for two seconds, one time for each test position.

Subjects were only tested one time in each position in order to make this study a more clinically accurate model of what would happen in a “real life” assessment. These tests did not stress the athletes anymore than their normal sport activities.

After each subject was done with the assessment, their maximal peak force production results were recorded along with demographic information on a subject sheet generated on Microsoft Excel. The information collected after testing included which arm was self-reported to be their dominant and non-dominant arm, based on the definition they were given, along with gender, age, and sport played. After all available subjects had been tested the data was entered into a spreadsheet in preparation for statistical analysis. 11

Research Questions

1. Will the force production in the full-can position be

greater than in the empty-can position?

2. Will the force production in the empty-can position be

greater than in the full-can position?

3. Will the force production be greater in the dominant

side in the empty-can position or the full-can

position?

4. Will there be an interaction between force produced in

dominant and non-dominant arm with full-can and empty-

can test position?

Hypotheses

1. The force production will be greater in the full-

can position versus the empty-can position.

2. The force production will be greater in the

dominant side versus non-dominant side for both the

full-can and empty-can test positions.

3. The force production will be the greatest in the

full-can position on the dominant arm. 12

4. There will be an interaction between force produced

in the dominant and non-dominant arm in the full-

can and empty-can test position.

Null Hypotheses

The amount of force produced in the empty-can and full-can test position will be the same.

The amount of force production between the non- dominant and dominant arm in either test position will be the same.

The force production will be the same in full-can versus empty-can position regardless of arm dominance.

There will be no interaction between force produced in dominant and non-dominant arm with full-can and empty-can test position.

Data Analysis

The hypotheses were tested using a 2x2 ANOVA.

Differences between test position, dominance, and their interaction were examined. The level of significance < .05 13

and SPSS version 14 was utilized to statistically analyze the data collected.

RESULTS

Demographics

For this study 40 athletes from Frazier High School

(30 male, 10 female), were tested. None of the subjects had reported shoulder pain in the last six months that prevented them from participating in the study. All but one athlete self-reported that they were right hand dominant.

Table 1 illustrates the sport(s) participated in by the subjects and percent breakdown each sport accounted for.

Table 1. Frequency of Sport(s) played and Percent value

Sport(s) Played Frequency Percent

Football 3 7.5

Baseball 7 17.5

Basketball 1 2.5

Softball 3 7.5

Football and Baseball 3 7.5

Football and Basketball 5 12.5

Football and Track and Field 4 10.0

Baseball and Basketball 4 10.0

Basketball and Softball 1 2.5

Volleyball and Basketball 1 2.5

Softball and Volleyball 3 7.5

Softball and Track and Field 1 2.5

Basketball, Baseball, Football 3 7.5

Volleyball, Softball, 1 2.5 Basketball

Total 40 100%

The force production ranged from 5.5 to 13.9 pounds of force as measure by the dynamometer, with a mean of 8.29 pounds. Table 2 represents the average force production in the Full-can (F.C.) and Empty-can (E.C.) test positions in the dominant (D) and non-dominant (N.D.) arm. These numbers were recorded in pounds. Also the average peak time for 15

each test position and dominant position was recorded in seconds and is also shown in Table 2.

Table 2. Average Force Production and Peak Times for Full-can and Empty-can Test Positions

Test Position Force Production Peak Time (lbs) (seconds) Full-Can (Dominant) 8.28 1.80 Full-Can (Non-Dominant) 8.34 1.74 Empty-Can (Dominant) 8.29 1.85 Empty-Can (Non-Dominant) 8.27 1.82

Table 3 represents the minimum, maximum, mean, and standard deviation for force production, time, and age of subjects.

Table 3. Subjects Force, Peak Time, and Age Ranges from Data collection

N Minimum Maximum Mean Std. Deviation

Force 160 1 5.5 13.9 8.30 1.974

Time 160 1 .66 1.90 1.803 .2573

Age 40 14 18 16.1 1.16

1Each subject had four observations done when being tested. F.C dominant and non-dominant, and E.C. dominant and non-dominant.

Hypothesis Testing

Four hypotheses were tested, and all hypotheses were tested using an alpha level of < .05. Table 4 represents the analysis of force production between the full-can and empty-can tests, displaying both dominant and 16

non-dominant results using the 2x2 ANOVA. The data displays

that the findings were not statistically significant as it

relates to the four hypotheses of this study. All 4 null

hypotheses were accepted in this study.

Table 4. Force Production 2x2 ANOVA displaying force production

between tests is not significant

Source Sum of Squares Df Mean Square F Sig.

Dominant .025 1 .025 .006 .937

Test .020 1 .020 .005 .943

Dominant * Test .064 1 .064 .016 .899

Error 616.849 156 3.954

Hypothesis 1: The force production will be greater in

the full-can position versus the empty-can position. It was

determined that force production was not statistically

significant in the full-can position versus the empty-can

position, and therefore the null hypothesis was accepted.

(Table 4)

Hypothesis 2: The force production will be greater in

the dominant side versus non-dominant side for both the

full-can and empty-can test positions. It was determined

that the force production was not statistically significant

in the dominant side versus the non-dominant side, and

therefore the null hypothesis was accepted. (Table 4) 17

Hypothesis 3: The force production will be the greatest in the full-can position on the dominant arm. It was determined that force production was not statistically significant in the full-can position versus the empty-can position regardless of arm dominance, and therefore the null hypothesis was accepted. (Table 4)

Hypothesis 4: There will be an interaction between force produced in the dominant and non-dominant arm in the full-can and empty-can test position. It was determined that the interaction was not statistically significant in the dominant and non-dominant arm in either the full-can or the empty-can position and therefore the null hypothesis was accepted. (Table 4)

Additional Findings

In addition to the hypotheses testing the researcher also examined the relationship between peak time of muscle contraction and whether it differed between each test. A

2x2 ANOVA was used to analyze the relationship of peak time of muscle contraction between the two tests. Table 5 illustrates that the peak time of muscle contraction 18

between the full-can and empty-can test was not statistically significant.

Also dominant arm was examined to determine if the dominant arm produced more force than the non-dominant arm.

After analyzing the 2x2 ANOVA it was determined that the dominant force production was not statistically significant compared to the force production of the non-dominant arm.

