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The effect of antecedent muscle tension levels on the performance of selected motor activities Shultz, Terry Donald 1977

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THE EFFECT OF ANTECEDENT MUSCLE TENSION LEVELS ON THE PERFORMANCE OF SELECTED MOTOR ACTIVITIES BY TERRY DONALD SCHULTZ B.P.E., U n i v e r s i t y of B r i t i s h Columbia, 1975 A t h e s i s submitted i n p a r t i a l f u l f i l l m e n t of the requirements f o r the degree of MASTER OF PHYSICAL EDUCATION i n THE FACULTY OF GRADUATE STUDIES Department of P h y s i c a l Education and Recreation We accept t h i s t h e s i s as conforming to the re q u i r e d standard J u l y , 1977 (£) Terry Donald S c h u l t z , 1977 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r a n advanced degree at the U n i v e r s i t y of B r i t i s h C o l u m b i a , I a g r e e t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e fo r r e f e r e n c e a n d s t u d y . I f u r t h e r agree tha t permiss ion for e x t e n s i v e copying o f t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head o f my D e p a r t m e n t o r by h i s r e p r e s e n t a t i v e s . It i s understood that c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l ga in s h a l l not b e a l lowed without my w r i t t e n p e r m i s s i o n . Department of Physical Education The U n i v e r s i t y of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1WS D a t e Auguat 2, 1977 ABSTRACT The general purpose of t h i s t h e s i s was to determine whether f u t u r e research i n v o l v i n g EMG biofeedback as a pre-competition muscle r e l a x a t i o n technique f o r competitive a t h l e t e s was warranted. More s p e c i f i c a l l y , the goals were f i r s t to determine i f there were increases i n the muscle ten-s i o n l e v e l s of competing a t h l e t e s p r i o r to competitive events and then to determine whether such increases could a f f e c t the performance of motor t a s k s . In Experiment 1 the muscle t e n s i o n l e v e l s of the r i g h t forearm f l e x o r and quadricep muscle groups of 10 c o l -l e g i a t e w r e s t l e r s were monitored p r i o r to a competitive event There was a s i g n i f i c a n t increase i n the l e v e l s of muscle ten-s i o n of the r i g h t forearm f l e x o r group. I n Experiment 2 subjects were asked to reproduce these increases i n muscle t e n s i o n w i t h the a i d of EMG biofeedback p r i o r to the perform-ance of three motor s k i l l s . I t was discovered that such i n -creases i n muscle t e n s i o n d i s r u p t e d the performance of both the Hand-Steadiness and Grip-Strength Tests. Thus, compet-i t i v e a t h l e t e s do have elevated pre-competition l e v e l s of muscle t e n s i o n which may d i s r u p t some kinds of motor perform-ance. The present r e s u l t s , t h e r e f o r e , suggest that f u t u r e re search i n v o l v i n g EMG biofeedback as a pre-competition muscle r e l a x a t i o n technique f o r competitive a t h l e t e s i s warranted. ACKNOWLEDGEMENTS The author i s indebted to Dr. J.P.J P i n e l whose keen s u p e r v i s i o n and c r i t i c a l p e r c e p t i o n was appreciated beyond words. The author a l s o wishes to thank Dr. R. Schutz, Mrs. S. B l e u l e r , Dr. G. S i n c l a i r and Mr. R. Laycoe f o r t h e i r numerous c o n t r i b u t i o n s . A s p e c i a l thanks i s extended to the many subjects who volunteered f o r t e s t i n g and surrendered countless l a y e r s of s k i n i n the process. i i i TABLE OF CONTENTS Page ABSTRACT . . i i ACKNOWLEDGEMENTS i i i LIST OF TABLES v i LIST OF FIGURES v i i Chapter 1. INTRODUCTION TO THE PROBLEM . . . . . . . . 1 I n t r o d u c t i o n 1 Statement of the Problem 1 Hypotheses . 2 D e f i n i t i o n of Terms 2 D e l i m i t a t i o n s 3 L i m i t a t i o n s 3 J u s t i f i c a t i o n of the Study h 2. REVIEW OF THE LITERATURE 5 S e c t i o n I : Physiology, Measurement, and Biofeedback. Control, of Muscle Tension . . . . . 5 S e c t i o n I I : The Relevance of the L i t e r a t u r e R e l a t i n g Muscle Tension and Performance 11 3. METHODS AND PROCEDURES 18 I n t r o d u c t i o n 18 Se c t i o n I:' Methods and Procedures of Experiment 1 18 Subjects - 18 Apparatus 18 Experimental Design 19 Procedures 19 S t a t i s t i c a l Analyses 20 Se c t i o n I I : Methods and Procedures of Experiment 2 ... ... ... ... . ... ... . ... ... . 21 Subjects 21 i v Experimental Design . . . . . 22 Procedures 23 Test 1: Hand-Steadiness Test . . . . . 26 Test 2: Choice Response-Time Test . . 27 Test 3: Grip-Strength. Test .. ... ... .. .. ... 29 S t a t i s t i c a l Analyses 30 il-. RESULTS AND DISCUSSION 31 Results of Experiment 1 31 D i s c u s s i o n of Experiment 1 35 Resu l t s of Experiment 2 39 Test 1: Hand-Steadiness Test 39 Test 2: Choice Response-Time Test . . 43 Test 3: Grip-Strength Test ... ... ... ... ... ... 4-3 D i s c u s s i o n of Experiment 2 5 0 General D i s c u s s i o n 52 Methodological Innovations 53 Muscle Tension and S u b j e c t i v e Tension . . 54 P h y s i o l o g i c a l Mechanisms 57 S t r a t e g i e s of A p p l i e d Research 58 5. SUMMARY AND CONCLUSIONS . . 62 REFERENCES 64 v LIST OF TABLES Table Page 1. E v a l u a t i o n of Nine Studies of the R e l a t i o n s h i p Between Muscle Tension and Performance with Respect to the App l i e d Goals of the Present Thesis . . . 13 2. L a t i n Square Design of Experiment 2 . . . . 22 3. EMG A c t i v i t y of the Forearm F l e x o r and Quadricep Muscles Recorded During the S i x T e s t i n g Sessions 34 4. ANOVA Table f o r the Forearm F l e x o r Muscle S i t e 36 5. ANOVA Table f o r the Quadricep Muscle S i t e 36 6. Means and Standard D e v i a t i o n s f o r the Two Measures of Hand Steadiness 42 7. P r o b a b i l i t y Values, for. the. Hand-Steadiness Test 42 8. Means and Standard D e v i a t i o n s f o r the Three Measures of Speed of Response . . . 46 9. P r o b a b i l i t y Values f o r the. Choice Response-Time Test 46 10. Means and Standard D e v i a t i o n s f o r the Two Measures of Grip-Strength 49 11. P r o b a b i l i t y Values f o r the Gr i p -Strength Test 49 v i LIST OF FIGURES Figure Page 1. Diagrammatic r e p r e s e n t a t i o n of the temporal sequence of events during each t e s t i n g s e s s i o n 25-2. P r e - p r a c t i c e and pre-competition l e v e l s of muscle t e n s i o n i n the forearm, f l e x o r .. .. and quadricep muscle groups 33 2>. R e l a t i o n between performance on the Hand-Steadiness Test and antecedent l e v e l s of muscle t e n s i o n . . . . . 4 l V 4 . R e l a t i o n between performance on the Choice Response-Time Test.and .antecedent levels.. of muscle t e n s i o n 4 5 5 . R e l a t i o n between performance on the G r i p -Strength Test and antecedent, l e v e l s of muscle t e n s i o n 4 8 v i i Chapter 1 INTRODUCTION TO THE PROBLEM I n t r o d u c t i o n The research reported i n t h i s t h e s i s was based on the premise that performance i n competitive sports may be r e l a t e d to the l e v e l s of muscle t e n s i o n i n the p e r i o d imme-d i a t e l y p r i o r to competition.' Although there i s general support i n the experimental l i t e r a t u r e f o r t h i s assumption of a r e l a t i o n between l e v e l s of muscle t e n s i o n and performance, only a few of the e x i s t i n g s t u d i e s are methodologically ade-quate and none i s d i r e c t l y r e l a t e d to the s p e c i f i c a p p l i e d goals of t h i s t h e s i s (see Chapter 2). The recent development of biofeedback procedures f o r t r a i n i n g s u bjects to c o n t r o l t h e i r l e v e l s of muscle tension r a i s e s the p o s s i b i l i t y that competitive a t h l e t e s could en-hance t h e i r performance by l e a r n i n g to c o n t r o l t h e i r l e v e l s of muscle t e n s i o n i n the p e r i o d p r i o r to competition. Statement of the Problem The general purpose of t h i s t h e s i s was to t e s t the f e a s i b i l i t y of using EMG biofeedback techniques to improve a t h l e t i c performance. Two experiments were conducted to t e s t the p o s s i b i l i t y of using t h i s technique. The purpose of the f i r s t experiment was to t e s t the hypothesis t h a t 1 2 muscle t e n s i o n l e v e l s of competitive a t h l e t e s are markedly-elevated p r i o r to competition. The purpose of the second experiment was to determine whether the increases i n muscle t e n s i o n of the magnitude observed i n a t h l e t e s p r i o r to comp-e t i t i o n were s u f f i c i e n t to d i s r u p t the performance of three s e l e c t e d motor t a s k s . Hypotheses (1) Competitive a t h l e t e s have elevated muscle t e n s i o n l e v e l s p r i o r to a competitive event. (2) Induced muscle t e n s i o n l e v e l s of the magnitude recorded i n Experiment 1 d i s r u p t the performance of motor a c t i v i t e s . D e f i n i t i o n of Terms 1. Electromyograph (EMG). When a muscle f i b e r i s a c t i v a t e d by a nervous impulse a r r i v i n g a t the neuromuscular j u n c t i o n , a p o s i t i v e 5-to-10 msec, 50-to-100 mV change i n membrane p o t e n t i a l precedes c o n t r a c t i o n . This a l l - o r - n o t h i n g e l e c t r i c a l change across the membrane of a s i n g l e muscle f i b e r i s c a l l e d a muscle a c t i o n p o t e n t i a l . The sumr,over time of numerous a c t i o n p o t e n t i a l s recorded by p l a c i n g gross sur-face e l e c t r o d e s over, or i n s e r t i n g needle ele c t r o d e s i n t o , a muscle i s c a l l e d an electromyograph. 2. Root-Mean-Square (RMS). RMS i s a s o p h i s t i c a t e d and s e n s i t i v e method of q u a n t i f y i n g the EMG. This form of 3 a n a l y s i s provides a measure of the t o t a l area under the EMG curve, or waveform and i s thus s e n s i t i v e to the d u r a t i o n of i n d i v i d u a l waves as w e l l as t h e i r magnitude and frequency. 3 . Biofeedback. Biofeedback i n v o l v e s p r o v i d i n g subjects w i t h immediate and accurate i n f o r m a t i o n about changes i n t h e i r p h y s i o l o g i c a l s t a t e , thus p r o v i d i n g them wit h a b a s i s f o r a c c u r a t e l y c o n t r o l l i n g the f u n c t i o n s being measured. U s u a l l y the feedback i s provided i n the form of a u d i t o r y or v i s u a l s i g n a l s . D e l i m i t a t i o n s The d e l i m i t a t i o n s are: 1. Experiment 1 i s d e l i m i t e d to competitive c o l l e g i a t e w r e s t l e r s . 2 . Experiment 2 i s d e l i m i t e d to male under-graduate p h y s i c a l education students. 3 . The r e s u l t s of Experiment 2 are d e l i m i t e d to the three motor tasks s e l e c t e d . 4 . The r e s u l t s of Experiment 2 are d e l i m i t e d to the s p e c i f i c muscle te n s i o n ranges s e l e c t e d ( i . e . 0 . 5 uV to 1 0 . 5 uV). L i m i t a t i o n s The l i m i t a t i o n s are: 1. The EMG a c t i v i t y of the w r e s t l e r s p a r t i c i -p a t i n g i n Experiment 1 was monitored approximately 1 hour before the competitive w r e s t l i n g event. 