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The effects of electrical stimulation on muscular strength and endurance of the extensor muscles of the… Goldsmid, Bruce C 1978

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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 <VI) was t r a i n e d Monday, Wednesday and Friday f o r f o u r weeks using f o u r s e t s o f e i g h t MVCs. A metronome was used i n order t h a t s u b j e c t s could c a r r y out a r e g u l a r cadence. Pea* t e n s i o n cf each MVCs was h e l d f o r two seconds, the r e l a x a t i o n p e r i o d between each c o n t r a c t i o n was f o r a d u r a t i o n of two seconds. One minute cf r e s t was a l l o t t e d between each s e t o f e i g h t MVC. The t h i r d e x perimentel group <ES*VI) r e c e i v e d the same e l e c t r i c a l s t i m u l a t i o n t r a i n i n g program as experimental Group 1. On the Monday, Wednesday and Friday f o l l o w i n g a f i f t e e n minute r e s t p e r i o d , the same s u b j e c t s performed the same i s o m e t r i c t r a i n i n g as Group 2. T h i s t r a i n i n g program a l s o had a d u r a t i o n o f four weeks. MVC and endurance data was c o l l e c t e d p r i o r t o any t r a i n i n g procedures; a f t e r two weeks cf t r a i n i n g , and at the end of the f o u r week t r a i n i n g program. 32 TABLE 3:1 TRAINING SCHEDULE FOB ONE SEEK i 1— 1 — - 3 : 1 3 T I I HON I TUES J WED | THUBS J FBI 1 , j + j H ., .j |GEODP 1 J E.S. | E.S. | E.S. J E.S. J E.S. 1 I • 1 -i -i— -i—• -1 ^ JGBOUP 2 j V.I. } | V.I. | | V.I. J i i + -i -i +" i JGROUP 3 | ES+VI | E.S. | ES+VI | E.S. J ES + VI J i i L _ a 1 . . . n i .. _ J ELECTRICAL STIMULATION - E S VOLUNTARY ISOMETRIC TBAIN1NG - V I S t a t i s t i c a l A n a l y s i s Four separate 3x3 ANCVAS with repeated measures on the second f a c t o r were used to analyse the MVC and endurance data. 1) ANOVA 1 - MVC POSITION 1 2) ANOVA 2 - ENDURANCE POSITION 1 33 3) AN OVA 3 - MVC POSITION 2 **) AN OVA 4 - EN DURANCE POSITION 2 On each s e t o f data f o l l o w i n g t h e f o u r ANOVAS t h r e e s e t s o f c o n t r a s t s , orthogonal to each o t h e r were used t o t e s t f o r the l o c a t i o n o f s i g n i f i c a n c e . TABLE 3:2 ORTHOGONAL CONTRASTS 1 1— ~ s — 1 : ~% I 1 1 I I I i 1 i I j j PRE I MID ] POST I E.S. | 2 i -1 J -1 I I I I 0 I -1 1 + 1 i V.I. | 2 J -1 1 - 1 I j I I I i I I 0 i -1 1 + 1 I i I I I i } — 1 +- 1- - 1 I I 1 1 1 1 1 I 1 1 1 ES+VI J 2 } -1 1 - 1 I i I 1 I I I 1 0 1 - 1 1 + 1 1 I I I I i i I i L 1 ; , 1 34 Chapter 17 RESULTS AKD DISSCUSSION Twenty-four male s u b j e c t s v o l u n t e e r e d to take p a r t i n t h i s study. Subject data i s summarized i n Table 4:1. TABLE 4:1 SUEJECT DATA GBOUP AGE (YEABS) HEIGHT (KG) X sd X sd 1 E l e c t r i c a l S t i m u l a t i o n (ES) 24.60 3.14 76.00 8.58 2 Voluntary I s o m e t r i c (VI) 24.25 2.96 72.75 13.98 3 E l e c t r i c a l S t i m u l a t i o n * 24.62 2.92 82.00 13.18 Vo l u n t a r y I s o m e t r i c (ES+VI) The r e s u l t s c f the i n v e s t i g a t i o n are d i v i d e d i n t o s e c t i o n s r e l a t i n g to each h y p o t h e s i s , the f i r s t s e c t i o n d e a l s with Hypothesis 1, which observes the s t r e n g t h changes of a l l th r e e experimental c o n d i t i o n s over a f o u r week t r a i n i n g p e r i o d . The second s e c t i o n of the d i s c u s s i o n i n t e g r a t e s both Hypothesis 2 