(Table 5)

The researcher examined whether or not an interaction existed between the full-can and empty-can tests. After analyzing the 2x2 ANOVA it was determined that there was not a statistically significant interaction between the two tests.

Table 5. 2x2 ANOVA displaying peak time between tests is not

significant

Sum of

Source Squares df Mean Square F Sig.

Dominant .089 1 .089 1.362 .245

Test .154 1 .154 2.345 .128

Dominant * Test .017 1 .017 .256 .613

Error 10.227 156 .066

Even though gender was not a concern of this study,

the researcher thought it would be of interest to compare

the means of the male and female subjects. Table 6

represents the male means and Table 7 represents the female

means for this study.

Table 6. Male means Test Position Force Production Peak Time (lbs) (seconds) Full-Can (Dominant) 8.9 1.81 Full-Can (Non-Dominant) 8.95 1.78 Empty-Can (Dominant) 8.94 1.83 Empty-Can (Non-Dominant) 8.85 1.79

Table 7. Female means Test Position Force Production Peak Time (lbs) (seconds) Full-Can (Dominant) 6.40 1.79 Full-Can (Non-Dominant) 6.52 1.60 Empty-Can (Dominant) 6.34 1.89 Empty-Can (Non-Dominant) 6.56 1.87

As indicated in the above tables, the males had roughly a 2 pound higher mean for force production in both test positions as well as dominant and non-dominant arm.

The peak time varied between each, with the females reaching a peak time faster in the full-can test, and the males reaching peak time faster in the empty-can test.

DISCUSSION

The discussion section of this study will be divided

into 3 sections: (1) Discussion of Results, (2)Conclusions,

and (3) Recommendations.

Discussion of Results

The diagnosis of a rotator cuff injury is based

on a history and physical examination. The two gold-

standard tests performed in determining the integrity of

the supraspinatus muscle are the empty-can test and the

full-can test. 9 Upon investigation of measuring force production between the empty-can and full-can tests using dominant and non-dominant arm it was determined that there was no significant difference between force production measurements between either test. It was also determined that no significant differences existed between peak time contraction of either test, regardless of dominance. Also no statistically significant interaction existed between dominant and non-dominant arm in either test position. This study used healthy subjects to gather data as many of the 21

previous studies dealing with these tests have used injured subjects.

Even though there were no statistically significant findings and all the null hypotheses were accepted, this study is relevant to the athletic training profession. By finding nothing significant this study demonstrates that the athletic training profession is doing the right thing by using both the full-can and empty-can tests in conjuction to evaluate the integrity of the supraspinatus muscle. This study reinforces the current research that both tests should be performed when evaluating an athlete and the athletic trainer should not favor one test over the other. Using both tests will generate roughly the same force production, based on this study, in healthy athletes.

As demonstrated in this study, healthy subjects yield approximately the same force production in both test positions, regardless of arm dominance. This is important to realize to the athletic trainer, because when an athlete does not have equal force production in one or both test positions an injury could be present. It is very important to perform all tests the athletic trainer deems necessary, and take all the test results and make an educated interpretation of what the problem might be. 22

Part of what drove this research study into reality

was the debate that existed between researchers that

examined both the full-can and empty-can tests. It has been

reported that the optimal test for the supraspinatus muscle

is the full-can position, based on an electromyography

study. 11 However, Townsend et al. found increased muscle activation during the empty-can exercise and concluded that this position best isolated the supraspinatus. 14 Conversely,

Malanga et al. saw no difference in EMG or MRI supraspinatus activity between full-can and empty-can positions. 15

The other main contributing factor to this study was the fact that most research studies examined used injured subjects to gather data. This study wanted to simulate a

“real world” evaluation that an athletic trainer working clinically might have to deal with. The only difference is most athletic trainers will not have access to a hand dynamometer when performing these tests in the field. The present study suggests that either test elicits an almost equal amount of force, making either test an appropriate method of testing the integrity of the supraspinatus. When the athletic trainer is under a time constraint of a game situation, both tests should be used to evaluate the supraspinatus. Based on their findings, the athletic 23

trainer makes an educated decision on whether or not the

athlete can return to play.

With the research data that is currently available it

is hard to determine if the supraspinatus is truly the only

muscle activated. Many findings suggest that these two

tests yield the most supraspinatus activity, but it is not

the only muscle that is activated. 3, 7,8,15

Conclusions

The findings of this study suggest that there is no

statistically significant difference in force production

between the full-can and empty-can test positions. Based on

the structural anatomy of the supraspinatus the researcher

agrees that these two tests stress the integrity of this

muscle the greatest and agree with the current research

available that endorses the empty-can and full-can test as

the two appropriate tests. The researcher did hypothesize

there would be more force production from the full-can

position versus the empty-can position, because the full-

can is an easier and more comfortable position, in the

researcher’s opinion, than the empty-can position. Also,

research suggests that the volume of the supraspinatus

outlet decreases during the empty-can position. 16-19 With this decrease in the size of the outlet it could be more 24

painful for the supraspinatus to be activated, and therefore more painful to produce force. This suggestion through research also led the researcher to believe that the full-can position would produce more force than the empty-can position. Also, no significant difference existed between peak times of either test as well. All null hypotheses were accepted.

Recommendations

Recommendations for future studies would have 3-5 different athletic trainers test the same subjects using hand dynamometers and compare their results. This would help determine how closely or differently each athletic trainer evaluates the same athlete and could possibly lead to a guideline for how much force an athletic trainer should apply when performing these two tests.

Another future study suggestion would be having a blind study with one group of injured subjects and one group of non-injured subjects having their force production measurements taken. After taking all subjects measurements it could be tried and determined which athletes were injured based on force production values discrepancies from injured side to non-injured side. With this knowledge there could be guidelines developed as to how much discrepancy 25

between an injured and non-injured arm would be considered a positive test. Also the possibility of using a different age group of subjects, such as college or professional athletes, to compare results could be done as well.

A third recommendation would be to conduct a study using both full-can and empty-can tests and asking subjects which test is more comfortable. There have been studies suggesting that the empty-can test may be more pain provocative due to the supraspinatus outlet decreasing in size. 16-19 If this claim has substance to it, there should be a study asking athletes which test they feel more comfortable performing. Based on this study both tests yield equal force production regardless of dominance, so why not perform the test that is more comfortable for the athlete to be evaluated in. Along with this, gender should be included to see if a difference exists between the sexes.

