THE EFFECTS OF ELECTRICAL STIMULATION ON MUSCULAR STRENGTH AND ENDURANCE OF THE EXTENSOR MUSCLES OF TBI HAND B.P.E., U n i v e r s i t y of B r i t i s h Columbia, 1975 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR TfiE DEGREE OF MASTERS OF PHYSICAL EDUCATION i n THE FACULTY CF GRADUATE STUDIES SCHOOL OF PHYSICAL IDUCATIGN AND RECREATION WE ACCEPT THIS THESIS AS CONFORMING TO THE REQUIRED STANDARD U n i v e r s i t y Of B r i t i s h Columbia July,1978 T)BRUCE CLAY GOLDSMID, 1S78 by ERUCf C., GOLDSMID 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 the requ i rement s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h Co lumb ia , I ag ree that 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 f o r r e f e r e n c e and s tudy . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g 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 g r a n t e d by the Head o f my Department or by h i s r e p r e s e n t a t i v e s . It i s u n d e r s t o o d 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 g a i n s h a l l not be a l l o w e d w i thout my w r i t t e n p e r m i s s i o n . Department o f P h y s i c a l E d u c a t i o n The U n i v e r s i t y o f B r i t i s h Co lumbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date J u l y 1 9 7 8 ABSTBACT The main purpose of t h i s study was to observe the changes i n muscular s t r e n g t h and endurance o f the extensor muscles of the hand a f t e r the arm had been exposed t o e l e c t r i c a l s t i m u l a t i o n . Twenty-four u n i v e r s i t y students were chosen f o r t h i s study. The s u b j e c t s were d i v i d e d i n t o t h r e e groups o f eight,, attempting t o make each group homogeneous with r e s p e c t to t h e i r Maximal Vol u n t a r y I s c i t e t r i c C o n t r a c t i o n of the extensor muscles of the hand. A l l s u b j e c t s were t r a i n e d with the hand at 150 degrees with r e s p e c t to the forearm ( P o s i t i o n 1) . Group 1 (ES) r e c e i v e d f i v e minutes of e l e c t r i c a l s t i m u l a t i o n t o the d o r s a l s u r f a c e of the forearm each weekday f o r a f o u r week p e r i o d . The placement of the e l e c t r o d e s were at the musculotendonous a r e a of the extensor muscles of the hand. The i n t e n s i t y o f the f a r a d i c s t i m u l a t i o n was j u s t below the s u b j e c t s pain t h r e s h o l d . Each c o n t r a c t i o n i i e l i c i t e d by the e l e c t r i c a l s t i m u l a t i o n was f o r a d u r a t i o n of 880 msec, and the r e l a x a t i o n between each c o n t r a c t i o n was 1030 msec. Group 2 (VI) performed f o u r s e t s of e i g h t Maximal Voluntary C o n t r a c t i o n s , where each c o n t r a c t i o n was held f o r a d u r a t i o n of two seconds. T r a i n i n g took p l a c e on the Monday, Sednesday, and F r i d a y of each week f o r a f o u r week d u r a t i o n . Group 3 (ES+VIj performed the t r a i n i n g of Groups 1 and 2 f o r f o u r weeks. Subject s were t e s t e d f o r t h e i r Maximal Voluntary C o n t r a c t i o n i n both P o s i t i o n 1 and P o s i t i o n 2 {180 degrees with r e s p e c t to the forearm). Endurance was c a l c u l a t e d on the s u b j e c t s f a t i g u e curve. The time i n seconds to 65% of t h e i r MVC (for each t e s t i n g period) was used as a measure o f t h e i r r e l a t i v e endurance. The t e s t i n g of s t r e n g t h and endurance was done before any t r a i n i n g took p l a c e , a f t e r two weeks of t r a i n i n g , and a t the d u r a t i c r of the f o u r week p e r i o d . , S i g n i f i c a n t s t r e n g t h g a i n s occured i n a l l t h r e e groups between the Pre t e s t and Mid*Iost i n P o s i t i o n 1 and P o s i t i o n 2. i i i During the Mid-Post t r a i n i n g p e r i o d o n l y the ES+VI group had s i g n i f i c a n t s t r e n g t h gains i n P o s i t i o n 1; whereas i n P o s i t i o n 2 both the ES and ES+VI groups y i e l d e d s i g n i f i c a n t s t r e n g t h g a i n s . I t was i l l u s t r a t e d t h a t i n d i v i d u a l s t r e n g t h g a i n s i n the ES and VI groups were not a d d i t i v e i n e i t h e r p o s i t i o n t e s t e d , and t h a t one t r a i n i n g method i s not s i g n i f i c a n t l y b e t t e r than another when observing mean s t r e n g t h gains over time. During the four week t r a i n i n g p e r i o d the endurance of the muscles d i d not a l t e r s i g n i f i c a n t l y when l o c k i n g at the mean of a l l t h r e e groups. i v TABLE OF CONTENTS CHAPTIR PAGE I INTRODUCTION . ... ....,. . .... ... ......... ... ... , 1 II BEVI EH OF LIT EB ATO BE 13 I s o m e t r i c T r a i n i n g ....................... 13 E l e c t r i c a l S t i m u l a t i o n ................... 