2 . I n Experiment 2, muscle t e n s i o n was i n -duced i n the r i g h t forearm of the subjects f o r periods ranging from 10 to 40 minutes. J u s t i f i c a t i o n of the Study I f p o s i t i v e r e s u l t s are i n d i c a t e d , the r e s u l t s of the present s t u d i e s w i l l provide a b a s i s f o r f u t u r e work i n v o l v i n g EMG biofeedback r e l a x a t i o n techniques. Thus, r e -search extending from t h i s t h e s i s may e v e n t u a l l y provide a method f o r improving a t h l e t i c performance by c o n t r o l l i n g a t h l e t e s ' pre-competition l e v e l s of muscle t e n s i o n . Chapter 2 REVIEW OF THE LITERATURE I n t r o d u c t i o n This chapter i s d i v i d e d i n t o two s e c t i o n s . The purpose of the f i r s t i s to provide the reader with an under-standing of the physiology of muscle ten s i o n , how muscle t e n s i o n has t y p i c a l l y been measured, and how muscle te n s i o n can be c o n t r o l l e d by biofeedback. In the second s e c t i o n , s t u d i e s of the r e l a t i o n s h i p between muscle tension and per-formance are reviewed and the relevance of these s t u d i e s to the present i n v e s t i g a t i o n s i s discussed. S e c t i o n I: Physiology, Measurement, and Biofeedback C o n t r o l  of Muscle Tension ' Physiology. The normal r e s t i n g membrane p o t e n t i a l of i n d i v i d u a l s k e l e t a l muscle f i b e r s i s about minus 85 mV; that i s , i n i t s r e s t i n g s t a t e the i n s i d e i s 85 mV negative to the outside. When a muscle f i b e r i s a c t i v a t e d by a nerv-ous impulse a r r i v i n g a t the neuromuscular j u n c t i o n , a pos-i t i v e 5-to - 1 0 msec, 5 0-to - 1 0 0 mV change i n membrane p o t e n t i a l precedes c o n t r a c t i o n (Guyton, 1971)• This a l l - o r - n o t h i n g e l e c t r i c a l change across the membrane of a s i n g l e muscle f i b e r i s c a l l e d a muscle a c t i o n p o t e n t i a l (deVries, 1976) . 6 The a c t i v i t y of i n d i v i d u a l muscle f i b e r s i s r a r e l y recorded i n - b e h a v i o u r a l experiments. Instead summated ac-t i v i t y of many muscle f i b e r s i s recorded through gross e l e c t r o d e s which are, i n most cases, f i x e d to the surface of the s k i n (Basmajian, 1974). The raw electromyograph (EMG) obtained by p l a c i n g surface e l e c t r o d e s over a whole muscle i s t y p i c a l l y a composite of the muscle a c t i o n po-t e n t i a l s of f i b e r s belonging to many motor u n i t s (Thompson, L i n d s l e y , and Eason, 1 9 6 6 ) . Increased n e u r a l input i n t o a muscle can r e s u l t i n increased a c t i v a t i o n of the p r e v i o u s l y a c t i v e f i b e r s , an increase i n the number of f i b e r s being a c t i v a t e d , or a combination of both. As n e u r a l input to a muscle increases three b a s i c changes i n the raw EMG s i g n a l can occur: there can be increases i n the p o t e n t i a l d i f f e r e n c e between the p o s i t i v e and negative waves, increases i n the frequency of the waves, and increases i n the average d u r a t i o n of i n d i v i d u a l waves (Guyton, 1971)• I t should be emphasized that the EMG i s not a d i -r e c t measure of the degree of muscular c o n t r a c t i o n . However, there i s , under normal c o n d i t i o n s , an extremely high c o r r e l a -t i o n between the e l e c t r i c discharge of a motor u n i t and the muscular c o n t r a c t i o n that f o l l o w s (Thompson et a l . , 1 9 6 6 ) . Measurement of muscle t e n s i o n . S e v e r a l d i f f e r e n t methods of e s t i m a t i n g muscle t e n s i o n l e v e l s have been de-veloped. P r i o r to the development of the electromyogram, 7 i n v e s t i g a t o r s had t h e i r subjects p u l l weights of v a r y i n g loads i n an attempt to induce muscle t e n s i o n . They i m p l i c -i t l y assumed that the amount of weight p u l l e d would be pro-p o r t i o n a l to the r e s u l t i n g muscle tension l e v e l s and th a t the l e v e l s of induced t e n s i o n would be the same f o r d i f f e r e n t i n d i v i d u a l s i f they p u l l e d the same weight load. Obviously such i n d i r e c t methods are inadequate, and i t i s unfortunate t h a t these methods were employed i n most of the e a r l y studies of the r e l a t i o n s h i p between muscle tension and performance ( 1 9 3 0 - 1 9 6 0 ) . The EMG techniques f o r d i r e c t l y measuring the e l e c -t r i c a l a c t i v i t y of muscles were widely adopted around i 9 6 0 . I n i t i a l l y i n v e s t i g a t o r s photographed the d i s p l a y of raw EMG s i g n a l s from an o s c i l l o s c o p e screen and estimated 'the average' amplitude of the waves. Considering the complexity of the EMG waveform, i t i s not s u r p r i s i n g that such s u b j e c t i v e methods were e v e n t u a l l y abandoned. More o b j e c t i v e methods of q u a n t i f y i n g the raw EMG s i g n a l are now used i n most research. I n each case the raw s i g n a l i s a u t o m a t i c a l l y analyzed and the r e s u l t s are graph-i c a l l y d i s p l a y e d . However, there are three b a s i c a l l y d i f -f e r e n t methods of a n a l y z i n g the EMG s i g n a l (James & Horton, 1 9 7 6 ) . The f i r s t and most simple method i s s e n s i t i v e to only the average p o t e n t i a l d i f f e r e n c e between the p o s i t i v e and the negative peaks of the raw EMG s i g n a l . The obvious problem wi t h t h i s 'peak-to-peak* method i s that i t i s not 8 s e n s i t i v e to increases i n the number of waves, nor i s i t s e n s i t i v e to increases i n the d u r a t i o n of the i n d i v i d u a l waves comprising the EMG s i g n a l . The second method of quan-t i f y i n g EMG s i g n a l s i s s e n s i t i v e to both the height and the frequency of the EMG waves. Since the c i r c u i t r y r e q u i r e d f o r t h i s 'integral-average' a n a l y s i s i s b a s i c a l l y q u i t e simple, i t has been used e x t e n s i v e l y . However, t h i s method of a n a l y s i s i s not s e n s i t i v e to changes i n the d u r a t i o n of i n d i v i d u a l waves. The t h i r d and most s e n s i t i v e measure of muscle ten-s i o n i s the root-mean-square (RMS) method. This form of a n a l y s i s provides a measure of the t o t a l area under the EMG curve, and i s thus s e n s i t i v e to the d u r a t i o n of i n d i v i d u a l waves as w e l l as t h e i r magnitude and frequency. Thus, t h i s method of a n a l y z i n g the EMG s i g n a l i s more s e n s i t i v e to changes i n muscle t e n s i o n than are the other two (James & Horton, 19?6). This RMS method of EMG q u a n t i f i c a t i o n was employed i n both s t u d i e s comprising the present thesis,-. Biofeedback c o n t r o l of muscle t e n s i o n . The c o n t r o l of muscle t e n s i o n by biofeedback i s r e l a t e d to the present d i s c u s s i o n i n two ways. F i r s t , biofeedback was used i n Ex-periment 2 as a method of studying the r e l a t i o n s h i p between muscle t e n s i o n and performance; p r i o r to the t e s t of p e r f o r -mance subjects looked at a d i s p l a y of the muscle t e n s i o n i n t h e i r r i g h t forearm f l e x o r group and adjusted the te n s i o n to produce the d e s i r e d RMS readings. Second, as mentioned i n 9 the previous chapter, the general purpose of t h i s t h e s i s was to t e s t the f e a s i b i l i t y of u s i n g biofeedback techniques to improve a t h l e t i c performance. Biofeedback simply i n v o l v e s p r o v i d i n g subjects w i t h immediate and accurate i n f o r m a t i o n about changes i n t h e i r p h y s i o l o g i c a l s t a t e , thus p r o v i d i n g them with a b a s i s f o r a c c u r a t e l y c o n t r o l l i n g the f u n c t i o n s being measured. U s u a l l y the feedback i s provided i n the form of a u d i t o r y or v i s u a l s i g n a l s . For example, Budzynski, Stoyva, and A l d e r (197.0) attached surface e l e c t r o d e s to the f r o n t a l i s muscle of f i v e hypertensive i n d i v i d u a l s and 'fed-them-back' a tone with a frequency p r o p o r t i o n a l to the average peak-to-peak EMG a c t -i v i t y of t h e i r f r o n t a l i s muscles. The subjects soon learned to lower the ten s i o n l e v e l s of the f r o n t a l i s muscles i n the l a b o r a t o r y s i t u a t i o n , and t h i s reduction r e s u l t e d i n a dimin u t i o n of the as s o c i a t e d headache a c t i v i t y . Haynes, Mosely, and McGowan ( 1 9 7 5 ) and Budzynski and Stoyva (1969) showed th a t subjects p r a c t i c i n g biofeedback could l e a r n to reduce muscle t e n s i o n l e v e l s b e t t e r and f a s t e r than c o n t r o l groups t r y i n g to r e l a x on t h e i r own. Hardyck, P e t r i n o v i c h , and E l l s w o r t h ( 1 9 6 6 ) , Budzynski and Stoyva ( 1970, and Bud-zy n s k i et a l . (1971) found that both the redu c t i o n of f r o n t a l i s EMG a c t i v i t y and the diminution of headaches were enduring consequences of biofeedback which c a r r i e d over to the su b j e c t s ' l i v e s outside the l a b o r a t o r y environ-ment. 10 A major impetus f o r biofeedback research was pro-vided by the c l a i m of M i l l e r (1969) and DiCara (1970) that c u r a r i z e d animals could c o n t r o l a v a r i e t y of autonomic func-t i o n s . P r e v i o u s l y i t had been assumed th a t such autonomic f u n c t i o n s could not be brought under v o l u n t a r y c o n t r o l , and as a r e s u l t t h i s work sti m u l a t e d i n t e r e s t i n the e n t i r e area of biofeedback. Although some of M i l l e r and DiCara's autonomic condi-t i o n i n g experiments have turned out to be c o n t r o v e r s i a l ( c f . Blanchard & Young, 1974), EMG biofeedback has been repeatedly shown to improve a v a r i e t y of be h a v i o u r a l problems. For example, M a r i n a c c i and Horande ( i 9 6 0 ) and Andrews (1964) t r a i n e d p a t e i n t s to move paralyzed muscles. The p a r a l y s i s had been caused by e i t h e r a stroke or motor nerve i n j u r y and had i n each case remained unresponsive to conventional methods of neuromuscular r e h a b i l i t a t i o n f o r over a year.. In both s t u d i e s needle ele c t r o d e s were i n s e r t e d i n the para-l y z e d muscles and the p a t i e n t s were provided w i t h feedback i n the form of a tone w i t h a volume p r o p o r t i o n a l to the peak-to-peak EMG a c t i v i t y . The subjects were t r a i n e d to increase the sound, thereby generating movement, and w i t h i n one t r a i n i n g s e ssion a l l s ubjects i n both s t u d i e s developed strong, v o l u n t a r y , w e l l modulated responses i n the p r e v i o u s l y p a r a l y z e d muscles. In another example of the e f f e c t i v e c l i n i c a l ap-p l i c a t i o n of EMG biofeedback, Hardyck, P e t r i n o v i c h , and E l l s w o r t h (1966) completely a b o l i s h e d s u b v o c a l i z a t i o n (the movement of the l a r y n g e a l muscles while reading s i l e n t l y ) , which s e r i o u s l y reduces reading speed (Blanchard & Young, 1974). Although the s u b v o c a l i z a t i o n d i s p l a y e d by the 17 c h i l d r e n i n the Hardyck, P e t r i n o v i c h , and E l l s w o r t h study had proved r e f r a c t o r y to other types of i n t e r v a t i o n , b i o -feedback was completely s u c c e s s f u l i n a l l 17 cases. The feedback was i n the form of an a u d i t o r y tone with a f r e -quency p r o p o r t i o n a l to the peak-to-peak EMG a c t i v i t y of the l a r y n g e a