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13. Pearl ML, Perry J, Torburn L, Gordon LH. An electromyographic analysis of the shoulder during cones and planes of arm motion. Clin Orthop Relat Res. 1992;284:116-127. 28

14. Townsend H, Jobe F, Pink M, Perry J. Electromyographic analysis of the glenohumeral muscles during a baseball rehabilitation program. Am J Sports Med. 1991;19:264- 272.

15. Malanga GA, Jenp Y-N, Growney ES, An KN. EMG Analysis of shoulder positioning in testing and strengthening the supraspinatus. Med Sci Sports Exerc. 1996;28:661- 664.

16. Roberts C, Davila J, Hushek S, Tillet E, Corrigan T. Magnetic resonance imaging analysis of the subacromial space in the impingement sign positions. J Shoulder Elbow Surg. 2002;11:595-599.

17. De Wilde L, Plasschaert F, Berghs B, Hoecke M, Verstraete K, Verdonk R. Quantified measurement of subacromial impingement. J Should Elbow Surg. 2003;12:349-349.

18. Graichen H, Bonel H, Stammberger T, Haubner M, Rohrer H, Engimeier K, Reiser M, Eckstein F. Three- dimensional analysis of the width of the subacromial space in healthy subjects and patients with impingement syndrome. Am J Roen. 1999;172:1081-1086.

19. Graichen H, Bonel H, Stammberger T, et al. Three- dimensional analysis of shoulder girdle and supraspinatus motion patterns in patients with impingement syndrome. J Orthop Res. 2001;19:1192-1198.

APPENDICES

APPENDIX A

Review of Literature

LITERATURE REVIEW

The shoulder is a common site for injuries to occur during sport participation. The most commonly injured rotator cuff muscle in the shoulder is the supraspinatus. 1-7

The supraspinatus plays an important role in stability and function of the shoulder due to its anatomical position.

Because of the importance of the supraspinatus to the function of the body, athletic trainers have methods of testing the integrity of this muscle.

The two “gold standards” of testing the supraspinatus muscle are the empty-can and full-can tests. 1-5, 8-12 These two tests are specifically designed to test the integrity of this muscle. There have been many research studies done that have analyzed both of these tests, using EMG fine wire electrodes to measure the activity of the supraspinatus during both these maneuvers, with mixed results . 1,4,7,12,13

However, few studies have looked at force production from these two positions, as well as the effect that dominance has on force production. The theory is that an athlete’s dominant arm will yield more force than the non-dominant arm based on more developed musculature from being utilized more often during daily and sport-related activities. 32

With this knowledge, certified athletic trainers may

be able to determine if dominance has an effect on which

position is more appropriate to test the supraspinatus

muscle. The design of these special tests is to isolate

the supraspinatus, so only the supraspinatus muscle

integrity is evaluated.

Therefore, the purpose of this review of literature

will be 1) to explain the functional anatomy of the

shoulder, 2) to explain each special test, 3) to describe

the function of a dynamometer, 4) to explain the effect of

dominance, and 5) to explain the relevance of performing

this test.

Functional Anatomy

The movements of the shoulder are part of a complex relationship among muscle forces, ligaments, and bony articulations. Static and dynamic stabilizers allow the shoulder the greatest range of motion (ROM) of any joint in the human body. However this ROM does not come without inherent risk. The bony articulation of the glenohumeral joint relies heavily on ligamentous and muscular stabilizers throughout its ROM. The supraspinatus, one of the rotator cuff muscles, is responsible for stability of 33

the shoulder, as well as assisting in ROM. If any of the

stabilizers are injured, the shoulder is at increased risk

for injury. 14 Shoulder injuries account for 8-20% of athletic injuries, and the most commonly injured rotator cuff muscle is the supraspinatus. 1-7

Bony Anatomy

The humerus is the largest and longest bone of the upper extremity, with its proximal portion consisting of the head, greater tubercle, bicipital groove, lesser tubercle, and proximal humeral shaft. The greater tubercle has three facets into which the tendons of the supraspinatus, infraspinatus, and teres minor insert. The facets provide a continual ring of insertion for the rotator cuff muscles. This continual ring is interrupted by the bicipital groove, through which the long head of the biceps brachii passes. 14

The scapula is a large, thin, triangular bone lying on

the posterolateral side of the thorax, overlying ribs 2-7,

that serves as an area for muscle attachment. The superior

process or spine of the scapula, separates the

supraspinatus muscle from the infraspinatus and extends

superiorly and laterally to form the base of the acromion. 34

The spine of the scapula functions as part of the insertion of the trapezius muscle, as well as the origin of the posterior deltoid muscle. The supraspinatus fossa of the scapula also serves as the origin of the supraspinatus muscle. The acromion serves as a lever arm for function of the deltoid and articulates with the distal end of the clavicle, forming the acromioclavicular joint. The acromion forms a portion of the roof of the space for the rotator cuff muscles, and variations in acromial shape can affect contact and wear on the rotator cuff muscles. 14

The coracoid process projects anteriorly and laterally from the upper border of the head of the scapula. The tip of the coracoid process is the origin of the coracobrachialis muscle and the short head of the biceps brachii, and is also the insertion of the pectoralis minor muscle. The scapular notch lies just medial to the base of the coracoid and is spanned by the transverse scapular ligament. The suprascapular nerve passes beneath the ligament to innervate the supraspinatus and infraspinatus muscles. If this nerve is in any way impinged or has some type of injury or damage to it, the proper function of the supraspinatus and infraspinatus are at risk. 14

The clavicle serves as the only bony strut connecting the trunk to the shoulder girdle via the sternoclavicular 35

joint medially and the acromioclavicular joint laterally.