17 Muscle Hypertrophy ...........,........... 21 I I I METHODS AND PROCEDURE . . .... ...» ..... *V« . • • 25 IV RESULTS AND DISCUSSION .34 S e c t i o n 1 ................,...............35 S e c t i o n 2 ...... ................ ..........47 S e c t i o n 3 ................................49 V SUMMARY AND CONCICSIONS ..............,.......56 REFERENCES ...................................60 APPENDICIES ............,.. . ...............,..67 LIST OF TABLES TABLE PAGE 3:1 T r a i n i n g Schedule .............................32 3:2 Orthogonal C o n t r a s t s ...........33 4:1 Subject Data ................. .34 4:2 Force Exerted i n P o s i t i o n 1 ......35 4:3 ANOVA S t r e n g t h i n P o s i t i o n 1 ................«.37 4:4 Preplanned C o n t r a s t s ( P o s i t i o n 1) .............38 4:5 Force Exerted i n P o s i t i o n 2 .••,•....,.vv.«•* '*,»v? 4:6 ANDVA (Strength i n P o s i t i o n 2) 43 4:7 Preplanned C o n t r a s t s ( P o s i t i o n 2) .............44 4:8 Pre-Post Strength Cains .......47 4:9 CELL MEANS (ENDUBANCE; POSITION 1) ............ 50 4:10 CELL MEANS (ENDURANCE; POSITION 2) ,50 4:11 ANOVA (Endurance; E o s i t i o n 1) .......,.v r,v.*51 4:12 ANOVA (Endurance; P o s i t i o n 2) .................54 v i LIST OF FIGOSES FIGURE PAGE 1:1 F a r a d i c Current Pulse 8 1:2 S u p e r f i c i a l Muscles c f Forearm ................ 9 1:3 Deep Muscles of Forearm .......................11 2:1 Current Paths of S t i m u l a t i o n .................. 16 3:1 T e s t i n g Apparatus ..............* ..............28 4:1 Strength Graph ( P o s i t i o n 1) 36 4:2 Strength Graph ( P o s i t i o n 2) ................... 42 4:3 Endurance Graph ( P o s i t i o n 1) ..................52 4:4 Endurance Graph ( P o s i t i o n 2) .................. 53 v i i ACKNOWLEDGMENTS I would l i k e t o thank a l l the members c f my committee, Dr. K. Co u r t s , Dr. B. Schutz, Dr. P. Vaughn, and Dr. T. Rhodes f o r t h e i r guidance and p a t i e n c e d u r i n g t h i s e n t i r e study. I would a l s o l i k e t o thank Mrs. 6. 0 * S u l l i v a n f o r l e n d i n g me the e l e c t r i c a l s t i m u l a t o r and f o r g i v i n g me d i r e c t i o n d u r i n g some method o l o g i c a l problems. Thark God i t ' s f i n i s h e d ! ! v i i i Chapter 1 INTRODUCTION Numerous authors (Hansen, 1961; Basch, 1961) have s t a t e d t h a t i s o m e t r i c t r a i n i n g programs i n c r e a s e i s o m e t r i c s t r e n g t h . Myres {1967} and Basch et a l . (1961) f u r t h e r r e p o r t e d t h a t i s o m e t r i c s t r e n g t h i n c r e a s e s i n muscles u n r e l a t e d to the s p e c i f i c muscle l e n g t h at which i t was t r a i n e d . In order t o get s t r e n g t h i n c r e a s e s , v a r i o u s i n t e n s i t i e s and d u r a t i o n s of muscle c o n t r a c t i o n s are r e q u i r e d . d e V r i e s (1968) s t a t e s that t r a i n i n g procedures could undoubtedly be g r e a t l y improved i f we Knew p r e c i s e l y what g u a n t i t y and g u a l i t y o f st i m u l u s are r e q u i r e d to b r i n g about a t r a i n i n g e f f e c t . E a r l y s t u d i e s by H e t t i n g e r and K u l l e r (1953) suggested that the s t i m u l u s f o r s t r e n g t h i n c r e a s e s was a r e s u l t of oxygen d e f i c i t w i t h i n the muscle t i s s u e i n v o l v e d . ; Morehouse (1971:149) f e l t t h a t oxygen d e f i c i t was not the s t i m u l u s f o r s t r e n g t h i n c r e a s e s , 1 2 but f e l t i t was due to g o l g i tendon d e i n h i b i t i o n . He s t a t e d : " s i n c e the end p o i n t of a b r i e f maximal s t r e n g t h e f f o r t can be s e t by i n h i b i t o r y f u n c t i o n s , t r a i n i n g s hould be d i r e c t e d toward reducing the responsiveness o f i n h i b i t o r y c o n t r o l s . T h i s l e s s e n i n g of i n h i b i t o r y s e n s i t i v i t y would permit a higher degree of t e n s i o n to occur thus i n c r e a s i n g the s t r e n g t h c f the movement. Morehouse (1971) t h e o r i z e d t h a t the decrease i n i n h i b i t i o n i s due to a morphological a l t e r a t i o n i n the muscle t i s s u e , thus a l t e r i n g the discharge of the g o l g i tendon organs. He f e l t t h a t the t r a i n i n g s t i m u l u s r e s i d e d i n t h e c e n t r a l nervous system (CHS) and a t r a i n i n g e f f e c t was brought about by a r e d u c t i o n of normal i n h i b i t o r y e f f e c t s of the pyramidal system upon lower motor neurons. The only v a l i d method of t e s t i n g Morehouse's theory would be to r e c o r d g o l g i tendon organ a c t i v i t y a f t e r the l u s c l e had been s u b j e c t e d t c a s t r e n g t h t r a i n i n g program. Ss yet an experiment such as t h i s has not been c a r r i e d out, thus r