l muscles. Moreover, none of the subjects "sub-v o c a l i z e d " during follow-up t e s t s conducted 1 or 3 months l a t e r . Thus, biofeedback has proven e f f e c t i v e i n h e l p i n g subjects g a i n c o n t r o l over t h e i r s p e c i f i c muscular s t a t e w i t h r e s u l t i n g b e n e f i c i a l c l i n i c a l e f f e c t s i n s e v e r a l i n s t a n c e s . Although other techniques such as progressive r e l a x a t i o n (Jacobson, 1 9 3 8 ) , systematic d e s e n s i t i z a t i o n (Wolpe, 1 9 5 8 ) , and autogenic t r a i n i n g (Luthe, 1968) have been used to pro-duce a l t e r a t i o n s i n muscle t e n s i o n l e v e l s , biofeedback's e f f i c a c y coupled w i t h i t s inherent p r e c i s i o n and o b j e c t i v i t y make i t s u p e r i o r as both a research and c l i n i c a l t o o l . S e c t i o n I I : The Relevance of the L i t e r a t u r e R e l a t i n g  Muscle Tension and Performance Although the r e s u l t s of most of the e x i s t i n g s t u d i e s support the general assumption that muscle t e n s i o n can have an e f f e c t on performance, a thorough a n a l y s i s of the ex-1 2 perimental l i t e r a t u r e on the r e l a t i o n between muscle ten-s i o n and performance d i d not r e v e a l a s i n g l e study d i r e c t l y r e l e v a n t to the a p p l i e d goals of the present t h e s i s . There are two main features of the l i t e r a t u r e which preclude any p o s s i b i l i t y of a p p l y i n g i t to the goals of the present t h e s i s . F i r s t , the methodology of previous s t u d i e s i n t h i s area has been g e n e r a l l y poor; and second, even when the design and methods of the st u d i e s were adequate, t h e i r r e s u l t s had l i t t l e d i r e c t relevance to the s p e c i f i c a p p l i e d goal of improving the performance of competitive a t h l e t e s . To i l l u s t r a t e these two problems the nine s t u d i e s judged to be the most r e l e v a n t to the purpose of t h i s t h e s i s are reviewed i n t h i s chapter. These s t u d i e s are l i s t e d and evaluated i n Table 1 i n r e l a t i o n to the present o b j e c t i v e s . The most obvious methodological inadequacy charac-t e r i s t i c of these s t u d i e s i s t h e i r f a i l u r e to measure muscle t e n s i o n l e v e l s a c c u r a t e l y . I n s i x of the nine s t u d i e s , sub-j e c t s p u l l e d weights or squeezed dynamometers and changes i n muscle t e n s i o n were assumed, while the measurement techniques used i n the other three s t u d i e s l e f t much to be d e s i r e d . For example, Freeman (1933) used a crude method of tendon deforma-t i o n and photography i n an attempt to q u a n t i f y muscle t e n s i o n l e v e l s . A l e v e r , s e r v i n g to depress the p a t e l l a r tendon, was connected w i t h an o p t i c a l system which magnified changes i n the tendon deformation. I t was assumed t h a t the degree of deformation provided an accurate estimate of the degree Table 1 Ev a l u a t i o n of Nine Studies of the R e l a t i o n s h i p Between Muscle Tension and Performance with Respect to the Applied. Goals of the Present Thesis Inves t iga tor R u s s e l l (1932) Freeman (1933) Stauffaeher (1937) Freeman (1938) Courts (19^2) B e l l (1959) Pinneo (1961) Smith (1964) Parker (1973) Were measures of EMG adequate (•) or inadequate (x) Was muscle tension induced before (*/) or dur ing (x) tasks Were appropriate (•) or inappropriate (x) muscle tension l e v e l s induced Were the subjects a th le tes (•") or nonathletes (x) Were the tasks d i r e c t l y .(•) r e -la ted to sports or not (x) Major f i n d i n g s b a l l t o s s i n g r e a c t i o n time nonsense s y l l a b l e s f inger o s c i l l a t i o n s V p u r s u i t r o t o r p u r s u i t r o t o r a u d i t o r y t r a c k i n g r e a c t i o n time time es t imat ion The degree of accuracy and the degree of t ens ion are i n v e r s e l y r e l a t e d Increased tens ion due to a n t i c i p a t i o n of task d i f f i c u l t y increases e f f i c i e n c y of r e a c t i o n Best performances noted at one-h a l f i n d i v i d u a l s maximum c o n t r a c t i o n Number of o s c i l l a t i o n s increases wi th increased t ens ion Best performances noted at one-e ighth and one -ha l f maximal c o n t r a c t i o n Nei ther tens ion or mot ivat ion a l t e r t e d performance L e v e l of muscle tens ion and ac t iva . t ion c l o s e l y r e l a t e d React ion and movement times f a s t e s t i n tens ion c o n d i t i o n s Most accurate performances occurred a t the 50# induced muscle tens ion l e v e l 1 4 of muscle t e n s i o n . Although Smith (1964) attempted to r e -cord EMG a c t i v i t y , the e l e c t r o d e s were so p o o r l y attached that they f e l l from the s k i n surface of every subject a f t e r only a few t r i a l s . I n the remaining t r i a l s he f e l t the muscles i n an attempt to estimate the amount of muscle ten-s i o n . Pinneo (1961) q u a n t i f i e d the EMG s i g n a l s u s i n g the o b j e c t i v e , but r e l a t i v e l y i n s e n s i t i v e , peak-to-peak method. Another methodological inadequacy stems from the f a c t that the authors of the nine a r t i c l e s r e q u i r e d subjects to perform one task to induce muscle t e n s i o n while a t the same time a s s e s s i n g performance on another. For example, i n s e v e r a l s t u d i e s subjects p u l l e d weights or squeezed dyna-mometers w i t h one arm while performing on a p u r s u i t r o t o r w i t h the other ( B e l l , 1 9 5 9 ; Courts, 1 9 4 2 ; Pinneo, 1 9 6 1 ) . The problem i s that a task, no matter how simple, i n e v i t a b l y i n t e r f e r e s w i t h the performance of another task b e i n g per-formed at the same time (Broadbent & Gregory, I 9 6 3 & 1 9 6 5 ) • Thus, d i s r u p t i o n of performance noted i n these s t u d i e s of muscle t e n s i o n may have been caused at l e a s t i n p a r t by the other a c t i v i t y ( i . e . squeezing or p u l l i n g ) r a t h e r than by the increases i n muscle t e n s i o n per se. Unfortunately, the appropriate c o n t r o l s were never included i n these s t u d i e s . to d i f f e r e n t i a t e between these two p o s s i b i l i t i e s . Even i f these s t u d i e s were without s e r i o u s method-o l o g i c a l problems, i t would s t i l l be d i f f i c u l t to apply t h e i r r e s u l t s to the p r a c t i c a l goals of the present t h e s i s . Be-15 cause none had a p p l i e d goals, t h e i r methods do not appear to have been s e l e c t e d w i t h p r a c t i c a l a p p l i c a t i o n s i n mind. For example, r e s t i n g muscle t e n s i o n l e v e l s r a r e l y exceed 10 uV RMS i n the p e r i o d p r i o r to competition ( c f . Experiment 1 ) , yet i n the nine s t u d i e s muscle t e n s i o n was induced by e x t e r n a l loads r e q u i r i n g muscle te n s i o n l e v e l s ranging from one eight h to maximal c o n t r a c t i o n equivalent to RMS EMG l e v e l s of 125 to 1000 uV. These values are obviously w e l l out of the normal r e s t i n g range. I n a d d i t i o n , i n many of the pre-vious s t u d i e s of muscle t e n s i o n and performance, the p e r f o r -mance studi e d had l i t t l e d i r e c t r e l a t i o n s h i p to a c t u a l a t h l e t i c events. For example, i n two of the nine s t u d i e s c i t e d , the e f f e c t of v a r y i n g muscle t e n s i o n on f i n g e r o s c i l l a t i o n s and time e s t i m a t i o n was assessed; whereas the l e a r n i n g of non-sense s y l l a b l e s was i n v e s t i g a t e d i n another. Moreover, as mentioned p r e v i o u s l y , i n a l l of the st u d i e s attempts were made to assess the e f f e c t s of v a r y i n g l e v e l s of muscle t e n s i o n d u r i n g the performance of the be h a v i o u r a l t e s t s . However, i n most cases i t would not be f e a s i b l e to apply such r e s u l t s to a c t u a l competitive events, nor would i t be p o s s i b l e , f o r e t h i c a l and t e c h n i c a l reasons, to record EMG a c t i v i t y during important a t h l e t i c competitions. I n view of the b a s i c nature of the goals of the pre-sent t h e s i s , i t i s i n t e r e s t i n g to consider why the l i t e r a t u r e contains no d i r e c t l y r e l e v a n t data. Many of the methodological 16 inadequacies are c l e a r l y r e l a t e d to the f a c t that most of the work was done before the development of accurate EMG techniques. For example, the electromyogram was only r a r e l y employed i n research before i960 (Basmajian, 1974) and RMS techniques were not commonly used u n t i l 1975- Other method-o l o g i c a l problems seem to be r e l a t e d to general l a c k of ex-perimental s o p h i s t i c a t i o n g e n e r a l l y c h a r a c t e r i s t i c of e a r l y research i n the b e h a v i o u r a l sciences. For example, both Courts (1942) and R u s s e l l (1932) reported group means without p r o v i d i n g the reader w i t h an estimate of the s i g n i f i c a n c e of the d i f f e r e n c e s between them, and they d i d not even provide i n f o r m a t i o n concerning the v a r i a b i l i t y of t h e i r data which would a l l o w readers to estimate the s i g n i f i c a n c e l e v e l s f o r themselves. The l a c k of a p p l i c a b i l i t y of the r e s u l t s to a p p l i e d problems seems to stem from a combination of two f a c t o r s . F i r s t , most of the work was t h e o r e t i c a l l y o riented and second, the t h e o r i e s which guided the research were vague and based on l i t t l e e m p i r i c a l evidence. For example, i m p l i c i t i n most e a r l y t h e o r i e s was the assumption t h a t s t a t e s of muscle t e n s i o n were c o n s i s t e n t throughout the body. However, r e -cent evidence has proven t h i s assumption to be i n c o r r e c t . Alexander (1975) recorded the EMG a c t i v i t y of the f r o n t a l i s , the forearm, and the c a l f muscles during EMG biofeedback sessions. Although the EMG a c t i v i t y of the f r o n t a l i s muscle was s i g n i f i c a n t l y reduced, the EMG r e d u c t i o n was not gener-a l i z e d to the other s i t e s . E a r l i e r t h e o r e t i c a l formulations of the r e l a t i o n between muscle t e n s i o n and performance a l s o f a i l e d to d i s t i n g u i s h between the e f f e c t s of muscle t e n s i o n on v a r i o u s kinds of behaviour. I t seems to have been im-p l i c i t l y assumed th a t changes i n muscle t e n s i o n would i n -fluence a l l behaviours i n the same way. Apparently, as a r e s u l t of the shortcomings of e a r l y t h e o r e t i c a l formulations of the r e l a t i o n between muscle te n s i o n and performance, e a r l y i n v e s t i g a t o r s seem to have given l i t t l e thought to the exact muscles they studied or to the'exact tasks used to assess the consequences of changes i n muscle t e n s i o n . The recording s i t e s and the beha v i o u r a l tasks seem to have been s e l e c t e d f o r t e c h n i c a l r a t h e r than l o g i c a l reasons. Chapter 3 METHODS AND PROCEDURES I n t r o d u c t i o n This chapter i s d i v i d e d i n t o two s e c t i o n s . The purpose of the f i r s t i s to provide the reader w i t h an understanding of the methods and procedures used i n Ex-periment 1 , while the purpose of the second i s to provide the reader w i t h the same inf o r m a t i o n regarding Experiment 2. SECTION I : METHODS AND PROCEDURES OF EXPERIMENT 1 Subjects Ten male students, a l l f i r s t team members of the 1 9 7 6 - 7 7 U n i v e r s i t y of B r i t i s h Columbia w r e s t l i n g squad, served as subjects i n Experiment 1 . Apparatus Muscle t e n s i o n was recorded using a Cyborg B L 9 3 3 dual d i s t r i b u t i v e p r o c e ssing system (Cyborg Corporation, Boston, Mass.) which c o n s i s t e d of a B L 9 0 0 processer and two J 3 3 modules. Three (two re c o r d i n g and one grounding) p l a s t i c rimmed s i l v e r - p l a t e d e l e c t r o d e s , a l l 1 - i n c h i n diameter, were used to record EMG a c t i v i t y . 