The clavicle has a double curve along its long axis and is

subcutaneous in its full extent. The flat outer third

serves as an attachment point for muscles and ligaments,

whereas the tubular medial third accepts axial loading. The

clavicle serves as a site for muscle attachments, a barrier

to protect underlying neurovascular structures, like the

suprascapular nerve, and a strut to stabilize the shoulder

complex and prevent it from displacing medially with

activation of the pectoralis and other axio-humeral

muscles. 14

Joint Articulations

The glenohumeral joint is designed for tremendous

mobility with its large humeral head and small articulating

surface. At any given time, only 25-30% of the humeral head

is in contact with the glenoid fossa. 14 With this low percentage of contact it is very important for the surrounding musculature, such as the supraspinatus, to be working efficiently to ensure the humeral head does not slip out of the glenoid fossa.

The acromioclavicular (AC) joint is a diarthrodial joint between the lateral border of the clavicle and the 36

medial edge of the acromion, and is covered by the joint

capsule. Stability of the AC joint is provided mainly

through the static stabilizers composed of the capsule,

intra-articular disc, and ligaments. 14

The scapulothoracic articulation is a space between the surface of the posterior thoracic cage and the concave surface of the anterior scapula. It is occupied by neurovascular, muscular, and bursal structures that allow smooth motion of the scapula on the thorax. The scapulothoracic articulation allows increased shoulder movement beyond the 120 o offered by the glenohumeral joint.

Seventeen muscles attach to or originate from the scapula

and function to stabilize the scapula and provide motion. 14

If there is a dysfunction in this articulation it can cause

a dyskinesis in shoulder movement. It can lead to muscles

placing extra tension on it that is above the normal

tension. 14 For example, the supraspinatus is one of the

muscles that originate on the scapula and a dyskinesis

involving the scapulothoracic articulation could place

greater stress on the supraspinatus. Greater stress placed

on the supraspinatus muscle predisposes it to having to

work more than it was designed for and can lead to injury

pathology. 37

Other scapulothoracic muscles include the trapezius, which functions primarily as a scapular retractor and elevator. The rhomboid, which has both a minor and major muscle, inserts on the medial border of the scapula and retracts as well as elevates the scapula. The levator scapula, as the name tells, is a synergist in elevating the scapula. It originates on the transverse processes of the cervical spine and inserts on the superior angle of the scapula. The serratus anterior takes its origin from the first nine ribs and inserts from the superior to inferior angle of the scapula. The serratus anterior causes scapular protraction and upward rotation, as well as a stabilizer for the scapula. The pectoralis minor muscle originates from the anterior 2 nd through 5 th ribs and inserts on the coracoid process. It is responsible for protraction and rotation of the scapula inferiorly. Finally, the deltoid muscle has three portions: an anterior portion, which originates from the lateral clavicle, a middle portion originating from the acromion, and a posterior portion originating from the spinous process of the scapula. All three portions insert distally at the deltoid tuberosity.

The anterior and middle portion allows for elevation and assists in forward flexion of the humerus. 14

Rotator Cuff muscles

The rotator cuff is an intricate network of tendons and other soft connective tissues that positions and stabilizes the glenohumeral joint. 15 The group of muscles that make up the rotator cuff consist of the subscapularis, supraspinatus, infraspinatus, and teres minor. As a group, the rotator cuff muscles are responsible for “steering” during shoulder motion, as well as stability. For a better understanding of each muscle, each will be described separately. 14

First, the supraspinatus muscle originates from the supraspinous fossa to insert at the superior aspect of the greater tubercle of the humerus. The supraspinatus stabilizes the glenohumeral joint and acts as a synergist in abduction of the humerus. Secondly, the infraspinatus originates from the infraspinatus fossa and extends laterally to insert on the middle of the greater tubercle.

The infraspinatus along with the teres minor are the primary external rotators as well as stabilizing the glenohumeral joint against posterior subluxation. Third, the teres minor originates from the axillary border of the scapula and inserts on the greater tubercle of the humerus.

Finally, the subscapularis originates from the subscapular 39

fossa and extends laterally to its insertion on the lesser

tubercle of the humerus. Its primary function is internal

rotation of the humerus. 14, 16

It is especially important when discussing the shoulder to think about the kinetic chain. One breakdown in the chain can cause a great deal of problems if not diagnosed and treated correctly. The shoulder is, as stated before, a very difficult and multifaceted joint of the body. It takes many hours of study and clinical experience to handle the complex nature of this area of the body.

Special Tests

Manual muscle testing is a vital component of the athletic training profession. 12 Manual muscle testing helps

athletic trainers make important decisions involving an

athlete’s return to play, rehabilitation program, or

stretching routine. These tests are one of the factors in

helping to diagnose injury pathology in an athlete. 12

Another group of tests that aid the athletic trainer in

evaluating an injury are what the profession calls special

tests.

A special test is designed to specifically test a

structure of the body. Two of the special tests that 40

involve the shoulder are called the empty-can test and full-can test. 1-5, 8-12 These two tests are designed to test the integrity of the supraspinatus muscle. Authors have described multiple ways in which to perform each of these tests, which has led to confusion on how to perform each test. 1,5,10,12,17,18 Kim et al. in their study describes the empty-can test with subjects arms abducted at 90 degrees horizontally and rotated 45 degrees internally, and the full-can test was done with subjects’ arms at 90 degrees horizontally abducted and 45 degrees of external rotation. 1

Another study describes the full-can test in 90 degrees of scaption and 45 degrees of external rotation. 12 Still another study describes the tests differently stating that the empty-can test is done with the arms at 90 degrees of abduction, internal rotation and the arm is then angled at

30 degrees forward. 19 This section will describe the most accepted way to administer both the empty-can and full-can tests.

The empty-can test, also known as the Jobe maneuver or supraspinatus test, is performed by having the examiner stand facing the patient. The examiner should have the patient place both arms in 90 0 of abduction and 30 0 of horizontal adduction in the plane of the scapula. The patient’s thumbs should be pointing downward in order to 41

produce internal rotation of the humerus. Then the

examiner pushes down on the patients’ arms while asking the

patient to resist the pressure. 18 The full-can test is done almost in the identical manner, except the patient’s thumbs are pointing up while the examiner is pushing down and the patient is resisting the pressure being applied. 18

These two tests are considered the “gold standard” to isolate and test the supraspinatus muscle. However, there have been conflicting studies involving both these tests.