e s e a r c h e r s have had t o look at i n d i r e c t evidence t o comment on Morehouse's t h e o r y . Some workers ( l u i and lewey, 1947 ; Ncwakcwska, 1962) have t r a i n e d muscles c a u s i n g i n v o l u n t a r y c o n t r a c t i o n s i n i t i a t e d by 3 e l e c t r i c a l s t i n s u l a t i o n . The e f f e c t which e l e c t r i c a l s t i m u l a t i o n has on muscle s t r e n g t h i s c o n t r o v e r s i a l , and Dev r i e s (1968) comments on s t u d i e s s i m i l a r t c these and f e e l s that the evidence supports the theory that the e f f e c t o n . i n c r e a s i n g muscular s t r e n g t h r e s i d e s both i n the CNS and the muscle t i s s u e i t s e l f . , A cause and e f f e c t r e l a t i o n s h i p seems to be apparent. The cause seems to be r e l a t e d t o the muscle (with changes i n the co n n e c t i v e t i s s u e ) a f f e c t i n g g o l g i tendon output. The e f f e c t i s an i n c r e a s e i n s t r e n g t h i n d i r e c t l y r e g u l a t e d by CMS output. Statement - of the Problem The purpose of t h i s i n v e s t i g a t i o n i s to q u a n t i f y the changes i n i s o m e t r i c s t r e n g t h and endurance of the extensor muscles of the hand a f t e r a f o u r week t r a i n i n g p e r i o d using e l e c t r i c a l s t i m u l a t i o n , v o l u n t a r y i s o m e t r i c c o n t r a c t i o n s , and a combination of both techniques. The subprcblem of t h i s experiment i s to observe the changes i n i s o m e t r i c s t r e n g t h and endurance of the extensor muscles o f the hand a t a d i f f e r e n t muscle l e n g t h other than the l e n g t h a t which i t was t r a i n e d . , S i g n i f i c a n c e c f the Study To date the e f f e c t of i n c r e a s i n g i s o m e t r i c s t r e n g t h using e l e c t r i c a l s t i m u l a t i o n has not been demonstrated. / T h i s study i n t e n d s t o q u a n t i f y the ext€nt to which i s o m e t r i c s t r e n g t h and endurance a l t e r with the use cf a s p e c i f i c t r a i n i n g program using e l e c t r i c a l s t i m u l a t i o n t o i n i t i a t e muscular c o n t r a c t i o n s . Hypotheses F o l l o w i n g a four week t r a i n i n g program: 1) I s o m e t r i c s t r e n g t h of the extensor muscles of the hand s i g n i f i c a n t l y i n c r e a s e s when v o l u n t a r y i s o m e t r i c , e l e c t r i c a l s t i m u l a t i o n , and vo l u n t a r y i s e m e t r i e • e l e c t r i c a l s t i m u l a t i o n 5 t r a i n i n g methods are used as d e s c r i b e d i n t h i s study. T h i s o c c u r s at both muscle lengths t e s t e d . 2) Muscles t r a i n e d both by voluntary i s c m e t r i c c o n t r a c t i o n and e l e c t r i c a l s t i m u l a t i o n experience the g r e a t e s t i n c r e a s e i n i s o m e t r i c s t r e n g t h as compared to the ether techniques. T h i s occurs a t both muscle l e n g t h s t e s t e d . 3) The i n c r e a s e i n i s o m e t r i c s t r e n g t h o f the extensor muscles of the hand using a combination of i s c m e t r i c v o l u n t a r y c o n t r a c t i o n and e l e c t r i c a l s t i m u l a t i c c are l e s s than the sum of the i n c r e a s e s brought about by each t r a i n i n g technique s e p a r a t e l y . T h i s occurs at both muscle lengths t e s t e d . 4) R e l a t i v e endurance of the extensor u u s c l e s of the hand does not i n c r e a s e due to any o f the t h r e e t r a i n i n g techniques a t both muscle l e n g t h s t e s t e d . , 6 D e l i m i t a t i o n s 1} I n f e r e n c e s from t h i s study should be l i i i t e d to male s u b j e c t s with normally i n n e r v a t e d s k e l e t a l muscles. 2) The energy requirements cf each t r a i n i n g technique have not been c a l c u l a t e d ; thus, c o n c l u s i o n s as t o the e f f i c i e n c y of the d i f f e r e n t t r a i n i n g techniques cannot be made. L i m i t a t i o n s 1} S u p e r f i c i a l muscles are s t i m u l a t e d t o a g r e a t e r degree than the deeper muscles and thus w i l l have a more pronounced c o n t r a c t i o n . 