18 19 Experimental Design The EMG a c t i v i t y of the 10 w r e s t l e r s was monitored during s i x d i f f e r e n t sessions. Sessions 1 to 5 took place on consecutive days while Session 6 occurred 2 to 4 days a f t e r Session 5* Sessions 1, 2 , 3 , 4, and 6 were p r i o r to team p r a c t i c e sessions while Session 5 was p r i o r to an i n t e r -c o l l e g i a t e w r e s t l i n g competition. The o b j e c t i v e of the ex-periment was to compare the EMG a c t i v i t y of the w r e s t l e r s recorded p r i o r to p r a c t i c e s w i t h t h a t recorded p r i o r to the competition. Thus, the design was a single-group, repeated-measures design with the independent v a r i a b l e being the s i x sessions and the dependent v a r i a b l e s being the i n t e g r a t e d RMS scores recorded from the r i g h t forearm f l e x o r and quad-r i c e p muscle groups. Procedures Each of the s i x sessions began a f t e r a 20-minute group warm-up p e r i o d comprised of l i g h t , t o t a l body f l e x -i b i l i t y e x e r c i s e s . Subjects were tes t e d i n d i v i d u a l l y i n the same order each day. Therefore, although there were d i f -ferences between subjects i n the i n t e r v a l between the end of the warm-up session and recording, the i n t e r v a l was reasonably c o n s i s t e n t from s e s s i o n to se s s i o n f o r each w r e s t l e r . P r i o r to Session 1 three marks were placed at 1-inch i n t e r v a l s on the l o n g i t u d i n a l a x i s of the surface of the r i g h t forearm f l e x o r group and at 5-inch i n t e r v a l s on the l o n g i t u d i n a l 20 a x i s of the a n t e r i o r surface of the r i g h t quadricep muscle group. At the beginning of each session the subjects were i n s t r u c t e d to remain standing while these s i t e s were pre-pared f o r e l e c t r o d e placement. P r e p a r a t i o n of these s i t e s i ncluded shaving, c l e a n s i n g , and abrading the s k i n surface to reduce the s k i n r e s i s t a n c e below 0.2 uV RMS as i n d i c a t e d by the sensor l i g h t s on the J 3 3 modules. A grounding e l e c -trode was placed between two r e c o r d i n g e l e c t r o d e s on each muscle s i t e . A f t e r electrode placement the f o l l o w i n g i n -s t r u c t i o n s were read to each subject: Please keep your eyes open and look s t r a i g h t ahead. Rest your arms across your thighs but do not a l l o w your hands to touch. Place your legs d i r e c t l y out f r o n t of your c h a i r and extend your knees u n t i l you are comfortable. Do not cross your l e g s . Please remain motionless u n t i l the end of the t e s t i n g s e s s i o n . The subjects were then allowed a 1-minute a c c l i m a t i z a t i o n p e r i o d a f t e r which the EMG a c t i v i t y of the r i g h t forearm f l e x o r group was monitored f o r one minute. In the subsequent 1-minute i n t e r v a l the EMG a c t i v i t y of the r i g h t quadricep muscle group was monitored. The values recorded were the l e v e l s of RMS EMG a c t i v i t y i n t e g r a t e d over each of the two 1-minute t e s t i n g p e r i o d s . S t a t i s t i c a l A n a l y s i s A repeated measures a n a l y s i s of variance was used to evaluate the s i g n i f i c a n c e of t h e . r e s u l t s ( U n i v e r s i t y of B r i t i s h Columbia computer program, BMD:P2V). The EMG values 21 i recorded from the forearm and quadricep muscle groups were analyzed independently. SECTION H i METHODS AND PROCEDURES OF EXPERIMENT 2 Subjects Twelve male undergraduate p h y s i c a l education stud-ents, randomly s e l e c t e d from a group of volunteers, served as subjects f o r Experiment 2 . Experimental Design Each subject was t e s t e d i n d i v i d u a l l y during three d i f f e r e n t s e s s i o n s . Each s e s s i o n l a s t e d 4-0 minutes and 40 seconds w i t h e x t r a time a l l o t e d f o r electrode placement. There was a t l e a s t 24 hours between sessions. During each s e s s i o n the subjects were re q u i r e d to perform the same three motor t e s t s , 1) a Hand-Steadiness Test, 2) a Choice Response-Time Test, and 3) a Grip-Strength Test; however, the muscle t e n s i o n l e v e l each subject adopted i n h i s r i g h t forearm f l e x o r group was d i f f e r e n t d u r i n g each of the three sessions. (Note: Muscle t e n s i o n was not induced i n the quadricep muscle group as there was no' . s i g n i f i c a n t increase i n i t s t e n s i o n as noted i n the r e s u l t s s e c t i o n of Experiment 1 . ) The subjects assumed the appropriate t e n s i o n l e v e l — l o w ( 0 . 5 - 1 . 0 uV), medium ( 4 . 5 - 5 - 5 uV), or high ( 9 - 5 - 1 0 . 5 u V ) — with the a i d of biofeedback. The te n s i o n l e v e l the sub-j e c t s were r e q u i r e d to adopt during each of the three sessions was determined according to a 3 X 6 l a t i n square (Table 2) Table 2 \ L a t i n Square Design of Experiment 2 "Subjects Session 1 Session 2 Session 3 1 & 7 L a M b H c 2 & 8 L H M 3 & 9 M L H & 10 M H L 5 & 11 H L M 6 & 12 H M L L a= Low t e n s i o n c o n d i t i o n Mb= Medium t e n s i o n c o n d i t i o n Hc= High t e n s i o n c o n d i t i o n 23 to ensure the randomization of any order e f f e c t s . This design was repeated twice during Experiment 2. At the beginning of each of the i n d i v i d u a l t e s t i n g sessions the subjects were i n s t r u c t e d to view the EMG d i s p l a y and adopt the appropriate t e n s i o n l e v e l f o r a 10-minute p e r i o d (biofeedback p e r i o d ) . During the next 5 minutes each subject completed the Hand-Steadiness Test. F o l l o w i n g t h i s f i r s t t e s t p e r i o d each subject assumed the appropriate tension l e v e l f o r another 10-minute biofeedback p e r i o d before the second t e s t , the Choice Response-Time Test, that l a s t e d 6 minutes and 4-0 seconds. The t h i r d t e s t , the 5-minute Grip-Strength Test followed a t h i r d 10-minute biofeedback p e r i o d . The temporal sequence followed d u r i n g each t e s t i n g s e s s i o n i s i l l u s t r a t e d diagrammatically i n Figure 1. Procedures At the beginning of each t e s t i n g session the e l e c -trodes were attached to the r i g h t forearm f l e x o r group and the subjects were seated as i n Experiment 1. The EMG r e -cording equipment was a l s o the same as t h a t used i n the f i r s t experiment. During the biofeedback periods of each t e s t i n g ses-s i o n the subjects were i n s t r u c t e d to c o n t r o l the l e v e l of muscle t e n s i o n i n t h e i r r i g h t forearm f l e x o r group. The subjects a t t a i n e d the d e s i r e d tension c o n d i t i o n by watching the EMG meter and a d j u s t i n g the readings to the appropriate values. When the subjects were t e s t e d under the High 24 Figure 1. Diagrammatic r e p r e s e n t a t i o n of the temporal sequence of events during each t e s t i n g s e s s i o n . 25 TEST PERIODS BIOFEEDBACK PERIODS I 1 TOTAL TESTING SESSION i r 10 5 10 6:40 10 MINUTES HAND-STEADINESS TEST — » - 1—4 I I I I 1— I 1 10 50 10 50 10 50 10 50 10 50 SECONDS CHOICE RESPONSE-TIME TEST — i — f — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i -RESPONSE: 20-SEC INTERVALS GRIP-STRENGTH TEST 5 55 5 55 5 55 5 55 5 55 SECONDS 26 c o n d i t i o n , they were i n s t r u c t e d to watch the EMG meter and a d j u s t the t e n s i o n of the r i g h t forearm f l e x o r group u n t i l the needle f e l l mid-way "between the l i m i t s of 9»5 and 1 0 . 5 uV as marked on the s c a l e . This l e v e l , i . e . 10 uV RMS, approx-imates the highest t e n s i o n l e v e l s observed i n subjects i n Experiment 1. The same general procedures were followed when the subjects were t e s t e d under the Medium or Low t e n s i o n con-d i t i o n s but, of course, the c r i t i c a l yalues were d i f f e r e n t . The Medium t e n s i o n values were between 4 . 5 and 5*5 uV. I n the Low t e n s i o n c o n d i t i o n subjects were asked to produce as low a reading as p o s s i b l e . This always produced values be-tween 0 .5 and 1.0 uV. The average ' r e s t i n g * l e v e l before biofeedback was approximately 1.2 uV. A l l subjects were able to c o n s i s t e n t l y maintain the EMG l e v e l s i n the appropriate ranges w i t h the needle r a r e l y v a r y i n g more than a few tenths of a m i c r o v o l t during the biofeedback p e r i o d s . A f t e r a c h i e v i n g the appropriate l e v e l of t e n s i o n and maintaining i t fore 10 minutes, each subject was presented w i t h the f i r s t of three motor t e s t s . Test 1: Hand-Steadiness Test. Immediately f o l -lowing the f i r s t 10-minute biofeedback p e r i o d , the subjects were i n s t r u c t e d to p i c k up a 10 cm s t y l u s needle (Lafayette I n s t . Co., L a f a y e t t e , Ind.) w i t h a t i p diameter of 1 mm and place i t i n a 1.5-mm hole i n a s t y l u s rack (Lafayette I n s t . Co.). The subjects were i n s t r u c t e d to keep the s t y l u s needle 27 i n the centre of the opening a v o i d i n g contact with the edge. Every time the s t y l u s touched the side of the opening a d i g i t a l counter (Lafayette I n s t . Co., model #58024) r e -corded the event, while the t o t a l time the needle touched the side was cum u l a t i v e l y recorded on a sweep second c l o c k . There were a t o t a l of f i v e 10-second t r i a l s admin-i s t e r e d during t h i s Hand-Steadiness Test. Each of the f i v e t r i a l s was a u t o m a t i c a l l y terminated by a repeat c y c l e timer (Lafayette I n s t . Co., Model #51013) at which time the number of touches and the time on t a r g e t f o r the preceding 10-second p e r i o d were recorded. The subjects were not provided w i t h any v e r b a l feedback p e r t a i n i n g to the accuracy of t h e i r performance. Between each of the f i v e 10-second t e s t i n g p eriods there was a 50-second p e r i o d d u r i n g which the sub-j e c t s released the s t y l u s and maintained the appropriate t e n s i o n i n t h e i r forearm by r e f e r r i n g to the EMG meter. Figure 1 provides a diagrammatic i l l u s t r a t i o n of the sequence of events i n v o l v e d i n the Hand-Steadiness Test. Test 2 : Choice Response-Time Test. J u s t p r i o r to the t e r m i n a t i o n of the second 10-minute biofeedback p e r i o d a pressure switch was attached to the experimental c h a i r between the legs of the sub j e c t . In t h i s p o s i t i o n each sub-j e c t could e a s i l y place h i s r i g h t hand on the pressure switch and s t i l l maintain the appropriate t e n s i o n l e v e l . I t was from t h i s p o s i t i o n that each of the 20 choice response-time t r i a l s began. 