There have been studies that have suggested, based on electromyography (EMG) analysis, increased supraspinatus activation in the empty-can position. 4,7,13,20 Conversely, studies have also found, based on EMG analysis, no difference in supraspinatus activity between the empty-can and full-can positions. 4,11 However there have been studies

that have found that the full-can position is less pain

provocative than the empty-can position. 5,13,21,22 Studies

have found increased anterior tipping of the scapula in the

empty-can position, when compared to the full-can

position. 4,23,24 This anterior tipping causes pain in healthy

rotator cuffs, because it closely resembles the position of

impingement syndrome. 22

Changes in scapular position have been shown to decrease the size of the subacromial space and therefore 42

the supraspinatus outlet is compromised. One of the muscles that travels through this outlet is the supraspinatus muscle, and with this outlet compromised the space for the supraspinatus is made smaller, and more pain provocative.4,

22,25 The empty-can position is believed to do this based on the mechanics of the test, as well as EMG, US, and MRI results. 6,11 Based on this knowledge, researchers and clinicians believe the full-can test is a better clinical assessment of the supraspinatus, since there is no compromise of the supraspinatus outlet. 7,12,13 Also the full- can test does not compromise the integrity of the supraspinatus outlet.

Studies published use EMG results to measure the activity of the supraspinatus in both test positions.

7,11,12,24 However, only a few studies use hand dynamometers to measure force output from either position. 2,26 However the majority of studies have used injured subjects to gather their data. 1,2,3,5,9,18,20-22,26-28 Furthermore, no studies have been found that compare the empty-can and full-can force production using a hand dynamometer on healthy subjects.

Dynamometer

A dynamometer is an instrument which measures maximal

forces produced that are generated by a particular

maneuver. You can use a dynamometer to measure force

production from a variety of positions, depending on what

needs to be assessed. Most dynamometers measure force in

either pounds or newtons. 26 There are handheld dynamometers, hydraulic gauge dynamometers, chassi dynamometers, etc. The two most commonly used types of dynamometers in the sports medicine profession are the handheld dynamometer and the hydraulic gauge dynamometer, which measures grip strength. 29

Studies have been conducted that use either handheld

dynamometers or hydraulic gauge dynamometers to measure

muscle strength. 26 Traditional shoulder strength assessment accomplished through manual muscle testing has produced varying results. 26 Dynamometers have been recently used in shoulder strength testing and were found to provide simple and reproducible results while still remaining noninvasive and inexpensive. Studies have found that handheld dynamometers are the most reliable method of measuring rotator cuff strength, with excellent inter-rater reliability (0.79-0.92) and intra-rater reliability (0.70-

0.96) when testing shoulder strength. 2, 26, 29, and 30

This study will use the hand dynamometer to measure supraspinatus strength from both the empty-can and full-can 44

positions. The dynamometer will be held on the subject’s

arm just proximal to the elbow, on the lateral side of the

upper arm.

Effect of Dominance

Muscle force can be graded in two ways. One is by varying the frequency of activation. If a motor unit is activated once, the muscle twitch that arises does not produce a lot of force. However, increasing the frequency of activation so that muscle twitches are allowed to summate results in greater force production by the motor unit, which means greater force production by that muscle.

This method of varying force output is generally used in smaller muscles in the body, such as the hand. 29 Force production of the whole muscle is intensified by increasing the frequency of firing of the individual motor units. This applies to this study, because the more times the supraspinatus musculature is activated, the stronger and more efficient the muscle contraction becomes. Therefore, if someone was right-hand dominant they would use their right arm more than their left, which would activate their right arm musculature more than their left, and would pre- dispose someone to having more developed muscles on their 45

right side. If this is the case, then one can see how

dominance can affect the force production from one’s

dominant side to their non-dominant side.

Test Relevance

The supraspinatus muscle is the most commonly injured rotator cuff muscle involved in a shoulder injury. 1-7 With

this being the case, the athletic training profession needs

a valid and reliable method of testing this structure. As

of now, the two most appropriate tests to evaluate the

supraspinatus are the empty-can test and full-can test. 1-5, 8-

12 However, reviewing the literature, neither test isolates

the supraspinatus better than the other. 4,11 Many studies

use injured subjects to collect their data, which

predisposes their subjects to have positive test results,

since there is already a supraspinatus pathology present. 1-

3,5,9,20-22,26-28 Also another aspect of these tests is the

effect that dominance has on the force production from

either arm. In theory an athlete’s dominant side should

yield more force production than the non-dominant side.

This study will use healthy subjects to gather data from

handheld dynamometer measurements from each test position

to determine force production. This study will try and 46

answer if the force production in the full-can position is less than the empty-can position or greater than empty-can position. Also, will the force production be greater in the dominant side in the empty-can position or the full-can position? The hypotheses are that the force production will be greater in the full-can position regardless of dominance, and the force production will be greater in the full-can position on the side of dominance.

APPENDIX B

The Problem

Statement of the Problem

The shoulder complex is an extremely complicated

region of the body. Due to the anatomical structure, the

shoulder has a great deal of mobility. With this large

range of motion the shoulder is inherently unstable, which

makes the shoulder complex rely on the surrounding

structures for stability and thus the shoulder is highly

susceptible to injury. 8,17 The diagnosis of a rotator cuff injury is based on a history and physical examination. Two tests performed in determining the integrity of the supraspinatus muscle are the empty-can test and full-can test. The purpose of this study is to answer if the force production in the full-can position is less than the empty- can position or greater than empty-can position. Also, will the force production be greater in the dominant side in the empty-can position or the full-can position?

Definition of Terms 49

The following terms have been defined for the purpose of this study:

1. Scaption – the word to describe the degree in the

scapular plane that combines abduction and horizontal

adduction of the arm.

2. Dyskinesis- a dysfunction that inhibits the normal

function of the kinetic chain.

3. Kinetic chain – refers to the anatomical relationships

that exist in the upper and lower extremities.

4. Empty-can test- The examiner should have the patient

place both arms in 90 0 of abduction and 30 0 of

horizontal adduction in the plane of the scapula. The

patient’s thumbs should be pointing downward in order

to produce internal rotation of the humerus. Then the

examiner pushes down on the patients’ arms while

asking the patient to resist the pressure.

5. Full-can test- The examiner should have the patient

place both arms in 90 0 of abduction and 30 0 of

horizontal adduction in the plane of the scapula. The

patient’s thumbs should be pointing towards the sky in

order to produce internal rotation of the humerus.