2) The i n t e n s i t y of e l e c t r i c a l s t i m u l a t i o n d i f f e r s s l i g h t l y f o r each s u b j e c t due to v a r i a t i o n s i n r e s i s t a n c e of s k i n and v a r i a t i o n s i n pain t h r e s h o l d . D e f i n i t i o n s ELECTRICAL STIMULATION : The e l e c t r i c a l s t i m u l a t i o n used i n t h i s study was a f a r a d i c c u r r e n t . The f a r a d i c c u r r e n t was produced 7 by a f a r a d i c c o i l and the c u r r e n t c o n s i s t e d of a r a p i d r i s e and f a l l of u n i d i r e c t i o n ( d i r e c t ) c u r r e n t . Impulses ranged from 86-88 per second. The r i s i n g phase of the impulse i s l e s s than one m i l l i s e c o n d and the recovery phase i s approximately 13 msec. The r a p i d r e c u r r e n c e o f these impulses throws and holds the sarcomeres which i t s t i m u l a t e s i n continued t e t a n i c c o n t r a c t i o n . The c u r r e n t i s a p p l i e d f o r a d u r a t i o n o f 880 msec and has a guiescen t p e r i o d of 1030 msec. ( F i g 1:1) ENDURANCE: Endurance i n t h i s study i s a r e l a t i v e measurement taken from each s u b j e c t * s f a t i g u e curve i n r e l a t i o n to t h e i r MVC during each t e s t i n g p e r i o d . EXTENSOR MUSCLES OF THE HAND: The primary muscles s t i m u l a t e d are: ( F i g 1:2 ; 1:3) 1) Extensor C a r p i R a d i a l i s B r e v i s 2) Extensor C a r p i R a d i a l i s Longus 3) Extensor C a r p i U l n a r i s 4) Extensor Digitorum 8 TIME DIVISION 2msec FIG 1:1 OSCfLI S C O P E TRAC ING OF O N E FARADIC. P U L S E 9 FIG 1:2 D O R S A L SURFACE OF F O R E A R M SUPERF IC IAL M U S C L E S 10 SUPERFICIAL MUSCLES 1) T r i c e p s B r a i c h i 2) B r a i c h i o r a d i a l i s 3) l a t e r a l E p i c o n d i l e 4) Extensor C a r p i R a d i a l i s Longus 5) Anconeus 6) Extensor D i g i t c r u m 7) Extensor C a r p i Ulnar i s 8) Extensor C a r p i R a d i a l i s B r e v i s 9) Extensor D i g i t i Minimi 10) Abductor P o l l i c u s Longus 11) Extensor P o l l i c i s Longus 12) Extensor P o l l i c u s Longus DEEP MUSCLES 12 BEIP MUSCLES 1) Humerus 2) L a t e r a l E p i c o n d i l e 3) Olecranon 4) Supinator 5) F l e x o r C a r p i U l n a r i s 6) Flexor D i g i t o r u a U l n a r i s 7) Adductor P o l l i c u s Longus 8) Extensor C a r p i E a d i a l i s B r e v i s 9 ) Extensor C a r p i E a d i a l i s Longus 1 0 } Extensor P o l l i c u s B r e v i s 11) Extensor P o l l i c u s Longus 1 2 ) Extensor I n d i e i s 13) Extensor C a r p i U l n a r i s 13 Chapter I I EJ I I I l g 91 LITSBATUBE ISCMETBIC TB JUNING a t h l e t e s and n o n - a t h l e t e s have always been i n t e r e s t e d i n techniques to i n c r e a s e s t r e n g t h and endurance of v a r i o u s muscle groups. I s o m e t r i c t r a i n i n g became r e c o g n i z e d as an e f f e c t i v e form of s t r e n g t h t r a i n i n g f o l l o w i n g the e a r l y experiments by H e t t i n g e r and fluller (1953). H e t t i n g e r and M u l l e r demonstrated t h a t a s i x second c o n t r a c t i o n of t w o - t h i r d s MVC was s u f f i c i e n t to y i e l d a s i g n i f i c a n t i n c r e a s e i n s t r e n g t h , and t h a t l i t t l e d i f f e r e n c e was observed i n s t r e n g t h g a i n s f o r another group t r a i n e d at 100% flVC. , L a t e r , Walters e t a l . , (1S60) demonstrated s i m i l a r f i n d i n g s u s i n g elbow f l e x o r s . The q u e s t i o n of s t r e n g t h i n c r e a s e s o c c u r r i n g only a t the s p e c i f i c j o i n t angle i s o m e t r i c a l l y t r a i n e d has been a c o n t r o v e r s i a l s u b j e c t f o r y e a r s , and authors have had 14 c o n f l i c t i n g r e s u l t s , p r i m a r i l y determined by the methodology o f t h e i r experiments. B o i l e a u (1962) t r a i n e d the elbow f l e x o r s of male s t u d e n t s at t w o - t h i r d s MVC f o r s i x seconds with the elbow at 175 degrees. F o l l o w i n g a two month t r a i n i n g s e s s i o n , i s o m e t r i c s t r e n g t h was measured at j o i n t angles of 175, 115, and 65 degrees. S i g n i f i c a n t i n c r e a s e s i n s t r e n g t h were o n l y found at the s p e c i f i c angle t r a i n e d . Meyers e t a l . , (1963) i s o m e t r i c a l l y t r a i n e d the arm ex t e n s o r s at 165 degrees and found t h a t s i g n i f i c a n t i n c r e a s e s i n s t r e n g t h occurred o n l y at 165 degrees and not a t 125 degrees. These two experiments suggest t h a t i s o m e t r i c s t r e n g t h gains occur o n l y at the s p e c i f i c angle t r a i n e d . There are some s t u d i e s which c o n t r a d i c t the f i n d i n g s o f B o i l e a u (1962) and Meyers et a l . , (1963). Meyers (1967) continued i n v e s t i g a t i n g t h i s problem and found arm f l e x o r s t r a i n e d i s o m e t r i c a l l y f o r a s i x week d u r a t i o n at 170 degrees y i e l d e d q u i t e d i f f e r e n t r e s u l t s than were expected. One group performed t h r e e MVC, each f o r s i x seconds. The experimental group performed 20 MVC, each held f o r s i x seconds. When t e s t e d 15 f o r i s o m e t r i c s t r e n g t h at 170 and 90 degrees, the second group showed s i g n i f i c a n t s t r e n g t h g a i n s a t both angles t e s t e d , where-as the f i r s t group demonstrated s t r e n g t h g a i n s only a t 170 degrees.. Sasch e t a l . , (1961) t r a i n e d