and 3, and compares the s t r e n g t h changes of the t h r e e e x p e r i m e n t a l c o n d i t i o n s to cue another. The f i n a l s e c t i o n of the d i s c u s s i o n d e a l s with the endurance changes of a l l t h r e e experimental c o n d i t i o n s . SECTION 1 P o s i t i o n J. Table 4:2 r e v e a l s the c e l l means f o r i s o m e t r i c s t r e n g t h f o r the t h r e e experimental groups t e s t e d i n P o s i t i o n 1, F i g u r e 4:1 i l l u s t r a t e s the improvement t r 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 1 , and Table 4:3 i l l u s t r a t e s the r e s u l t s of the 3x3 ANOVA f o r the s t r e n g t h data f o r s u b j e c t s i n P o s i t i o n 1. TABLE 4:2 FORCE (KG) EXERTED WHILE HAND IN POSITION 1 GROUP PRE MID POST X sd X sd X sd 1) ES 8.31 1.72 11.57 2.06 11.79 1.85 2) VI 9.04 1.83 12.05 3.03 12.58 1.80 3) ES+VI 9.02 2. 32 12.39 2.34 13.95 2.24 15 FIG 4;1 S T R E N G T H DATA POSITION 1 37 TABLE 4:3 ANOVA FOB STRENGTH DATA AT POSITION 1 SOURCE df MS C o n d i t i o n s (C) 2 9.04 0.80 .46 SwC 21 11.27 T r i a l s <Tr) 2 106.88 74.76 < .01 CxTr 4 1.61 1.12 .35 SwCxTr 42 1.41 The ANCVA r e v e a l s t h a t both the C o n d i t i o n s e f f e c t and C o n d i t i o n s x T r i a l s e f f e c t are not s i g n i f i c a n t , thus i t must be concluded t h a t the three groups e x h i b i t e d e q u i v a l e n t s t r e n g t h g a i n s over the three t e s t i n g p e r i o d s . Very high s i g n i f i c a n c e was observed i n the T r i a l s e f f e c t , thus, i t can be s t a t e d with c o n f i d e n c e t h a t a s i g n i f i c a n t s t r e n g t h i n c r e a s e occurs between the Pre-Post s t r e n g t h measures i n one pr more o f the t h r e e t r a i n i n g c o n d i t i o n s . To t e s t f o r the l o c a t i o n of s i g n i f i c a n t t r i a l s e f f e c t , three s e t s o f two preplanned c o n t r a s t s , orthogonal t o each 38 o t h e r , were used, f h i s allowed the r e s e a r c h e r t o a s c e r t a i n whether, the s i g n i f i c a n c e cccured between the Pre and Eid+Post or Mid-Post t r a i n i n g p e r i o d s . The r e s u l t s are i l l u s t r a t e d on Table 4:4. ; TABLE 4:4 PREPLANNED CONTRASTS ON TB.IALS EFFECT CONDITIONS PRE VS M i l + POST MID VS POST F p F p 63.60 < .01 1.42 NS 59.63 < .01 0.79 NS 96.46 < .01 6.76 < .05 ES VI ES + VI C r i t F .05=4.07 C r i t I .01=7.27 Table 4:4 r e v e a l s that i n a l l three experimental c o n d i t i o n s the most 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 occur between the Pre t e s t and the Mid+Post. During the Mid-Post p e r i o d the only s i g n i f i c a n t s t r e n g t h g a i n i s seen i n the ES+VI group, and both the ES and the VI groups show no s i g n i f i c a n t s t r e n g t h i n c r e a s e s d u r i n g the f i n a l two week p e r i o d . Various authors {Hettinger and {fuller,19.53; Walters, 1953; and Boilleau,1962) have a l l i l l u s t r a t e d t h a t s i g n i f i c a n t s t r e n g t h i n c r e a s e s occur using 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 as a t r a i n i n g method. The VI group i n t h i s study f u r t h e r exemplify t h i s p o i n t . Although v o l u n t a r y i s o m e t r i c t r a i n i n g has been used as a s t r e n g t h t r a i n i n g technique s u c c e s s f u l l y , 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 method of i n c r e a s i n g s t r e n g