Then the examiner pushes down on the patients’ arms

while asking the patient to resist the pressure. 50

6. Dynamometer- A dynamometer is an instrument which

measures maximal forces produced that are generated by

a particular maneuver.

7. Force- the amount of energy, either in pounds or

newtons, generated from the subject that the handheld

dynamometer measures.

8. Dominance effect- the degree to which a subject uses

one arm more than the other, causing firing of the

motor units creating more muscle contractions for that

specific arm. This is turn could make the muscles

contract more efficiently since they are being used

more often, and cause more force production than the

non-dominant since the motor units are not being

contracted as often.

Basic Assumptions

The basic assumptions for this study are as follows:

1. The athletes will answer honestly when asked about

which arm they consider their dominant arm and non-

dominant arm.

2. The athletes will answer honestly when asked about

experiencing shoulder pain that affected their daily 51

activities in the past 6 months leading up the data

collection.

3. The athletes will give their maximal effort when being

tested.

4. The athletes will not perform a shoulder workout the

day before being tested.

5. The researcher will not show any bias during this

study.

Limitations of the Study

Some limitations of this study include:

1. A sample of convenience on high school athletes.

2. Sample size from the selected population.

3. The high school did not offer as many sports as other

surrounding high schools in the area.

4. There were 40 observations done in this study.

5. Not all athletes in the school returned their IRB

assent and/or consent forms.

Delimitations of the Study

1. Only athletes participated in this study.

2. Athletes that had no self-reported shoulder pain in

the previous 6 months leading up to this study.

3. Athletes from Frazier High School were used.

4. The study used an isometric contraction to measure

force production values.

5. The downward force applied by the researcher was done

for 2 seconds.

6. One researcher performed the testing of the subjects.

Significance of the Study

The shoulder complex is an extremely complicated region of the body. Due to the anatomical structure, the shoulder has a great deal of mobility. With this large range of motion the shoulder is inherently unstable, which makes the shoulder complex rely on the surrounding structures for stability and thus the shoulder is highly susceptible to injury. 17,31 Many sport activities such as throwing, swimming, serving in tennis or volleyball, place a great deal of stress on the supporting structures of the shoulder. Consequently, injuries involving the shoulder are commonplace in the athletic population. 31 Therefore it is important to have an extensive knowledge of the shoulder 53

anatomy as an athletic trainer. Injuries involving the

rotator cuff typically involve the supraspinatus muscle, as

it is the most commonly injured muscle in rotator cuff

injuries. 1-7 The diagnosis of a rotator cuff injury is based on a history and physical examination. Two tests performed in determining the integrity of the supraspinatus muscle are the empty-can test and full-can test.

Also another aspect of these tests is the effect that

dominance has on the force production from either arm. In

theory an athlete’s dominant side should yield more force

production than the non-dominant side. This study will use

healthy subjects to gather data from handheld dynamometer

measurements from each test position to determine force

production. This study will try and answer if the force

production in the full-can position is less than the empty-

can position or greater than empty-can position. Also, will

the force production be greater in the dominant side in the

empty-can position or the full-can position? These answers

would help the athletic training professional better

interpret the results they receive when they use these two

tests to assess supraspinatus integrity in the practical

settings.

APPENDIX C

Additional Methods

APPENDIX C1

Informed Consent

Subject Informed Assent Form

1. Timothy Olsen, who is the Graduate Assistant Athletic Training Student assigned to Frazier High School, has requested my participation in a research study at the High School. The title of this research is Force Production Measurement between Non-dominant and Dominant arm using the Empty-Can and Full-Can tests.

2. I have been informed that the purpose of this research is to determine whether or not a difference exists in the force production between the Empty-can and Full-can test positions, and also if there is a difference in force production between non- dominant and dominant arms. The study will take place over a couple of weeks with each subject being tested once. During the testing period the athletes will not have to perform anything that will stress them more than their sport. The empty-can test, also known as the Jobe maneuver or supraspinatus test, is performed by having the examiner stand facing the patient. The examiner should have the patient place both arms in 90 0 of abduction and 30 0 of horizontal adduction in the plane of the scapula. The patient’s thumbs should be pointing downward in order to produce internal rotation of the humerus, like they are holding an empty-can of tennis balls at shoulder height. Then the examiner pushes down on the patients’ arms while asking the patient to resist the pressure. The full-can test is done almost in the identical manner, except the patient’s thumbs are pointing up, like they are holding up a full-can of tennis balls at shoulder height, while the examiner is pushing down and the patient is resisting the pressure being applied. Once again these tests will not stress the athletes beyond their regular stresses incurred by their sport. These two tests are considered the “gold standard” to isolate and test the supraspinatus muscle.

3. My participation will involve one day of being tested once in the Empty-can and Full-can test positions.

4. There are no foreseeable risks or discomforts that may occur to you in this study.

5. I understand that in case of injury I can expect to receive treatment and/or care in the Athletic Training Room in Frazier High School which will be provided by the Graduate Assistant Athletic Training Student assigned to Frazier High School, Timothy Olsen who can administer emergency and rehabilitative care. Additional services needed for prolonged care past 3 days will be referred to my family physician or orthopedic doctor.

6. There are no feasible alternatives procedures available for this study. 57

7. I understand that the results of the research study may be published, however the results and my name or identity are confidential and will not be revealed. In order to maintain confidentiality of my records, Timothy Olsen will not release any information concerning my identity. This includes measurements, personal history or any personal information.

8. I have been advised that the research in which my participation is being requested does not involve more than minimal risk, and you will not be stressed more than normal sport activity.

9. I have been informed that I will not be compensated for my participation.

10. I have been informed that any question I have concerning the research study or my participation in it, before or after consent, will be answered by Timothy Olsen, [email protected], 947 Cross Street, Apt. 1 California, PA 15419, (609) 707-1670 and Dr. Thomas Kinsey, [email protected], 250 University Ave. California, PA 15419, (724-938-6033)

11. I understand that written responses may be used in quotations for publication but my identity will remain anonymous.

12. I have read the above information. The nature, demands, risks, and benefits of the project have been explained to me. I knowingly assume the risks involved, and understand that I may withdraw my consent and discontinue participation at any time without penalty or loss of benefit to myself. In signing this consent form, I am not waiving any legal claims, rights, or remedies. A copy of this consent form will be given to me upon request. Students Signature______Date______

13. I certify that I have explained to the above individual the nature and purpose, the potential benefits, and possible risks associated with participation in this research study, have answered any questions that have been raised, and have witnessed the above signature.