elbow extensors i s o m e t r i c a l l y a t 90 degrees f o r s i x weeks, three times per week. S i g n i f i c a n t s t r e n g t h gains were found with the elbow a t 45, 90, and 135 degrees. In viewing the above l i t e r a t u r e on i s o m e t r i c t r a i n i n g with regard to j o i n t s p e c i f i c i t y , one would have to conclude t h a t i t i s s t i l l a c o n t r o v e r s i a l s u b j e c t , and o n l y a f t e r o b s e r v a t i o n s on the s p e c i f i c s o f each experiment could any c o n c l u s i o n be made. I t seems from both Meyers (1967) and Rasch's (1961) work t h a t the i n t e n s i t y of t r a i n i n g i s a c o n t r o l l i n g f a c t o r when observing s t r e n g t h i n c r e a s e s s p e c i f i c t o j o i n t angles t r a i n e d . 16 FIG 2:1 C O U R S E OF C U R R E N T PATHS B IPOLAR STIMULATION WITH 17 ELECTHICAL STIMULATION S t i l l w e l l (1967) mentions t h a t e l e c t r i c a l s t i m u l a t i o n s i m i l a r to the method used i n t h i s experiment s t i m u l a t e s sensory nerves, motor nerves and the e n t i r e a u s c l e ( F i g 2:1 ). With s u f f i c i e n t c u r r e n t , the motor nerves are s t i m u l a t e d c a u s i n g a muscle c o n t r a c t i o n to the muscles they s u p p l y . with d i r e c t muscle and nerve s t i m u l a t i o n a t a freguency above 50 impulses/second the muscle c o n t r a c t i o n i s t e t a n i c . F a t i g u e i n the muscle takes p l a c e q u i c k l y i f continued s t i m u l a t i o n i s e l i c i t e d ; t h e r e f o r e , o p t i n a l c u r r e n t i s a p u l s a t i n g c u r r e n t t o allow f o r seme re c o v e r y from the p r e v i o u s c o n t r a c t i o n s ( S t i l l w e l l (1967)) . E l e c t r i c a l s t i m u l a t i o n to a muscle causes s i m i l a r v a s c u l a r changes as a s s o c i a t e d with voluntary c o n t r a c t i o n . An i n c r e a s e i n the requirement f o r n u t r i e n t s occurs, as w e l l as an i n c r e a s e needed f o r removal of waste products. S t i l l w e l l (1967:127) s t a t e s : " I f a muscle c o n t r a c t s a s u f f i c i e n t number of times a g a i n s t a r e s i s t a c c e of an adequate l o a d there i s an i n c r e a s e i n the bulk of the 18 muscle f i b e r s and the muscle i s strengthened. There i s some doubt whether the muscle c o n t r a c t i o n caused by f a r a d i c s t i m u l a t i o n can produce these e f f e c t s , but presumably i f s u f f i c i e n t c o n t r a c t i o n s are produced a g a i n s t a r e s i s t a n c e o f an adeguate l o a d i t should be p o s s i b l e to do so" S t i l l w e l l was i n some doubt as t o the e f f e c t s of e l e c t r i c a l s t i m u l a t i o n p e r t a i n i n g t o s t r e n g t h i n c r e a s e s i n s k e l e t a l muscle. Very l i t t l e evidence has been gathered on the use of e l e c t r i c a l s t i m u l a t i o n on human s u b j e c t s ; thus, some i m p l i c a t i o n s r e g a r d i n g muscular a c t i v i t y had to be a p p l i e d from animal s t u d i e s . The use of e l e c t r i c a l s t i m u l a t i o n as a s t i m u l u s f o r atrophy r e t a r d a t i o n has been s t u d i e d by numerous authors. Guttman and Guttman (1942), noticed t h a t denervated r a b b i t muscle a t r o p h i e d l e s s when exposed to e l e c t r i c a l s t i m u l a t i o n . Osbourne (1951) r e v e a l e d decrease i n atrophy i n humans with l e s i o n s of p e r i p h e r a l nerves a f t e r exposed t o e l e c t r i c a l s t i m u l a t i o n . In other human s t u d i e s Jackson and Seddon (1945) demonstrated t h a t e l e c t r i c a l s t i m u l a t i o n to "the s m a l l muscles of the hand retarded atrophy d u r i n g the f i r s t 100 days of d e n e r v a t i o n and was almost completely e f f e c t i v e i n preventing wasting a f t e r t h i s time". 19 Other authors have not only demonstrated a decrease i n atrophy, but i l l u s t r a t e d a hypertrophy w i t h i n the muscle. L u i and Lewey (1947) used e l e c t r i c a l s t i m u l a t i o n ( s i n u s o i d a l wave) with a freguency o f e i g h t c y c l e s per second f o r ten minutes d a i l y f o r a month. E i g h t of the twenty-two denervated muscles i n e i g h t p a t i e n t s showed an i n c r e a s e i n volume. Osbourne e t al.,(1950) s t i m u l a t e d s u b j e c t s with p o l i o m y e l i t i s using a s i n u s o i d a l wave f o r ten minutes a day, and s i g n i f i c a n t i n c r e a s e s were demonstrated i n the c i r c u m f e r e n c e s of the limbs. Hore re c e n t l i t e r a t u r e by Peckham (1 976) i l l u s t r a t e d s i g n i f i c a n t s t r e n g t h gains i n q u a d r i p l e g i c p a t i e n t s when subjected to e l e c t r i c a l s t i m u