28 At the end of the second 10-minute biofeedback p e r i o d each subject was i n s t r u c t e d to look at a stimulus panel. The beginning of each of the 20 choice response-time t r i a l s was a u t o m a t i c a l l y s i g n a l l e d by a green warning l i g h t followed 1.5 seconds l a t e r by one of two red l i g h t s i n d i c a t i n g which response was to take p l a c e . I f the l i g h t on the r i g h t of the stimulus panel appeared, each subject pressed a key to the r i g h t of a r e a c t i o n time console p o s i t i o n e d at arm's le n g t h . I f a l i g h t on the l e f t appeared, the l e f t key on the console was pressed; The sequence of 10 r i g h t and 10 l e f t responses was determined randomly and was d i f f e r e n t f o r each of the three t e s t i n g s e s s i o n s . There were three d i f f e r e n t measures of performance on t h i s Choice Response-Time Test: 1) Reaction Time, 2) Movement Time, and 3) T o t a l Reaction Time. The values f o r these three measures were determined by two d i g i t a l c l o c k s (Lafayette I n s t . Co., Model #54517). Both c l o c k s s t a r t e d on the p r e s e n t a t i o n of a red l i g h t and the f i r s t stopped as soon as the r i g h t hand was l i f t e d from the s t a r t i n g po-s i t i o n pressure switch. The reading from t h i s c l o c k i n -d i c a t e d r e a c t i o n time, the time from the stimulus to the f i r s t overt movement i n response to the stimulus. The sec-ond c l o c k stopped once the appropriate response key was pressed. T o t a l r e a c t i o n time was the time between the pre-s e n t a t i o n of the stimulus to the c e s s a t i o n of the second c l o c k . Reaction time was subtracted from the t o t a l r e a c t i o n time to produce movement time, the time from the f i r s t overt movement to the completion of the response. A f t e r each of the 20 t r i a l s each subject was i n -s t r u c t e d to r e t u r n h i s r i g h t arm to the s t a r t i n g p o s i t i o n pressure switch and check the EMG meter to insure that the EMG reading returned to the appropriate l e v e l . One t r i a l was i n i t i a t e d every 20 seconds, th e r e f o r e the e n t i r e Choice Response-Time Test l a s t e d 6 minutes and 4-0 seconds (see Figure 1). Test 3 : Grip-Strength Test. In the f i n a l 30 seconds of the t h i r d 10-minute biofeedback p e r i o d a g r i p a d j u s t a b l e hand dynamometer (Lafayette I n s t . Co., Model #76618) was placed i n the r i g h t hand of each subject. The subjects were i n s t r u c t e d to squeeze the dynamometer as f o r c e f u l l y as pos-s i b l e on the p r e s e n t a t i o n of a 5-second cue l i g h t (C.H. S t o e l t i n g Co., Model 20104, Chicago, 111.) and to s u s t a i n t h i s c o n t r a c t i o n u n t i l the l i g h t was extinguished. A p a t t e r n of the force of c o n t r a c t i o n was e l e c t r i c a l l y transduced and recorded by a chart recorder. The highest c o n t r a c t i o n value of the p a t t e r n was subtracted from the lowest during each t r i a l producing a measure of f a t i g u e . Maximal c o n t r a c t i o n of each t r i a l was recorded from the dynamometer face. Thus, there were two measures of st r e n g t h f o r each t r i a l . F ive 5-second t r i a l s were administered w i t h f o u r 55-second b i o -30 feedback periods i n t e r j e c t e d between the t r i a l s (see Figure 1). S t a t i s t i c a l A n a l y s i s A mean over t r i a l s f o r each of the three t e n s i o n c o n d i t i o n s on the two measures of hand s t a b i l i t y , the three measures of speed of response, and the two measures of g r i p s t r e n g t h were computed f o r each subject. These means were then independently subjected to a m u l t i v a r i a t e and u n i v a r i a t e a n a l y s i s of variance (Finn, 1972) to assess the s i g n i f i c a n c e of the v a r i a t i o n i n scores. This a n a l y s i s r e s u l t e d i n a m u l t i v a r i a t e F r a t i o which i n d i c a t e d the o v e r a l l s i g n i f i c a n c e of each of the three t e s t s while pre-planned orthogonal c o n t r a s t s were performed on each measure of the three t e s t s . The means recorded i n the Low c o n d i t i o n were compared with the means of the Medium and High c o n d i t i o n s combined, and the Medium c o n d i t i o n was compared w i t h the High. Chapter 4 RESULTS AND DISCUSSION Resu l t s of Experiment 1 Figure 2 c l e a r l y i n d i c a t e s that the o v e r a l l l e v e l of EMG a c t i v i t y was greater i n the forearm f l e x o r group than i n the quadricep muscle group. I t i s a l s o c l e a r from t h i s f i g u r e t h a t the muscle tension of the forearm f l e x o r i n -creased a p p r e c i a b l y p r i o r to the competition but the EMG a c t i v i t y of the quadriceps d i d not. S t a t i s t i c a l a n a l y s i s confirmed the s i g n i f i c a n c e of these d i f f e r e n c e s . I n order to determine the s i g n i f i c a n c e of the o v e r a l l d i f f e r e n c e i n EMG l e v e l s between the forearm f l e x o r and quadricep muscle groups, the mean EMG l e v e l s f o r both s i t e s were computed f o r each subject over the s i x sessions (see Table 3)- The average scores of the forearm f l e x o r s were higher than the average scores of the quadricep muscles f o r a l l ten subjects ( s i g n t e s t , N=10, X=0, p=0.002). In f a c t , there was only one instance during the e n t i r e exper-iment when the EMG value recorded from the quadricep muscles was higher than that recorded from the forearm f l e x o r s . The large increase i n EMG a c t i v i t y of the forearm f l e x o r s on Session 5 i p r i o r to the competition, was r e f l e c t e d i n a s i g -31 32 Figure 2. P r e - p r a c t i c e and pre-competition l e v e l s of muscle tension i n the forearm f l e x o r and quadricep muscle groups. Each p o i n t represents the mean RMS EMG a c t i v i t y i n t e g r a t e d over the e n t i r e 1-minute t e s t i n g s e s s i o n . 33 3k Table 3 EMG A c t i v i t y of the Forearm and Quadricep Muscles Recorded During the S i x Testing Sessions^ Sessions _ _ _ _ . _ _ Subjects arm l e g arm l e g arm l e g arm l e g arm l e g arm l e g 51 2 . 4 1.2 3 .1 1.4 2 .1 1.4 1.3 0.8 4 . 5 1.1 2 .1 1.3 5 2 1.3 0 .6 0 . 9 0 .6 0 . 9 0.7 2 .3 0 .6 6 .1 1.0 ' 1 . 4 0 .7 53 5 . 0 0.8 1.9 0.8 2 . 0 0 .7 6 . 4 0 .7 7.8 1.4 2 . 7 0 . 9 Sjj. 1.71 . 1 1 . 5 0 . 9 1.40.7 1 . 9 0 . 9 2 . 3 0 . 7 1.1 0 .6 55 1.8 0 .6 1.3 0 .6 3 . 4 0 .6 5 .0 0 .6 6 .7 0 .5 3 .3 0 .5 56 1.5 1.1 1.4 0.8 2 . 5 1.4 1.4 1.2 1.8 1.7 0 .9 0.8 Sy 4 . 0 0 .6 3 . 6 1.0 2 . 6 0 .7 2.7 1.0 3 . 5 1.0 1.7 0 . 9 SQ 5 - 0 2 . 1 2 . 4 1 . 8 1 . 9 0 . 7 2 . 5 1 . 9 6 . 3 0 . 6 3 . 0 1 . 2 S 9 2 . 3 0 . 8 2 . 5 0 . 6 2 . 4 0 . 7 1 . 4 0 . 5 4 . o o . 6 ; 2'.2 0 .7 S 1 0 1 ' 6 1'5 1'7 1.5 1.2 1.3 1.8 1.0 2 . 9 1.0 1.7 1.2 Mean 2 . 6 1.1 2 . 0 1.0 2 . 0 0 . 9 2 . 7 0 . 9 4 . 6 1.0 2 . 0 0 . 9 S.D. 1.5 0 .5 0 . 9 0 . 4 0 .7 0 .3 1.7 0 . 4 2 . 0 0 . 4 0 .8 0 .3 Each number i s the mean RMS EMG l e v e l i n uV i n t e g r a t e d over the e n t i r e 1-minute t e s t i n g session 35 n i f i c a n t v a r i a t i o n i n the EMG a c t i v i t y of the forearm f l e x o r over the s i x t e s t i n g sessions (Table 4 , ^ = 9 . 8 6 , p= 0 . 0 0 0 5 ) , whereas the v a r i a t i o n i n the EMG of the quadriceps muscles was not s i g n i f i c a n t (Table 5» F^ ^ = 0 . 0 5 8 , p= 0 . 6 5 6 ) . D i s c u s s i o n of Experiment 1 The purpose of Experiment 1 was to provide support f o r the hypothesis that muscle t e n s i o n l e v e l s of competitive a t h l e t e s are elevated immediately p r i o r to competition. A l -though s u b j e c t i v e r e p o r t s of the an x i e t y experienced by many a t h l e t e s p r i o r to a competitive event and the extensive l i t -e r ature documenting the r e l a t i o n between s u b j e c t i v e s t a t e s of anx i e t y and increased muscle t e n s i o n ( c f . Selye, 1974) sup-ported such a view, there were no d i r e c t l y r e l e v a n t e m p i r i c a l data. Thus, Experiment 1 provides the f i r s t e m p i r i c a l evidence confirming the commonly held view ( c f . Zaichowsky, 1974) that increases i n muscle t e n s i o n occur i n a t h l e t e s p r i o r to a competitive event. A number of researchers have found that a v a r i e t y of s t r e s s f u l s i t u a t i o n s can cause an increase i n muscle t e n s i o n ; however, no st u d i e s of t h i s nature have been conducted w i t h experienced a t h l e t e s i n a c t u a l comp-e t i t i v e s i t u a t i o n s . Although the e x t r a p o l a t i o n from s t r e s s f u l l a b o r a t o r y s i t u a t i o n s to the competitive atmosphere of the p l a y i n g f i e l d may seem j u s t i f i e d , there are two reasons why such g e n e r a l i z a t i o n s can be questioned. F i r s t l y , experienced Table 4 ANOVA Table f o r the Forearm F l e x o r Muscle S i t e Source Degrees of freedom Mean Square (uV) F Prob. F exceeded Subjects 9 5 . 2 Sessions 5 9-9 9 .860 0 .000 E r r o r 45 1.2 Table 5 ANOVA Table f o r the Quadricep Muscle S i t e S ourc e Degrees of freedom Mean Square (uV) F Prob. F exceeded Subjects 9 0 .5 Sessions 5 0.1 0 .058 0 .656 E r r o r 45 0.1 37 competitive a t h l e t e s may e v e n t u a l l y habituate to competitive s i t u a t i o n s , thereby producing low l e v e l s of muscle te n s i o n even though they are i n a s t r e s s f u l competitive atmosphere. Secondly, those a t h l e t e s that do experience marked increases i n muscle t e n s i o n immediately p r i o r to competition may have d i f f i c u l t y becoming s u c c e s s f u l competitive a t h l e t e s , being e l i m i n a t e d by a process of n a t u r a l s e l e c t i o n . However, the f i n d i n g s of Experiment 1 have i n d i c a t e d t h a t , at l e a s t i n some ins t a n c e s , experienced competitive a t h l e t e s do d i s p l a y marked pre-competition increases i n the EMG a c t i v i t y of some of t h e i r muscles. Experiment 1 a l s o confirmed that the EMG a c t i v i t y r e -corded simultaneously from d i f f e r e n t s i t e s i s not n e c e s s a r i l y the same. As w e l l as f i n d i n g that the EMG a c t i v i t y of the forearm f l e x o r group was g e n e r a l l y higher than that of the quadricep muscle group, the EMG a c t i v i t y of the forearm i n -creased s i g n i f i c a n t l y i n the pre-competition i n t e r v a l while the a c t i v i t y of the quadricep d i d not. Both of these obser-v a t i o n s are c o n s i s t e n t w i t h previous r e p o r t s . -Alexander ( 1 9 7 5 )» f o r example, found that the peak-to-peak EMG a c t i v i t y of the forearm muscles was s i g n i f i c a n t l y higher than t h a t of the l e g , and that the EMG a c t i v i t y of the forearm f l u c t u a t e d s i g n i f i c a n t l y during EMG biofeedback r e l a x a t i o n sessions w h i l e the a c t i v i t y i n the l e g remained unchanged. He sug-gested t h a t the EMG a c t i v i t y of the l e g was so low that i t 38 was d i f f i c u l t to demonstrate f u r t h e r r e d u c t i o n s . However, t h i s does not e x p l a i n why increases i n quadricep EMG a c t i v i t y comparable to those recorded from the forearm were not ob-served i n Experiment 1. Such major d i f f e r e n c e s between the EMG a c t i v i t y of d i f f e r e n t muscles have both t h e o r e t i c a l and p r a c t i c a l im-p l i c a t i o n s . I n most t h e o r i e s of the r e l a t i o n between muscle . t e n s i o n and performance, such as the well-known inverted-U hypothesis ('Stauffacher, 1937). muscle t e n s i o n i s a u n i t a r y concept; there i s no attempt to r e l a t e l e v e l s of muscle ten-s i o n to p a r t i c u l a r muscle groups. However, on the b a s i s of the present observations, i t i s c l e a r that r e l a x i n g or t e n s i n g one muscle group does not n e c e s s a r i l y produce s i m i l a r changes i n other muscles of the body. Therefore, f u t u r e attempts to use the concept of muscle t e n s i o n to e x p l a i n or p r e d i c t behaviour should be based on the understanding th a t s p e c i f i c l e v e l s of muscle t e n s i o n are apparently c h a r a c t e r i s t i c of i n d i v i d u a l muscles, not i n d i v i d u a l s u b j e c t s . The major p r a c t i c a l i m p l i c a t i o n of the f i n d i n g that d i f f e r e n t muscles may have d i f f e r e n t muscle t e n s i o n l e v e l s i s t h a t any attempts to improve a t h l e t i c performance by con-t r o l l i n g muscle t e n s i o n i n the pre-competitive p e r i o d should be d i r e c t e d at the a c t i v i t y of the muscle groups predominantly i n v o l v e d i n the event i n question and those which have elevated l e v e l s of EMG a c t i v i t y p r i o r to competition. 