14. I have provided the subject/participant a copy of this signed consent document if requested. Investigators Signature______Date______

Date Approved: 2-18-2008 58

Expiration Date: 2-17-2009

Parent Informed Consent Form 1. Timothy Olsen, who is the Graduate Assistant Athletic Training Student assigned to Frazier High School, has requested my minor child’s participation in a research study at the High School. The title of this research is The Force Production Measurement between Non-dominant and Dominant arm using the Empty-Can and Full-Can tests.

3. My child’s participation will involve one day of being tested once in the Empty-can and Full-can test positions.

4. There are no foreseeable risks or discomforts that may occur to my child in this study.

5. I understand that in case of injury my child can expect to receive treatment or care in the Athletic Training Room in Frazier High School which will be provided by the Graduate Assistant Athletic Training Student assigned to Frazier High School, Timothy Olsen can administer emergency and rehabilitative care. Additional services needed for prolonged care past 3 days will be referred to my family physician or orthopedic doctor.

6. There are no feasible alternatives procedures available for this study.

7. I understand that the results of the research study may be published, however my child's name or identity will not be revealed. In order to maintain confidentiality of my child's records, Timothy Olsen will not release any information concerning my child. This includes measurements, child's history or any personal information.

8. I have been advised that the research in which my child's participation is being requested does not involve more stress than normal sport activity.

9. I have been informed that I will not be compensated for my child's participation.

10. I have been informed that any question I have concerning the research study or my participation in it, before or after consent, will be answered by Timothy Olsen, [email protected], 947 Cross Street Apt.1 California, PA 15419, (586) 709-0865 and Dr. Thomas Kinsey, [email protected], 250 University Ave. California, PA 15419, (724-938-6033)

11. I understand that written responses may be used in quotations for publication but my identity will remain anonymous.

14. I certify that I have explained to the above individual the nature and purpose, the potential benefits, and possible risks associated with participation in this research study, have answered any questions that have been raised, and have witnessed the above signature.

15. I have provided the subject/participant a copy of this signed consent document if requested. Investigators Signature______Date______60

Date Approved: 2-18-2008 Expiration Date: 2-17-2008

APPENDIX C2

Demographic Information Sheet

Figure 1. Demographic Information Sheet Subject Gender Age Sport(s) Dom. N.D. 1 M 17 fb,bb R L 2 M 16 fb,bb R L 3 M 16 fb,bb R L 4 M 15 fb,bb R L 5 M 15 fb,bb R L 6 M 17 bb.bkb.g R L 7 M 16 fb,tf R L 8 M 16 fb R L 9 M 17 bb, R L 10 M 16 bb, R L 11 M 16 fb, tf, R L 12 M 14 bb,bkb,fb R L 13 F 17 vb,sb, R L 14 M 18 fb,tf R L 15 F 16 sb,cc R L 16 M 15 bb,bkb,fb R L 17 M 17 fb, tf, R L 18 M 18 fb,bb R L 19 M 16 bb, R L 20 M 17 bb,fb R L 21 M 16 g,bb,bkb, R L 22 F 14 vb,bb R L 23 M 14 fb, bb, bkb R L 24 M 18 bb R L 25 M 15 bb, bkb R L 26 M 18 bb, R L 27 M 17 fb,bb R L 28 M 16 bb R L 29 M 17 bkb,bb R L 30 M 17 bb R L 31 F 16 sb, R L 32 F 15 bkb,sb R L 33 F 15 sb R L 34 F 15 vb,sb, R L 35 F 15 vb,sb, R L 36 F 18 sb L R 37 F 15 vb,sb,bkb R L 38 M 15 bkb R L 39 M 17 fb R L 40 M 17 fb R L

APPENDIX C3

Institutional Review Board

Please attach a typed, detailed summary of your project AND complete items 2 through 6. 1. Provide an overview of your project-proposal describing what you plan to do and how you will go about doing it. Include any hypothesis(ses)or research questions that might be involved and explain how the information you gather will be analyzed. For a complete list of what should be included in your summary, please refer to Appendix B of the IRB Policies and Procedures Manual.

Before testing begins, coaches at Frazier High School will be asked if their athletes can be used for this study.

The study and consent forms will have undergone IRB review before any actual data collection can occur. Based upon the cooperation from the coaches, the athletes will have the testing procedures explained to them at a team meeting.

After this meeting, athletes interested in participating will be given a consent form that includes a consent form for their parents as well. My contact information will be provided in the letter to the parents/guardians in case they have any questions prior to their children’s participation in the study. Also with these consent forms will be a letter addressed to the parents explaining the study and its procedures. Upon receiving signed consent forms from parents/guardians and athletes, the athletes name will be stored on the subject spread sheet, generated using Microsoft excel. After this is done data collection will begin. The testing procedures will be explained to 66

each subject one time before official measurements are taken.

The time to hold the position is based on the preliminary survey of various certified athletic trainers asking them how long they make their athletes hold these test positions. Subjects will be randomly assigned which test they take first based on their subject number, which will be determined by the order in which they turn in their consent forms. All even numbered subjects will perform the full-can test first, and all odd numbered subjects will perform the empty-can test first. The hand dynamometers will be strapped on the palmar surface on the tester’s hand and will be placed on the lateral surface of the subjects’ arms just proximal to the elbow joint. All subjects will be asked to hold each test position for one to two seconds, one time for each test position. Subjects will only be tested one time in each position in order to make this study a more clinically accurate model of what would happen in a “real life” assessment. These tests are not stressing the athletes anymore than their normal sport activities.

After each subject is done with the assessment, their maximal peak force production results will be recorded along with demographic information on a subject sheet generated on Microsoft Excel. The information collected 67

after testing will include which arm is self-reported to be

their dominant and non-dominant arm, based on the

definition they were given, gender, age, and sport played.