t h has l o n g been a g u e s t i o n i n the eyes of v a r i o u s r e s e a r c h e r s . S t i l l w e l l (1967) had some doubt whether muscle c o n t r a c t i o n s caused by f a r a d i c s t i m u l a t i o n c o u l d produce s t r e n g t h i n c r e a s e s . T h i s study suggests 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 y i e l d s adequate contractions,when the hand i s l o c k e d i n an i s o m e t r i c p o s i t i o n , to produce s i g n i f i c a n t s t r e n g t h g a i n s . Goldberg (1974) f e e l s t h a t the c o n t r a c t i l e work i s the major f a c t o r which c o n t r o l s AIB uptake,and t h a t the cause f o r s t r e n g t h i n c r e a s e s i s not c o n t r o l l e d by a n e u r a l event. The f i n d i n g s i n t h i s study support Goldberg's theory; p o s s i b l y the same bi o c h e m i c a l consequence i n the VI and ES groups are c a u s i n g 4 0 the s t r e n g t h i n c r e a s e s r e g a r d l e s s o f the form of e l e c t r i c a l s t i m u l a t i o n , be i t i n t e r n a l or e x t e r n a l . Both the ES and VI experimental groups e l i c i t d i f f e r e n t g u a n t i t i e s of c o n t r a c t i l i t y and both are i n i t i a t e d by d i f f e r e n t forms o f e l e c t r i c a l impulse i n order t o cause muscular c o n t r a c t i o n . The VI c o n t r a c t i o n s are o r i g i n a t e d by normal n e u r a l c o n t r o l from the CNS. , The ES c o n t r a c t i o n s o r i g i n a t e from an e n t i r e l y d i f f e r e n t method. I n d i r e c t s t i m u l a t i o n from e l e c t r o d e s permeates the muscle, and the sarcomeres which are s t i m u l a t e d c o n t r a c t i n a t e t a n i c manner., as mentioned above the ES+VI group was the onl y group which 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 gains i n the Mid-Post t e s t i n g p e r i o d s . T h i s data i l l u s t r a t e s t h a t the s t r e n g t h i n c r e a s e s have a l e v e l i n g o f f e f f e c t when the same t r a i n i n g method i s adm i n i s t e r e d over a fo u r week p e r i o d . In the ES and VI group the same c o n t r a c t i l e s t i m u l u s e x i s t e d w i t h i n each group s e p a r a t e l y , yet onl y d u r i n g the f i r s t two weeks d i d any s i g n i f i c a n t s t r e n g t h occur. as s t r e n g t h i n c r e a s e s i t i s e v i d e n t t h a t more c o n t r a c t i l e work i s r e q u i r e d i n order t h a t s i g n i f i c a n t 41 s t r e n g t h i n c r e a s e s continue to occur. „• The ES+VX group continued to have adeguate c o n t r a c t i l e s t i m u l u s i n order t h a t s t r e n g t h gains continued to cccur., The r a t i o n a l e behind t h i s phenomena i s d i s c u s s e d i n S e c t i o n 2. P o s i t i o n 2 Table 4:5 r e v e a l s the c e l l means f o r i s o m e t r i c s t r e n g t h f o r the t h r e e experimental groups t e s t e d i n P o s i t i o n 2. The s t r e n g t h r e s u l t s f o r P o s i t i o n 2 are s i m i l a r to P o s i t i o n 1 with the e x c e p t i o n of the Mid-Post or t h o g o n a l contrast.