39 R e s u l t s of Experiment 2 The r e s u l t s i n d i c a t e d t h a t high l e v e l s of muscle t e n s i o n p r i o r to t e s t i n g d i s r u p t e d the performance of the Hand-Steadiness and the Grip-Strength Tests, whereas the e f f e c t of muscle t e n s i o n on the Choice Response-Time Test was e q u i v o c a l . The r e s u l t s of the three motor t e s t s are reported i n d i v i d u a l l y i n separate s e c t i o n s below. Each i n -d i v i d u a l s e c t i o n i n c l u d e s 1) a graphic r e p r e s e n t a t i o n of the r e l a t i o n s h i p between the means of the measures derived from the t e s t i n question and the t e n s i o n l e v e l , 2) a t a b l e of the means and standard d e v i a t i o n s of the t e s t scores, and 3) a t a b l e of the s i g n i f i c a n c e values f o r the o v e r a l l t e s t and f o r the orthogonal c o n t r a s t s . Test 1: Hand-Steadiness Test. The r e s u l t s of the Hand-Steadiness Test are i l l u s t r a t e d i n Figure 3 and Table 6 while the r e s u l t s of the s t a t i s t i c a l analyses are pre-sented i n Table 7. Each of the two measures ( i . e . contacts w i t h the edge and time on t a r g e t ) i n d i c a t e s that performance was best i n the Low t e n s i o n c o n d i t i o n and worst i n the High t e n s i o n c o n d i t i o n . Thus the m u l t i v a r i a t e F was h i g h l y s i g -n i f i c a n t (F^ f 3 = 1 2 . 8 9 , p= 0 . 0 0 1 5 ) . The comparison of Low ten-s i o n c o n d i t i o n with the Medium and High c o n d i t i o n s combined was s i g n i f i c a n t f o r both measures of hand steadiness, (contacts w i t h edge, p=0.0001 ; time on t a r g e t , p= 0 . 0 0 0 l ) ; whereas, there was a s i g n i f i c a n t d i f f e r e n c e between the 40 Figure 3« R e l a t i o n "between performance on the Hand-Steadiness Test and antecedent l e v e l s of muscle t e n s i o n . Each p o i n t represents the average of 12 subjects over 5 t r i a l s . (Note: the "contacts w i t h edge" scale i s inverted.) 4 l Table 6 Means and. Standard D e v i a t i o n s f o r the Two Measures of Hand Steadiness ( i . e . Contacts With Edge and Time On Target). Tension Contacts w i t h edge Time on target (sec.) c o n d i t i o n Mean S.D. Mean S .D. L 13-7 8 . 23 8 . 7 5 0.82 M 18.9 5 . 9 9 8 . 06 0.82 H 22.1 5 .92 7.82 0 .67 Table 7 P r o b a b i l i t y Values f o r the Hand-Steadiness.Test p values Contrasts Contacts w i t h edge Time on t a r g e t L vs M-H 0.0001 0 .0001 M vs H 0 .0112 0 .3295 M u l t i v a r i a t e Fij , > 8 = 1 2 . 8 9 , p=0.0015 43 Medium and High c o n d i t i o n s i n terms of the contacts w i t h edge measure (p=0.0l), hut not i n terms of the time-on-target measure (p=0.3295). Test 2: Choice Response-Time Test. Figure 4 and Table 8 present the means of the three measures of the Choice Response-Time Test ( i . e . r e a c t i o n time, movement time, and t o t a l r e a c t i o n time) as a f u n c t i o n of the l e v e l of muscle t e n s i o n . Although the m u l t i v a r i a t e F r a t i o was s i g n i f -i c a n t (Table 9, Fg g = l l . l 6 , p=0.0049), a l l three p a i r s of orthogonal c o n t r a s t s were not (see Table 9)• However, the f a s t e s t average responses f o r each of the three measures were recorded i n the Medium t e n s i o n c o n d i t i o n . Test 38 Grip-Strength Test. The r e s u l t s of the Grip-Strength Test are i l l u s t r a t e d i n Figure 5 and Table 10 while the r e s u l t s of the s t a t i s t i c a l analyses are pre-sented i n Table 11. Each of the two measures of g r i p strength ( i . e . maximum score and f a t i g u e ) i n d i c a t e d that performance was best i n the Low te n s i o n c o n d i t i o n and worst i n the Medium and High c o n d i t i o n s . Thus, the m u l t i v a r i a t e F was h i g h l y s i g n i f i c a n t (F^ 3=6.61, p=0.0119). The only s i g n i f i c a n t orthogonal c o n t r a s t was that between the Low versus the combined Medium and High c o n d i t i o n s on the max-imum strength measure (p=0.0003). The Medium versus High c o n t r a s t s of t h i s same measure j u s t f a i l e d to reach s i g n i f -44 Figure 4. R e l a t i o n between performance on the Choice Response-Time Test and antecedent l e v e l s of muscle t e n s i o n . Each p o i n t represents the average of 12 subjects over 20 t r i a l s spaced 20 seconds apart. 45 0.5 o cu CO CO o Q -co L U OC 0.4 CL 0.3 CO A — A TOTAL REACTION TIME REACTION TIME MOVEMENT TIME Low Medium High TENSION CONDITION 46 Table 8 Means and Standard D e v i a t i o n s ( i n Seconds) For the Three Measures of Speed of Response Reaction time Movement time T o t a l time Tension c o n d i t i o n Mean S.D. Mean S.D. Mean S.D. L . 259 .036 .236 .052 .495 .082 M .249 .037 .225 .046 .483 .075 H .258 .033 .228 .041 .488 .064 Table 9 P r o b a b i l i t y Values f o r the Choice Response-Time Test p values Contrasts Reaction time Movement time T o t a l time L vs M-H 0 .1530 0.1298 0 .1037 M vs H 0.0880 0.9142 0.4562 M u l t i v a r i a t e F 6 6=11 .16 , p=0.0049 4 7 Figure 5- R e l a t i o n between performance on the Grip-Strength Test and antecedent l e v e l s of muscle t e n s i o n . Each p o i n t represents the average of 12 subjects over 5 t r i a l s . (Note: the " f a t i g u e " scale i s inverted.) 48 49 Table 10 Means and Standard D e v i a t i o n s ( i n Kilograms) For the Two Measures of Grip Strength Tension Maximum score Fatigue score C o n d i t i o n Mean S.D. Mean S.D. L 50.3 6.41 0 .79 2.32 M 47.3 6.83 3.52 6 .84 H ^5-7 • 4.82 2.91 4.19 Table 11 P r o b a b i l i t y Values f o r the Grip-Strength Test p value Contrasts Maximum score Fatigue score L vs M«H 0.0003 0.0898 M vs H O.O969 0.7423 M u l t i v a r i a t e F 4 ) 8 = 6 . 6 l , p=0.0119 50 icance (p=0.0969). Both orthogonal c o n t r a s t s of the f a t i g u e measure f a i l e d to reach s i g n i f i c a n c e . D i s c u s s i o n of Experiment 2 I n Experiment 1 muscle t e n s i o n l e v e l s as high as 10 uV RMS were observed i n c o l l e g i a t e w r e s t l e r s one hour p r i o r to a competitive event. However, a l l previous s t u d i e s of the r e l a t i o n s h i p between muscle t e n s i o n and performance included high t e n s i o n c o n d i t i o n s ranging from one eighth to maximal c o n t r a c t i o n . Such l e v e l s of c o n t r a c t i o n produced readings of 100 to 1000 uV RMS on.the apparatus employed i n the pre-sent t h e s i s , f a r above the highest l e v e l s recorded i n Ex-periment 1. Thus, although there are many re p o r t s i n the l i t e r a t u r e that high muscle t e n s i o n l e v e l s can d i s r u p t per-formance ( c f . R u s s e l l , 1932), there i s l i t t l e , i f any, evidence t h a t such d i s r u p t i o n can be produced by increases i n EMG a c t i v i t y w i t h i n the normal r e s t i n g range. Therefore, the purpose of Experiment 2 was to determine whether such increases i n muscle t e n s i o n could cause a d i s r u p t i o n i n the performance of the three motor t a s k s . The r e l a t i o n between antecedent l e v e l s of muscle t e n s i o n and performance was the same f o r both the Hand-Steadiness and Grip-Strength Tests. I n both cases medium and high l e v e l s of p r e - t r i a l muscle tension were a s s o c i a t e d w i t h poor performance. The r e s u l t s of the Choice Response-Test,were eq u i v o c a l ; none of the orthogonal c o n t r a s t s was s i g n i f i c a n t . 51 Although i t i s d i f f i c u l t to d i r e c t l y apply the r e -s u l t s of l a b o r a t o r y t e s t s of motor performance to r e a l comp-e t i t i v e s i t u a t i o n s , there are three reasons f o r suspecting that the s i g n i f i c a n t d i s r u p t i o n of performance produced by high l e v e l s of muscle t e n s i o n i n t h i s experiment may perhaps be even l e s s than t h a t o c c u r r i n g during some a t h l e t i c comp-e t i t i o n s . F i r s t l y , i n Experiment 1, the EMG a c t i v i t y of the w r e s t l e r s was monitored approximately 1 hour before r a t h e r than immediately p r i o r to t h e i r matches. I f one assumes tha t EMG l e v e l s increase with the approach of impending competition, there i s reason to b e l i e v e that the highest muscle t e n s i o n l e v e l s recorded i n Experiment 1, and repro-duced i n Experiment 2, were lower than those which would a c t u -a l l y occur i n the c r i t i c a l p e r i o d j u s t before competition. Secondly, i n Experiment 2, performance was di s r u p t e d a f t e r r e l a t i v e l y short periods of induced muscle t e n s i o n . These periods ranged from 10 minutes f o r the Hand-Steadiness Test to 40 minutes f o r the Grip-Strength Test. However, many a t h l e t e s , i n c l u d i n g the w r e s t l e r s of the f i r s t exper-iment, have commented that they seem tense days before " b i g " events. T h i r d l y , the t e s t s used i n Experiment 2 were simple i n comparison to the complex a c t i v i t i e s i n v o l v e d i n most s p o r t i n g events. 