l a t i o n , an i n t r a m u s c u l a r e l e c t r o d e was planted w i t h i n the muscle nerves which s t i m u l a t e d the muscle at 50% of i t s maximal f o r c e . The c o n t r a c t i o n was p r i m a r i l y by e x c i t a t i o n of i n t r a m u s c u l a r nerves and i t i s estimated t h a t only 5% of the muscular f o r c e was from d i r e c t muscle s t i m u l a t i o n . The s t i m u l a t i o n remained on f o r 2.5 seconds and o f f f o r the same d u r a t i o n . The hand was i n a l o c k e d p o s i t i o n and the f i n g e r f l e x o r s were s t i m u l a t e d f o r two t o three hours a day f o r 30 20 weeks. Even a f t e r f o u r weeks of s t i m u l a t i o n , s i g n i f i c a n t s t r e n g t h gains were observed. E l e c t r i c a l s t i m u l a t i o n i s not the only p r e r e q u i s i t e which causes changes i n the muscle. I t was i l l u s t r a t e d by S h a f f e r (1956) t h a t t e n s i o n development w i t h i n the muscle was mandatory i n order t h a t muscle weight and h i s t o l o g i c appearance a l t e r . Hines (1956) a l s o came up with s i m i l a r c o n c l u s i o n s . He recommended that the muscle be i n a s t r e t c h e d p o s i t i o n and under c o n d i t i o n s which would y i e l d maximum t e n s i o n development i n order t h a t e l e c t r i c a l s t i m u l a t i o n be at optimum c o n d i t i o n s . , The a p p l i c a t i o n of e l e c t r i c a l s t i m u l a t i o n i n t h i s study was a b i -p o l o r technigue where two e l e c t r o d e s o f egua l s i z e were a p p l i e d to the g e n e r a l area o f the o r i g i n and i n s e r t i o n of the muscle group to be s t i m u l a t e d . In t h i s manner the e n t i r e muscle i s permeated from the onset by a maximum c u r r e n t d e n s i t y . Thorn (1957) d e s c r i b e s t h i s method as being the most e f f e c t i v e when using b i - p o l o r techniques, as c u r r e n t passes l o n g i t u d i n a l l y through the muscle. The o p t i m a l d u r a t i o n of s t i m u l a t i o n has been s t u d i e d by 21 numerous authors (Solandt e t a l . , 1943; Kowarschik, 1952; and wakim e t a l . , 1955)., I t was concluded t h a t a b r i e f d u r a t i o n of s t i m u l a t i o n was as e f f e c t i v e as a long p e r i o d of s t i m u l a t i o n . S t i l l w e l l (1967) mentions that when f a t i g u e becomes predominant and adequate t e n s i o n can no longer be developed, e l e c t r i c a l s t i m u l a t i o n i s no longer b e n e f i c i a l . HUSCLE HYPEBTEOPHX The c o n t r a c t i l e a c t i v i t y of a muscle has been d i r e c t l y coupled to the s i z e of the muscle. i s hypertrophy w i t h i n the muscle takes plac e p r o t e i n uptake i n c r e a s e s w i t h i n the muscle. H i t h the a i d of nonmetabolized amino a c i d analog al p h a -a m i n o i s o b u t r i c (AIE) and B - o r o t i c a c i d , the p r o t e i n uptake ac r o s s the muscle membrane has been observed. T h i s p o r t i o n o f the l i t e r a t u r e review comments on the r e l e v a n t s t u d i e s concerning amino a c i d uptake i n order t o i l l u s t r a t e the e f f e c t s of e l e c t r i c a l s t i m u l a t i o n on the hypertrophy o f s k e l e t a l muscle. Studie s by A r v i l (1967) on i s o l a t e d l e v a t o r a n i muscle of a r a t demonstrated a s i g n i f i c a n t i n c r e a s e i n AIB-14C i n the muscle when su b j e c t e d to e l e c t r i c a l s t i m u l a t i o n . , The g r e a t e s t i n c r e a s e i n AIB was demonstrated when t h e muscle r e c e i v e d s t i m u l a t i o n a t 60 impulses/minute, a l t h o u g h AIB uptake was a l s o s i g n i f i c a n t a t 30 impulses/minute. Kendric and Jones (1967) demonstrated s i m i l a r f i n d i n g s using f r o g s a r t o r i u s muscle. P r o t e i n s y n t h e s i s was seen t o i n c r e a s e when the muscle was subjected t o repeated c o n t r a c t i l e a c t i v i t y i n i t i a t e d by e l e c t r i c a l s t i m u l a t i o n . Goldberg (1974) s t u d y i n g r a t hemidiaphragm demonstrated t h a t an e l e c t r i c a l s t i m u l a t i o n d u r a t i o n cf s i x minutes was adequate t o y i e l d s i g n i f i c a n t p r o t e i n c a t a b o l i s m . Goldberg went on to conclude that the e f f e c t s of e l e c t r i c a l s t i m u l a t i o n on AIB uptake were even g r e a t e r when the muscle was s t r e t c h e d t o 10-15$ beyond i t s r e s t i n g l e n g t h . The s t r e t c h i n g of the muscle holds the muscle a t a co n s t a n t l e n g t h , thus any e l e c t r i c a l s t i m u l a t i o n would y i e l d an i s o m e t r i c c o n t r a c t i o n . Goldberg (1974) found t h a t r a t hemidiaphragm had a more pronounced r a t e of AIB uptake 