> 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 <C) 2 4.18 0.26 .77 SwC 21 15.83 T r i a l s (TR) 2 79.69 52.93 < .01 CxTr 4 0.46 0.30 .87 SwCxTr 42 1.51 The ANOVA t a b l e r e v e a l s t h a t both the C o n d i t i o n s e f f e c t and the C o n d i t i o n s x T r i a l s e f f e c t are not s i g n i f i c a n t . , Very high s i g n i f i c a n c e was observed i n the T r i a l s e f f e c t , thus w i t h i n the Pre-Post t r i a l s a s i g n i f i c a n t s t r e n g t h t r a i n i n g e f f e c t takes place w i t h i n one or more of the t h r e e t r a i n i n g c o n d i t i o n s i n P o s i t i o n 2. Two s e t s o f three preplanned c o n t r a s t s were c a l c u l a t e d 44 s i m i l a r t o the method used f o r P o s i t i o n 1. The r e s u l t s are summarized on Table 4:7. TABLE 4:7 PREPLANNED CONTRASTS CN TBIALS EFFECT CONDITIONS PEE VS MID+POST HID ¥S POST F p F p 37.91 < .01 6.53 < .05 40.49 < .01 3.81 NS 80.34 < .01 4.27 < .05 C r i t F .05=4.07 C r i t F .01=7.27 Table 4:7 i l l u s t r a t e s t h a t the most s i g n i f i c a n t s t r e n g t h i n c r e a s e s f o r a l l three t r a i n i n g c o n d i t i o n s o c c u r r e d between the Pre t e s t and the Hid • Post t e s t . During the second two week pe r i o d only the ES+VI and t h e VI group had s i g n i f i c a n t s t r e n g t h g a i n s . The VI group d i d net y i e l d s i g n i f i c a n t s t r e n g t h gains d u r i n g the Mid-Post t r a i n i n g 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 gains are seen t o occur not o n l y a t the muscle l e n g t h at which i t was t r a i n e d but a l s o a t a ES VI ES+VI 45 d i f f e r e n t muscle l e n g t h . Table 4 : 6 . i l l u s t r a t e s t h a t s i g n i f i c a n t s t r e n g t h i n c r e a s e s occur i n P o s i t i o n 2, and Table 4:7 i l l u s t r a t e t h a t a l l t h r e e experimental c o n d i t i o n s e x p e r i e n c e s t r e n g t h g a i n s , with the most s i g n i f i c a n t gains between the Pre t e s t and Mid+Post. These f i n d i n g s support the work of Basch et a l . , {1961) and Beyers (1967) t h a t v o l u n t a r y i s c m e t r i c t r a i n i n g i n c r e a s e s s t r e n g t h at a muscle l e n g t h other than which i t was t r a i n e d . T h i s study f u r t h e r i l l u s t r a t e s t h a t s t r e n g t h gains occur w i t h i n the ES and ES+VI groups at the muscle l e n g t h t r a i n e d and at a muscle l e n g t h which was not trained.., As mentioned i n Chapter 2 the i n t e n s i t y and d u r a t i o n o f the working muscle seem t o be the c o n t r o l l i n g f a c t o r s when attempting to 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 . In a l l three experimental c o n d i t i o n s d u r i n g the Mid-Post t r a i n i n g s e s s i o n s s t r e n g t h gains are not as e v i d e n t as the i n the Pre and Mid+Post p e r i o d . In P o s i t i o n 1 only the ES+VI Group y i e l d a s i g n i f i c a n t s t r e n g t h i n c r e a s e . In P o s i t i o n 2 both the ES Group and the ES+VI Group have s i g n i f i c a n t s t r e n g t h g a i n s d u r i n g the Mid-Post p e r i o d . The s i g n i f i c a n t s t r e n g t h i n c r e a s e i n the ES+VI Group c o u l d be e x p l a i n e d by the a d d i t i o n of c o n t r a c t i l e work r e q u i r e d when using both techniques* There seems to be no r a t i o n a l e x p l a n a t i o n why i n P o s i t i o n 1 the ES Group y i e l d s no s i g n i f i c a n t s t r e n g t h i n c r e a s e s yet i n P o s i t i o n 2 a s i g n i f i c a n t s t r e n g t h g a i n i s found i n the Mid-Post t e s t i n g p e r i o d s . The f i n d i n g s i n t h i s study support Hypothesis 1. S i g n i f i c a n t s t r e n g t h gains occur i n a l l three experimental c o n d i t i o n s a f t e r a four week t r a i n i n g p e r i o d at both muscle l e n g t h s t e s t e d . , SECTION 2 Table 4:8 r e v e a l s the mean i n c r e a s e s between the Pre-Post p e r i o d f o r i s c m e t r i c s t r e n g t h at bcth p o s i t i o n s t e s t e d . TABLE 4:8 MEAN INCREASES BETWEEN PEE-POST PERIOD {KG) GROUP POSITION 1 POSITION 2 ES 3.48 3.45 VI 3. 