'The r e s u l t s of many experiments have e s t -a b l i s h e d t h a t the performance of simple tasks i s more d i f -52 f i c u l t to d i s r u p t than i s the performance of more complex t a s k s . Thus, the r e s u l t s of Experiment 2 s t r o n g l y suggest., that the elevated muscle tension l e v e l s experienced by a t h l e t e s p r i o r to a competitive event may d i s r u p t t h e i r performance. GENERAL DISCUSSION The general purpose of t h i s t h e s i s was to determine whether f u t u r e research i n v o l v i n g EMG biofeedback as a pre-competition muscle r e l a x a t i o n technique f o r competitive a t h l e t e s was warranted. More s p e c i f i c a l l y the goals were f i r s t t o determine i f there were increases i n the muscle te n s i o n of competing a t h l e t e s p r i o r to competition events, and second to determine whether such increases could a f f e c t the performance of motor t a s k s . The r e s u l t s of Experiment 1 e s t a b l i s h e d t h a t a s i g n i f i c a n t increase i n the l e v e l s of muscle t e n s i o n of the r i g h t forearm f l e x o r group d i d occur i n a t h l e t e s p r i o r to a competion event. I n Experiment 2 such increases i n muscle t e n s i o n d i s r u p t e d the performance of both the Hand-Steadiness and Grip-Strength Tests. Thus, the r e s u l t s of the present t h e s i s j u s t i f y f u t u r e research i n t o the use of the EMG biofeedback r e l a x a t i o n technique; a technique which w i l l h o p e f u l l y reduce competitive a t h l e t e s * pre-competition muscle tension l e v e l s thereby improving t h e i r a t h l e t i c performance. 5 3 Methodological Innovations The'experiments comprising the present t h e s i s d i f -fered from previous s t u d i e s of t h e , r e l a t i o n between muscle t e n s i o n and performance i n s e v e r a l important ways. Although the e f f e c t i v e n e s s of EMG biofeedback as a method of c o n t r o l -l i n g EMG a c t i v i t y i n c l i n i c a l s i t u a t i o n s had been w e l l e s t -a b l i s h e d , i t had never been used as a "research" t o o l i n the study of the r e l a t i o n s h i p between muscle t e n s i o n and per-formance. The use of t h i s biofeedback technique i n E x p e r i -ment 2 provided a method of v a r y i n g muscle t e n s i o n l e v e l s , f a r more accurate than methods used by previous i n v e s t i g a t o r s . The p r e c i s i o n of the study was a l s o improved by u s i n g the s e n s i t i v e RMS measure of EMG a c t i v i t y . This recording tech-nique had not been p r e v i o u s l y used i n i n v e s t i g a t i o n s of EMG-behaviour r e l a t i o n s . The present s t u d i e s apparently comprise the f i r s t attempt to study the r e l a t i o n s h i p between muscle t e n s i o n and performance i n such a way t h a t the r e s u l t s can be d i -r e c t l y a p p l i e d to the p r a c t i c a l problem of improving a t h l e t i c performance. This was accomplished by the adoption of s e v e r a l methodological innovations s p e c i f i c a l l y designed to increase the a p p l i c a b i l i t y of the r e s u l t s of the exper-iments. Muscle t e n s i o n l e v e l s of competitive a t h l e t e s were monitored i n the a c t u a l competitive s i t u a t i o n i n Experiment 1, and the e f f e c t s of "normal" v a r i a t i o n s i n muscle t e n s i o n on s p o r t - r e l a t e d tasks were studied i n Experiment 2; whereas, previous i n v e s t i g a t o r s i n t h i s area have used subjects se-l e c t e d from the student p o p u l a t i o n at larg e to study the e f f e c t s of extreme l e v e l s of muscle t e n s i o n on a r b i t r a r y motor and mental tas k s , always i n l a b o r a t o r y s i t u a t i o n s . Moreover, the muscle tension l e v e l s studied i n Experiment 2 were induced p r i o r to the performance of the be h a v i o u r a l t e s t s . Although the e f f e c t of high l e v e l s of muscle t e n s i o n on performance i s probably more d i s r u p t i v e when tension i s induced and experimental tasks are performed a t the same time, there i s l e s s opportunity f o r ap p l y i n g the r e s u l t s from such procedures to a c t u a l a t h l e t i c competition. Muscle Tension and Sub j e c t i v e Tension The word "te n s i o n " i s commonly used i n two d i f f e r e n t contexts. I t i s used to describe the s t a t e of an i n d i v i -dual's muscles or h i s mental or s u b j e c t i v e s t a t e . The f a c t that a s i n g l e term i s used i n both cases emphasizes the common tendency i n everyday s i t u a t i o n s to equate s u b j e c t i v e and muscular t e n s i o n and the tendency i n c l i n i c a l or exper-imental contexts to use measures of muscle t e n s i o n as a b a s i s f o r i n f e r r i n g the nature of an i n d i v i d u a l ' s s u b j e c t i v e s t a t e . However, the r e l a t i o n between muscular and subjec-t i v e t e n s i o n i s not a simple one, and thus, a d i s c u s s i o n of the r e l a t i o n between these two c o n d i t i o n s i s warranted here to c l a r i f y the i m p l i c a t i o n s of the present s t u d i e s . One of the main reasons f o r equating muscle t e n s i o n with s u b j e c t i v e t e n s i o n i s that a c h r o n i c a l l y high l e v e l of 5 5 -muscle t e n s i o n i s one of the many p e r i p h e r a l symptoms f r e -quently observed i n subjects complaining of high l e v e l s of s u b j e c t i v e t e n s i o n or a n x i e t y . For example, the s o - c a l l e d t e n s i o n headache which i s assumed to r e s u l t from the e f f e c t s of h i g h l e v e l s of muscular t e n s i o n of-the f r o n t a l i s muscle, f r e q u e n t l y recurs i n s u s c e p t i b l e p a t i e n t s only when they have been subjected to s t r e s s f u l s i t u a t i o n s (Budzynski, Stoyva, & A l d e r , 1970) . Perhaps the most common p r a c t i c a l a p p l i c a t i o n of the r e l a t i o n between muscle tension and sub-j e c t i v e t e n s i o n i s the s o - c a l l e d polygraph or l i e detector t e s t . B a s i c a l l y t h i s t e s t i n v o l v e s r e c o r d i n g a number of p h y s i o l o g i c a l c o r r e l a t e s of s u b j e c t i v e t e n s i o n or a n x i e t y i n a c o n t r o l l e d s i t u a t i o n i n which other f a c t o r s which can i n f l u e n c e these measures are " c o n t r o l l e d " . P r i o r to i n t e r -r o g a t i o n the subject i s seated i n a comfortable p o s i t i o n and i s i n s t r u c t e d to r e l a x . The assumption i s that i n such c o n t r o l l e d s i t u a t i o n s , the s u b j e c t i v e t e n s i o n a s s o c i a t e d w i t h t e l l i n g a l i e w i l l be r e f l e c t e d i n increased EMG a c t -i v i t y and changes i n other p e r i p h e r a l measures. The v a l i d i t y of t h i s assumption has been upheld i n a v a r i e t y of l a b o r a t o r y t e s t s ( c f . Smith, 1967)• Because there are c o r r e l a t i o n s between r e s t i n g EMG l e v e l s and s u b j e c t i v e s t a t e s of a n x i e t y or t e n s i o n , there has been a tendency to assume that the two are c a u s a l l y r e -l a t e d . While there i s no doubt that increases i n s u b j e c t i v e t e n s i o n of an i n d i v i d u a l can r e l i a b l y produce increases i n 56 muscle t e n s i o n when other f a c t o r s which can i n f l u e n c e muscle t e n s i o n are held constant, there i s no evidence that changes i n r e s t i n g EMG l e v e l s can d i r e c t l y produce changes i n l e v e l s of a n x i e t y . Apparently, at l e a s t w i t h respect to ten s i o n , the b r a i n c o n t r o l s the muscles and not v i c e versa. Never-t h e l e s s , s e v e r a l i n v e s t i g a t o r s have t r i e d to reduce a n x i e t y by u s i n g biofeedback to reduce EMG a c t i v i t y . The f u t i l i t y of the approach i s ' demonstrated by the study of Raskin et a l . (1973)' They used an EMG biofeedback technique to reduce the f r o n t a l i s muscle t e n s i o n l e v e l s of 10 subjects c l a s s e d as c h r o n i c a l l y tense i n d i v i d u a l s . The r e d u c t i o n of f r o n t a l i s muscle t e n s i o n reduced the incidence of t e n s i o n headaches and the r e l a t e d symptom of insomnia, but there was no r e -duc t i o n i n the su b j e c t s ' r e p o r t s of anx i e t y . Other attempts to reduce a n x i e t y by reducing muscle te n s i o n have a l s o been unsuccessful ( G a r r e t t & S i l v e r , 1972; Wickramasekera, 1972). S i m i l a r l y there was no reason to b e l i e v e from Exper-iment 2 that the var i o u s muscle te n s i o n l e v e l s assumed by the subjects had an e f f e c t on t h e i r s u b j e c t i v e s t a t e . Thus, apparently high l e v e l s of muscle te n s i o n , even when they are not a s s o c i a t e d with high l e v e l s of s u b j e c t i v e t e n s i o n , can d i s r u p t performance. Therefore, i n a c t u a l competitive s i t u a t i o n s such as that i n Experiment 1, when both muscle ten-s i o n and s u b j e c t i v e t e n s i o n are high, the biofeedback tech-nique can apparently be used to reduce muscle t e n s i o n but not su b j e c t i v e t e n s i o n (Raskin et a l . , 1973)- Although performance 57 might a l s o be improved by reducing s u b j e c t i v e t e n s i o n , t h i s i s c l e a r l y out of the realm of present i n v e s t i g a t i o n s . P h y s i o l o g i c a l Mechanisms Although i t was not the purpose of t h i s t h e s i s to elaborate on the p h y s i o l o g i c a l b a s i s of high l e v e l s of muscle t e n s i o n or of t h e i r d i s r u p t i v e e f f e c t s on performance, the present f i n d i n g s can be p a r t i a l l y i n t e g r a t e d i n t o current p h y s i o l o g i c a l t h e o r i e s . I t i s w e l l documented that the presence of p h y s i c a l of p s y c h o l o g i c a l s t r e s s can cause a l t e r a t i o n s i n i n d i v i d u a l s ' s u b j e c t i v e s t a t e s as w e l l as inducing a number of p e r i p h e r a l responses such as increased heart r a t e , elevated blood pres-sure, a c c e l e r a t e d blood flow to the t i s s u e s , and elevated blood glucose concentrations which are mediated by the r e -lease of the catacholamines n o r a d r e n a l i n and a d r e n a l i n from adrenergic f i b e r s of the sympathetic nervous system and from the adrenal medullae (Guyton, 1971). This increase i n c i r -c u l a t i n g n o r a d r e n a l i n and a d r e n a l i n may a l s o be responsible f o r the increased muscle t e n s i o n l e v e l s a s s o c i a t e d w i t h sub-j e c t i v e s t a t e s of s t r e s s . Hutter and Loewenstein (1955) i s o l a t e d the i l i o -f i b u l a r i s muscle and i t s e f f e r e n t sympathetic f i b e r s from a f r o g and bathed the muscle i n Ringer s o l u t i o n . A number of t e s t s were conducted to determine the e f f e c t of sel e c t e d chemical agents on the c o n t r a c t i l e p r o p e r t i e s of the muscle. They found a s i g n i f i c a n t increase i n the frequency of min-58 i a t u r e end-plate p o t e n t i a l s occurred f o l l o w i n g a d d i t i o n of n o r a d r e n a l i n or a d r e n a l i n to the Ringer s o l u t i o n "bathing the i s o l a t e d muscle. Therefore, the s y m p a t h e t i c a l l y mediated release of n o r a d r e n a l i n and a d r e n a l i n i n response to s t r e s s -f u l s i t u a t i o n s could be a f a c t o r i n the increased muscle te n s i o n commonly ass o c i a t e d w i t h s t r e s s f u l s i t u a t i o n s . The d i s r u p t i v e e f f e c t s of muscle t e n s i o n on the performance of the motor s k i l l s of Experiment 2 i s more d i f f i c u l t to e x p l a i n . Although i t i s tempting to i n t e r p r e t the r e s u l t s i n terms of nervous or muscular f a t i g u e , n e i t h e r e x p l a n a t i o n seems t o t a l l y s a t i s f a c t o r y . Demonstrable f a t i g u e i n muscles (Astrand, 1970; deVries, 1976) or i n the neurons which innervate them (Astrand, 1970; Merton, 1954) g e n e r a l l y r e q u i r e s much greater c o n t r a c t i o n