23 when c o n t r a c t i n g i s c m e t r i c a l l y as opposed to zero l o a d . In some hemidiaphragms there was no s i g n i f i c a n t i n c r e a s e i n the r a t e of AIB uptake with the muscle c o n t r a c t i n g a t zero l o a d . T h i s p o i n t supports Goldberg's (1974:307) c o n c l u s i o n : " t h a t the c o n t r a c t i l e work r a t h e r than the freguency of the a c t i o n p o t e n t i a l s or the r e l e a s e of n e u r o t r a n s m i t t e r i s the major s i g n a l f o r AIB uptake. These experiments s t r o n g l y suggest that t h e same bi o c h e m i c a l conseguence of the c o n t r a c t i l e process and not a n e u r a l event a f f e c t s the r a t e o f muscle hypertrophy." In order that muscles hypertrophy, muscle p r o t e i n uptake must be g r e a t e r than p r o t e i n degradation suggesting t h a t t e n s i o n c o n t r o l l e d by l e v e l of a c t i v i t y and s t r e t c h i n the muscle i n f l u e n c e the over a l l amino a c i d t r a n s p o r t . A study by J a t e l e c k i (1973) used H - o r c t i c a c i d as a measure of p r o t e i n uptake w i t h i n the muscle. He c l e a r l y demonstrated t h a t amino a c i d uptake i s p r i m a i r l y w i t h i n the c o n n e c t i v e t i s s u e s y i e l d i n g a production of e x t r a c e l l u l a r c o l l a g e n o u s matrix. From unpublished o b s e r v a t i o n s , Goldberg (1974) a l s o mentioned that BNA s y n t h e s i s i s concentrated at the d i s t a l p o r t i o n s of the muscle c l o s e s t t o the musculotendinous area of the muscle. Both the f i n d i n g s of J a t e l e c k i (19:73) and Goldberg (1974) i n d i r e c t l y support Morehouse*s (1965) d e i n h i b i t i o n theory of s t r e n g t h t r a i n i n g . , Morehouse p o s t u l a t e d , t h a t d u r i n g strength t r a i n i n g a t h i c k e n i n g of the c o n n e c t i v e t i s s u e takes p l a c e . I f t h i s i s so, any t e n s i o n w i t h i n a muscle would y i e l d decreased s t r e t c h s t i m u l u s to G o l g i organs l o c a t e d w i t h i n the tendon and c o n n e c t i v e t i s s u e of the muscle. The g o l g i tendon organs e l i c i t an i n h i b i t o r y discharge to the CNS and thus a c t as a b r a k i n g mechanism to the output of the muscle p e r c e i v i n g the s t r e t c h . , T h e r e f o r e , i n s t r e n g t h t r a i n i n g , be i t voluntary or imposed by e l e c t r i c a l s t i m u l a t i o n , hypertrophy i s seen to take p l a c e i n the muscle and c o n n e c t i v e t i s s u e . The i n c r e a s e i n the c o n n e c t i v e t i s s u e would dampen the output of the g o l g i tendon organs thus y i e l d i n g a decreased i n h i b i t i o n t o the CNS ; t h e r e f o r e , an i n c r e a s e d output t c the muscle from the CNS causing an i n c r e a s e i n t e n s i o n output from the muscle., 25 Chapter 3 METHODS AND PBOCIDOBE Twenty-four male, summer s c h o o l , U n i v e r s i t y of B r i t i s h Columbia s t u d e n t s were used i n t h i s experiment. The s u b j e c t s ranged i n age from 18 to 31 y e a r s . A l l s u b j e c t s were r i g h t handed and none were p a r t a k i n g i n any form of arm s t r e n g t h t r a i n i n g program p r i o r t o or during the experiment. T e s t i n g And Equipment Each s u b j e c t had h i s humerus i n a f l e x e d p o s i t i o n with the hand at the l e v e l of the shoulder. The forearm was i n an extended p o s i t i o n with the hand pronated. The e n t i r e arm l a y f l a t and was secured to the t e s t i n g t a b l e by s t r a p s l o c a t e d a t the d i s t a l ends of the forearm and humerus. The hand was i n a f l e x e d p o s i t i o n , 150 degrees with r e s p e c t to the forearm ( P o s i t i o n 1} . The hand (palm s i d e down) was 26 secured to a padded board with four one i n c h nylon s t r a p s over the back o f the f i n g e r s and hand (Fig 3 : 1 ) . The hand board p i v o t e d on a hinge which at t a c h e d to the t e s t i n g t a b l e , and the s t y l o i d process of the u l n a was p o s i t i o n e d over the hinge. Secured to the underside of t h e hand board was a 14 cm lo n g , 2 mm diameter c a b l e which was attached to a .5 cm t u r n b u c k l e . The turnbuckle was used t o take up the s l a c k i n the c a b l e . Secured to the t u r n b u c k l e was a D a t r o n i c Load C e l l (model 2500) which was used to measure the f o r c e e l i c i t e d by the e x t e n s i o n of the hand. A D a t r o n i c a m p l i f i e r ( IIode 1 720 ) was used as the power source f o r the l o a d c e l l and the output from the t r a n s d u c e r was c a l i b r a t e d and recorded on an M.F.