54 3. 35 ES+VI 4.93 4.01 The summation of mean s t r e n g t h i n c r e a s e s f o r the ES and VI Groups i n P o s i t i o n 1 i s 7.02 kg. The mean i n c r e a s e f o r the ES+VI Group i s only 4.93 kg. thus. Hypothesis 3 i s supported, as the summation o f the mean i n c r e a s e s i n s t r e n g t h f o r the ES and VI Groups i s l e s s than the ES+VI Group. S i m i l a r r e s u l t s a r e found with the hand i n P o s i t i o n 2. The summation of the ES and VI Groups i s 6.80 kg. T h i s i s g r e a t e r 48 than when both techniques are admi n i s t e r e d to the same s u b j e c t s . The ES+VI Group,although performing the work of both the ES and VI Groups s e p a r a t e l y , d i d not y i e l d t h e i n c r e a s e o f the s t r e n g t h which were a d d i t i v e o f the two groups s e p a r a t e l y . S t r e n g t h i n c r e a s e s w i t h i n a muscle do not i n c r e a s e l i n e a r l y , and can be e x p l a i n e d by a s t i m u l u s response curve. The s t i m u l u s i s the c o n t r a c t i l e i n t e n s i t y r e q u i r e d by t h e muscles, and the response i s the i n c r e a s e i n s t r e n g t h . T h i s study i l l u s t r a t e s t h a t t h e sti m u l u s - r e s p o n s e i s p o s i t i v e l y a c c e l e r a t i n g and t h a t much more s t i m u l u s or c o n t r a c t i l e f o r c e i n p r o p o r t i o n t o the f i r s t two weeks t r a i n i n g s e s s i o n i s r e q u i r e d before s i m i l a r s t r e n g t h i n c r e a s e s occur. &NGVA Tables 4:3 and 4:6 r e v e a l t h a t the C o n d i t i o n s X T r i a l s e f f e c t i s not s i g n i f i c a n t ; t h e r e f o r e , there i s no s i g n i f i c a n t d i f f e r e n c e among s t r e n g t h i n c r e a s e s of the th r e e groups over time, thus s u p p o r t i n g Hypothesis 2. Goldberg (1974) suggests t h a t the st i m u l u s f o r i n c r e a s i n g s t r e n g t h i s dependent on the i n t e n s i t y and d u r a t i o n of muscle c o n t r a c t i o n . The s u b j e c t s i n the ES+VI Group r e q u i r e more c o n t r a c t i l e a c t i v i t y i n order to c a r r y - out t h e i r t r a i n i n g program than e i t h e r s u b j e c t s i n the ES or VI Groups. The augmented i n t e n s i t y and d u r a t i o n of t r a i n i n g w i t h i n the ES+VI Group does not seem t c be s u f f i c i e n t to y i e l d s i g n i f i c a n t s t r e n g t h i n c r e a s e s over the other two t r a i n i n g techniques. Although a l l t h r e e groups s i g n i f i c a n t l y i n c r e a s e d i n i s o m e t r i c s t r e n g t h , due to the nature of t h i s study i t cannot be concluded that s t r e n g t h gains are due to an i n c r e a s e d d e i n h i b i t i o n by g o l g i tender as Morehouse suggests; nor can i t be concluded t h a t i t i s caused by an i n c r e a s e i n p r o t e i n uptake i n the muscle as suggested by Goldberg (1974) although they c o u l d be r e l a t e d t o the cause. SECTION 3 T a b l e s 4:9 and 4:10 r e v e a l the c e l l means f o r i s o m e t r i c endurance i n a l l t h r e e experimental c o n d i t i o n s with the hand i n P o s i t i o n s 1 and 2 r e s p e c t i v l y . 