Arm dominance will be defined by the following definition

as the athletes will have read to them: Which arm do you

feel more comfortable performing sport specific activities?

After all available subjects have been tested, the data

will be entered into a spreadsheet in preparation for

statistical analysis.

This study will use a hand dynamometer from Lafayette

Instruments. A dynamometer is an instrument which measures

maximal forces produced that are generated by a particular

maneuver. You can use a dynamometer to measure force

production from a variety of positions, depending on the

needs of the assessment. Most dynamometers measure force in

either pounds or newtons. 18 Studies have found that handheld dynamometers are the most reliable method of measuring rotator cuff strength, with excellent inter-rater reliability (0.79-0.92) and intra-rater reliability (0.70-

0.96) when testing shoulder strength, as well as being noninvasive and simple to use with the subjects being tested.

The empty-can test, also known as the Jobe maneuver or supraspinatus test, is performed by having the examiner stand facing the patient. The examiner should have the 68

patient place both arms in 90 0 of abduction and 30 0 of horizontal adduction in the plane of the scapula. The patient’s thumbs should be pointing downward in order to produce internal rotation of the humerus, like they are holding an empty-can of tennis balls at shoulder height.

Then the examiner pushes down on the patients’ arms while asking the patient to resist the pressure. The full-can test is done almost in the identical manner, except the patient’s thumbs are pointing up, like they are holding up a full-can of tennis balls at shoulder height, while the examiner is pushing down and the patient is resisting the pressure being applied. Once again these tests will not stress the athletes beyond their regular stresses incurred by their sport. These two tests are considered the “gold standard” to isolate and test the supraspinatus muscle.

The hypotheses will be tested using a 2x2 ANOVA.

Differences between test position and dominance will be examined. The level of significance < .05 and SPSS version

14 will be used to statistically analyze the data collected.

The following are research questions regarding this study:

1. Will the force production in the full-can position be greater than in the empty-can position? 69

2. Will the force production in the empty-can position be greater than in the full-can position? 3. Will the force production be greater in the dominant side in the empty-can position or the full-can position? 4. Will there be an interaction between dominant and non- dominant arm with full-can and empty-can test position?

The following hypotheses will be tested:

1. The force production will be greater in the full-can position versus the empty-can position. 2. The force production will be greater in the dominant side versus non-dominant side for both the full-can and empty- can test positions. 3. The force production will be greater in full-can dominant arm position.

Also, if the need arises other area high schools will be contacted, if not enough subjects are gathered from Frazier High

School.

4. Section 46.11 of the Federal Regulations state that research proposals involving human subjects must satisfy certain requirements before the IRB can grant approval. You should describe in detail how the following requirements will be satisfied. Be sure to address each area separately.

a. How will you insure that any risks to subjects are minimized? If there are potential risks, describe what will be done to minimize these risks. If there are risks, describe why the risks to participants are reasonable in relation to the anticipated benefits.

All subjects will be informed of the risks involved as stated in the informed consent. All subjects will have up-to-date physicals, as required by the school, before participating. The risk of injury is minimal and is no greater than the risk associated with participation in their sport. The researcher is 70

certified in first aid and CPR, should care beyond this level of

skill be needed, the participant will be referred to their family

physician.

b. How will you insure that the selection of subjects is equitable? Take into account your purpose(s). Be sure you address research problems involving vulnerable populations such as children, prisoners, pregnant women, mentally disabled persons, and economically or educationally disadvantaged persons. If this is an in-class project describe how you will minimize the possibility that students will feel coerced.

All athletes at the high school will be allowed to participate with one exception. Athletes that have self-reported shoulder pain in the past 6 months will be excluded from the study. Shoulder pain will be defined as pain that has kept you from performing daily normal activities free of pain. No punishment of any kind will be given by either the researcher or the coach if they do not wish to participate or finish the study.

c. How will you obtain informed consent from each participant or the subject’s legally authorized representative and ensure that all consent forms are appropriately documented? Be sure to attach a copy of your consent form to the project summary.

Prior to the beginning of the study the researcher will

hold an informational meeting describing the study and showing

them what tests will be done. At this time the informed consent

and assent form will be distributed. Students will not be

permitted to participate without both forms being signed and

turned in.

d. Show that the research plan makes provisions to monitor the data collected to insure the safety of all subjects. This includes the privacy of subjects’ responses and provisions for maintaining the security and confidentiality of the data.

All information will be kept in a secure location at the residence of the researcher. Only the researcher will have access to the records, and if need be the research advisor will see them.

5. Check the appropriate box(es) that describe the subjects you plan to use.

Adult volunteers Mentally Disabled People CAL University Students Economically Disadvantaged People Other Students Educationally Disadvantaged People Prisoners Fetuses or fetal material Pregnant Women Children Under 18 Physically Handicapped People Neonates

6. Is remuneration involved in your project? Yes or No. If yes, Explain here.

7. Is this project part of a grant? Yes or No If yes, provide the following information: Title of the Grant Proposal ______Name of the Funding Agency Dates of the Project Period 8. Does your project involve the debriefing of those who participated? Yes or No If Yes, explain the debriefing process here.

If your project involves a questionnaire interview, ensure that it meets the requirements of Appendix __ in the Policies and Procedures Manual.

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ABSTRACT

TITLE : Force Production measurement between Dominant and Non-Dominant Arm using the Empty-can and Full-can Tests

RESEARCHER: Timothy Richard Olsen

ADVISOR: Dr. Thomas Kinsey

DATE: May 2008

RESEARCH TYPE: Masters Thesis

PURPOSE: The purpose of this study will be to examine force production between the full-can position and empty-can position, to determine if a difference in force production exists.

PROBLEM: Two tests performed by the certified athletic trainer in determining the integrity of the supraspinatus muscle are the empty-can test and full-can test. This study will answer if the force production in the full-can position is less than the empty-can position or greater than empty-can position.

METHODS: A descriptive study using a pre-experimental one-shot design was used for this study. All subjects had no self-reported shoulder pain the previous 6 months leading up to this study. A hand-held dynamometer was used to collect data on force production values.

FINDINGS: The force production was not significantly different between the full-can and empty-can tests.

CONCLUSIONS: Both tests equally stress the integrity of the supraspinatus muscle and both should be used in conjunction when evaluating an athlete.