£. Beeorder. The same apparatus was used to measure the f o r c e of the e x t e n s i o n of the hand when the handbcard and hand was at an angle of 180 degrees with r e s p e c t t o t h e forearm, t h i s was known as P o s i t i o n 2. The apparatus used to administer the e l e c t r i c a l s t i m u l a t i o n was an MBI f a r a d i c s t i m u l a t o r (Model 800). PROCEDURES A l l t e s t i n g and t r a i n i n g was done using the l e f t arm. Students were i n i t i a l l y t e s t e d to a c q u i r e t h e i r MVC as we l l as endurance of the extensor muscles of the hand. HVC was measured a c c o r d i n g t o t h e f o l l o w i n g c o n d i t i o n s ; < C a l d w e l l , 1974) . , 1) S t a t i c s t r e n g t h was assessed during a steady maximal e x e r t i o n f o r f o u r seconds. 2) The t r a n s i e n t p e r i o d of one second b e f o r e and a f t e r the steady e x e r t i o n was d i s r e g a r d e d . 3) S t r e n g t h datum was the mean score recorded d u r i n g the middle two seconds of the steady e x e r t i o n . 4) The f o r c e was expressed i n k i l o g r a m s . 5) The mean s c o r e o f the twc t r i a l s was used as datum. 6) One minute was giv e n between t r i a l s . 28 straps hand board load cell amplif i e r r—c 1 r e c o r d e r FIG 3:1 EST ING APPARATUS (POSITION 1) I s o m e t r i c endurance was measured i n the f o l l o w i n g manner: 1) S u b j e c t s were i n s t r u c t e d to c o n t r a c t the extensor muscles of the hand maximally i n an attempt t o l i f t the hand board. 2) Paper speed on the MFE r e c o r d e r was s e t at 20 cm/min. 3) S u b j e c t s were i n s t r u c t e d to r e l a x when the i s c m e t r i c t e n s i o n dropped below 65% o f t h e i r MVC., 4) The time i n seconds to 65% o f the s u b j e c t s MVC on the f a t i g u e curve «as used as the measure of endurance. The f i r s t day of t e s t i n g , the hand was i n P o s i t i o n 1. MVC datum was c o l l e c t e d ; then, f o l l o w i n g a two minute r e s t the i s o m e t r i c f a t i g u e curves were c a l c u l a t e d . The f o l l o w i n g day s i m i l a r procedures were c a r r i e d out f o r P o s i t i o n 2. F o l l o w i n g the p r e t e s t the s u b j e c t s were placed i n t o t h r e e groups a c c o r d i n g to t h e i r MVC at P o s i t i o n 1. Four weaker s u b j e c t s (with s t r e n g t h r a t i n g s below 8.60 kg) were i n a group with four s t r o n g e r s u b j e c t s (strength r a t i n g s above 8.60 kg) t o equate groups with r e s p e c t t o i n i t i a l s t r e n g t h . , A l l t r a i n i n g procedures were c a r r i e d out i n P o s i t i o n 1. Experimental Group 1 (ES) r e c e i v e d e l e c t r i c a l s t i m u l a t i o n 30 as a t r a i n i n g method. The s t i m u l a t i n g pads were pl a c e d on the d o r s a l s i d e of the forearm. r Bather than the use of motor p o i n t c h a r t s , S t i l l w e l l (1968) suggests t h a t o p t i m a l s t i m u l a t i o n i s achieved when the e l e c t r o d e s are placed on the b a s i s of a natomical knowledge. One e l e c t r o d e was p l a c e d over the o r i g i n of the extensor muscle group (proximal end cf the forearm on the v e n t r a l s i d e ) . The other e l e c t r o d e was placed near the musculotendonous j u n c t i o n a t the d i s t a l end of the muscle. To decrease the r e s i s t a n c e of the s k i n the forearm was cleaned then water and Redux paste was spread over the forearm and s t i m u l a t i n g pads. The s t i m u l a t i o n pads were then placed i n the a p p r o p r i a t e p o s i t i o n s and secured t o the arm by e l a s t i c s t r a p s with v e l c r c f a s t e n i n g the ends. As an a c c l i m a t i z a t i o n , the i n t e n s i t y of s t i m u l a t i o n was s l o w l y i n c r e a s e d d u r i n g the f i r s t f i f t e e n seconds. A f t e r t h i s time the i n t e n s i t y of s t i m u l a t i o n was i n c r e a s e d to a l e v e l j u s t below the s u b j e c t ' s p a i n t h r e s h o l d , and continued f o r the remaining 4 .75 min. Each s u b j e c t i n Group 1 was t r a i n e d i n t h i s manner once a day, Monday through F r i d a y f o r twenty s e s s i o n s . 31 The second e x p e r i m e n t a l group TABLE 4:5 FORCE (KG) EXERTED WHILE HAND IN POSITION 2 GROUP PRE MID POST X sd X~ sd X~ sd 10. 19 2.70 12.07 2.05 13.64 3.58 10.78 1.91 12.95 2.29 14.13 2.78 10.49 1.81 13.23 1.88 14.50 2.94 1) ES 2) VI 3) ES + VI PRE M!D POST F!G 4:2 STRENGTH DATA POSITION 2 43 F i g u r e 4:2 i l l u s t r a t e s the improvement tr e n d f o r i s o m e t r i c s t r e n g t h i n P o s i t i o n 2, and Table 4:6 i l l u s t r a t e s the r e s u l t s o f the ANOVA f o r i s o m e t r i c s t r e n g t h i n P o s i t i o n 2. TABLE 4:6 ANOVA FOR STRENGTH DATA AT POSITION 2 SOURCE df MS F p C o n d i t i o n s