over longer periods of time than i n Experiment 2. S t r a t e g i e s of A p p l i e d Research The two experiments comprising the present t h e s i s are best viewed as the f i r s t step i n a much l a r g e r p r o j e c t designed to improve the performance of a t h l e t e s by using EMG biofeedback techniques to reduce pre-competition l e v e l s of muscle t e n s i o n . Thus, i t i s appropriate to d i s c u s s the r e l a t i o n s h i p of the present s t u d i e s to the u l t i m a t e goal and the s t r a t e g i e s of f u t u r e research which may grow out of them. I n so doing i t i s advantageous to c o n t r a s t the a p p l i e d approach used i n the present s t u d i e s with the more 59 t h e o r e t i c a l l y o r i e n t e d approach th a t seems to c h a r a c t e r i z e research i n the area of p h y s i c a l education. I t i s i n t e r e s t i n g to note t h a t , although the area of p h y s i c a l education i s "by i t s very nature a p p l i e d , t h e o r e t i c a l research holds a more eminent p o s i t i o n than a p p l i e d r e s e a r c h — probably because of the i n f l u e n c e of r e l a t e d by more theo-r e t i c a l l y - o r i e n t e d d i s c i p l i n e s such as physiology and psych-o l o g y — a n d i s ther e f o r e funded to a greater extent. Because a p p l i e d research i s oft e n t e c h n i c a l l y complex yet co n c e p t u a l l y u n s o p h i s t i c a t e d , there i s a tendency i n most areas of,the be-h a v i o u r a l sciences to concentrate almost e x c l u s i v e l y on "pure" research conducted i n l a b o r a t o r y s e t t i n g s . Research on the question of EMG-behaviour r e l a t i o n s reviewed e a r l i e r i n Chapter k e f f e c t i v e l y i l l u s t r a t e s the p o i n t that i t i s f r e -quently d i f f i c u l t to apply the r e s u l t s of pure l a b o r a t o r y research to even the most b a s i c a p p l i e d i s s u e s . Thus, there i s c e r t a i n l y room i n an a p p l i e d d i s c i p l i n e such as p h y s i c a l education f o r more a p p l i e d research. Although previous s e c t i o n s of the present t h e s i s have s t r e s s e d the importance of research i n f i e l d s i t u a -t i o n s , i n v e s t i g a t o r s working i n such s e t t i n g s f r e q u e n t l y encounter a v a r i e t y of c o n t r o l problems which can be r e a d i l y circumvented i n the more c o n t r o l l e d confines of the l a b -oratory. Thus, " f i e l d " research is. f r e q u e n t l y unconvincing because of the l a c k of experimental c o n t r o l , but the r e s u l t s of c o n t r o l l e d l a b o r a t o r y s t u d i e s are f r e q u e n t l y d i f f i c u l t to apply to " r e a l - l i f e " s i t u a t i o n s . The present s t u d i e s 60 i l l u s t r a t e how l a b o r a t o r y and f i e l d s t u d i e s can be e f f e c t i v e l y combined. I s i t worthwhile embarking on a p r o j e c t designed to improve a t h l e t i c performance by reducing pre-competition muscle t e n s i o n l e v e l s ? The f i r s t step i n answering t h i s question was to determine whether competitive a t h l e t e s do i n f a c t have elevated muscle t e n s i o n l e v e l s p r i o r to comp-e t i t i o n . C l e a r l y the only way of answering t h i s question was to measure muscle t e n s i o n l e v e l s i n competitive a t h l e t e s p r i o r to a c t u a l competitive events. Once i t was e s t a b l i s h e d t h a t a t l e a s t some competitive a t h l e t e s have elevated muscle t e n s i o n l e v e l s p r i o r to competition, the next step was to determine whether such increases could d i s r u p t performance. Although t h i s question must a l s o be u l t i m a t e l y answered i n a c t u a l competitive s i t u a t i o n s , i n i t i a l l a b o r a t o r y i n v e s t i -g a t i o n i n t o the problem had two advantages. F i r s t l y , be-fore an experimenter should even consider d i s r u p t i n g the p r a c t i c e sessions of seriou s competitive a t h l e t e s , he or she should have reasonable evidence that the research w i l l a i d the a t h l e t e . Attempts to prematurely apply research ideas before they have been su b s t a n t i a t e d tend to reduce, the p o s s i b i l i t i e s of g a i n i n g the cooperation of subjects at a l a t e r date. Secondly, the question of the r e l a t i o n between muscle t e n s i o n and performance i s b a s i c a l l y a para-metric problem which can be more e f f e c t i v e l y s t u d i e d , at l e a s t i n i t i a l l y , i n a c o n t r o l l e d l a b o r a t o r y environment. 61 Now tha t Experiment 2 and the p r e l i m i n a r y s t u d i e s on which i t was based have provided some b a s i c i n f o r m a t i o n concerning the r e l a t i o n s h i p between muscle te n s i o n and performance, i t w i l l be e a s i e r to study t h i s r e l a t i o n i n a c t u a l a t h l e t i c environments. The next step i n t h i s p r o j e c t w i l l be to study the r e l a t i o n between muscle te n s i o n and performance i n a c t u a l competitive a t h l e t e s , and i f there i s a r e l a t i o n , to u l t i m a t e t r a i n these a t h l e t e s to assume those l e v e l s of EMG a c t i v i t y most conducive to good performance. Moving i n t o the " f i e l d " w i t h t h i s research w i l l i n v o l v e adopting a new experimental p r o t o c o l . Rather than studying the means of large groups of s u b j e c t s , the research w i l l centre around the a n a l y s i s of a few cooperative a t h l e t e s . The main concern w i l l be to f i n d what l e v e l s of EMG a c t i v i t y are most e f f e c t i v e f o r a p a r t i c u l a r a t h l e t e engaging i n a p a r t i c u l a r sport. At t h i s next stage group means w i l l be l a r g e l y i r r e l e v a n t . During e a r l y phases of t h i s f i n a l stage of research i t w i l l be important to s e l e c t subjects which are cooperative and are competing i n sports conducive to data c o l l e c t i o n . S k i l l s such as t a r g e t shooting, b a s e b a l l p i t c h i n g , shot-p u t t i n g , and b a s k e t b a l l free-throw shooting lend themselves to o b j e c t i v e i n v e s t i g a t i o n . The r e s u l t s of the present ex-periments suggest t h a t best r e s u l t s w i l l be obtained w i t h sports i n v o l v i n g hand steadiness and upper body str e n g t h . Chapter 6 SUMMARY AND CONCLUSIONS EMG "biofeedback has been used to t r a i n s u b j e c t s to c o n t r o l t h e i r l e v e l s of muscle t e n s i o n . The recent develop-ment of t h i s technique r a i s e d the p o s s i b i l i t y t h a t compet-i t i v e a t h l e t e s could enhance t h e i r performance by l e a r n i n g to c o n t r o l t h e i r l e v e l s of muscle t e n s i o n i n the period' p r i o r to competition. Although I t has been reported t h a t the presence of p s y c h o l o g i c a l or p h y s i o l o g i c a l s t r e s s o r s could cause an increase i n muscle t e n s i o n l e v e l s , there was no e m p i r i c a l evidence which demonstrated that such increases are experienced by competitive a t h l e t e s p r i o r to important events. I n Experiment 1 there was a s i g n i f i c a n t increase i n the muscle tension l e v e l s of competitive w r e s t l e r s p r i o r to an important match. Experiment 2 was then conducted to de-termine whether the increases i n muscle tension of the mag-nitude noted i n Experiment 1 were s u f f i c i e n t to d i s r u p t the performance of s p o r t - r e l a t e d motor t a s k s . The s u b j e c t s ' performance on a Hand-Steadiness, a Choice Response-Time, and a Grip-Strength Task was assessed a f t e r low, medium, or high t e n s i o n l e v e l s were assumed w i t h the a i d of EMG b i o -feedback. High antecedent l e v e l s of muscle t e n s i o n s i g -62 63 n i f i c a n t l y d i s r u p t e d the performance of "both the G r i p -Strength and the Hand-Steadiness Tests. Thus, the r e s u l t s of the present t h e s i s j u s t i f y f u t u r e research i n t o the use of the EMG biofeedback r e l a x a t i o n technique; a technique which w i l l h o p e f u l l y reduce competitive a t h l e t e s ' pre-competition muscle t e n s i o n l e v e l s , thereby improving t h e i r a t h l e t i c performance. REFERENCES Alexander, B. An experimental t e s t of assumptions r e l a t i n g the use of electromyographic biofeedback as a general r e l a x a t i o n technique. Psychophysiology, 1975, 12 (6), 656-662. ~ Andrews, J . Neuromuscular re-education of the hemiplegic w i t h the a i d of the electromyograph. Archives of  Physiology and Medical R e h a b i l i t a t i o n , 1964, 45, 530-Basmajian, J . Muscles A l i v e (3rd ed.). Baltimore: W i l l i a m s & W i l k i n s , 1974. B e l l , H. E f f e c t s of experimentally-induced muscular t e n s i o n and frequency of m o t i v a t i o n a l i n s t r u c t i o n s on p u r s u i t r o t o r performance. P e r c e p t u a l and Motor S k i l l s , 1959i 9, 111-115. : ~ Blanchard, E,, & Young, L. C l i n i c a l a p p l i c a t i o n s of b i o -feedback t r a i n i n g : a review of evidence. Archives of  General P s y c h i a t r y , 1974, 30, 573-589-Broadbent, D., & Gregory, M. D i v i s i o n of a t t e n t i o n and the d e c i s i o n theory of s i g n a l d e t e c t i o n . Proceedings of  the Royal S o c i e t y , 1963, 158, 222-231. Broadbent, D., & Gregory, M. On the i n t e r a c t i o n of S-R c o m p a t i b i l i t y w i t h other v a r i a b l e s a f f e c t i n g r e a c t i o n time. B r i t i s h J o u r n a l of Psychology, 1965, 56, 61-67. Budzynski, T., & Stoyva, J . An instrument f o r producing deep r e l a x a t i o n by means of analog i n f o r m a t i o n feed-back. 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Chronic a n x i e t y t r e a t e d by feedback-induced muscle r e l a x a t i o n : a p i l o t study. Archives of General P s y c h i a t r y , 1973, 28, 2 6 3 -2 6 6 . R u s s e l l , J . R e l a t i v e e f f i c i e n c y of r e l a x a t i o n and tension i n performing an act of s k i l l . J o u r n a l of General  Psychology, 1932, 6, 330-3^3-Selye, H. Str e s s Without D i s t r e s s . New York: J.B. L i p p i n c o t t , 1974. Smith, B. The polygraph. S c i e n t i f i c American, 1967, 216 ( 1 ) , 2 5 - 3 1 . : " Smith, L. E f f e c t of muscular s t r e t c h , t e n s i o n , and r e l a x a t i o n upon the r e a c t i o n time and speed of movement of a sup-ported limb. The Research Quarterly. 1964, 35 (4), 546-553. S t a u f f a c h e r , J . The e f f e c t of induced muscular t e n s i o n upon var i o u s phases of the l e a r n i n g process. J o u r n a l of Experimental Psychology, 1937, 21, 26-46. Thompson, R., L i n d s l e y , D., & Eason, R. Experimental Methods and Instrumentation i n Psychology (1st ed.). New York: McGraw-Hill, 1 9 6 6 . Wickramasekera, I . I n s t r u c t i o n s and EMG feedback i n systematic d e s e n s i t i z a t i o n : a case r e p o r t . Behavioural  Therapy, 1972, ^ , 4 6 0 - 4 6 5 . Wolpe, J . Psychotherapy by R e c i p r o c a l I n h i b i t i o n . Stanford: Stanford U n i v e r s i t y Press, 1958. Z aichowsky, L. Combating s t r e s s : what about r e l a x a t i o n t r a i n i n g and biofeedback? Mouvement, 1975, £, 3 0 9 - 3 1 2 . 

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