50 TABLE 4:9 ENDURANCE CELL MEANS POSITION 1 {SECS TO 65% OF MAX) GROUP PEE MID POST X sd X sd X sd 1} ES 28.70 10.25 24.05 12.58 29.30 16.92 2) VI 29.90 12.57 22. 32 8.31 28.2 1 12.54 3) ES+VI 33.57 16.92 31.70 15.60 32.98 12.64 TAELE 4:10 ENDURANCE CELL MEANS POSITION 2 (SECS TO 65% OF MAX) GBOUP PEE MID POST X sd X sd X sd 1) ES 32.72 10.51 20.87 10.24 32.02 15.07 2) VI 27.32 8. 35 26.94 8.39 24.73 1-1.70 3) ES + VI 22.71 7.29 26.50 9.26 27.55 9.82 f i g u r e 4:3 and 4:4 i l l u s t r a t e t h e t r e n d f o r i s o m e t r i c endurance i n P o s i t i o n 1 and P o s i t i o n 2 r e s p e c t i v l v . Table 4:11 and 4:12 r e v e a l the r e s u l t s of t h e ANOVA f o r i s o m e t r i c endurance 51 with the hand i n P o s i t i o n 1 and P o s i t i o n 2. TABLE 4:11 ANOVA f OR ENDUE JINCE DATA AT POSITION 1 SOURCE df ES f P C o n d i t i o n s <C) 2 9.04 0.80 .46 SwC 21 11.27 T r i a l s (Tr) 2 158.10 1.48 . 23 CxTr 4 20.91 0.20 .93 SwCxTr 42 106.36 The ANOVA t a b l e s f o r i s o m e t r i c endurance i n P o s i t i o n 1 and P o s i t i o n 2 r e v e a l t h a t there i s no s i g n i f i c a n t d i f f e r e n c e i n i s c m e t r i c endurance between the v a r i o u s C o n d i t i o n s (C) c r T r i a l s (T) i n t h i s study. I t a l s c i l l u s t r a t e s that no s i g n i f i c a n t i n t e r a c t i o n (CxTr) e x i s t s i n e i t h e r P o s i t i o n 1 or P o s i t i o n 2. These r e s u l t s support Hypothesis 4. H G 4:4 ENDURANCE DATA POSIT ION 2 54 TABLE 4:12 ANOVA FOR ENDUR1NCE DATA AT POSITION 2 SOURCE df MS f P Conditions CC) 2 77.04 0.57 .57 SwC 21 134.33 T r i a l s (Tr) 2 56.60 0.62 .54 CxTr 4 174.02 1.89 .12 SwCxTr 42 90.?4 The VI group contracted t h e i r muscles maximally and the t o t a l time of contraction «as only 96 seconds for each t r a i n i n g period. The ES group had only 2.5 minutes of contracting time, and the high freguency of stimulation pronably stimulated a l l the motor units and fibres within the muscle. The duration of both t r a i n i n g methods are short and possibly could be one reason for the non s i g n i f i c a n t endurance findings. The measurement of endurance i s a r e l a t i v e measurement, taken at 65% cf the MVC at each tes t i n g period, thus the endurance time must a l t e r with respect to each new MVC i n order to a l t e r endurance. The e l e c t r i c a l s t i m u l a t i o n permeating the sarcomeres f a c i l i t a t e a t e t a n i c c o n t r a c t i o n thus r e c r u i t i n g f a s t t w i t c h f i b e r s , and high t e n s i o n development i s predominant, T h i s type o f c o n t r a c t i o n i s not conducive to endurance t r a i n i n g and one should not expect t o observe endurance i n c r e a s e s . The slow t w i t c h f i b r e s although s t i m u l a t e d would y i e l d lew t e n s i o n and f o r a s h o r t p e r i o d of time (2.5 min), and t h i s t r a i n i n g regime i s not adequate to y i e l d endurance a l t e r a t i o n s . I f the d u r a t i o n of s t i m u l a t i o n had been lo n g e r and the i n t e n s i t y lower p o s s i b l y the ' s i z e 1 p r i n c i p l e c f mctor r e c r u i t s e n t would have been more predominant; thus, slow t w i t c h f i b r e s would have been t r a i n e d and endurance r a t h e r than s t r e n g t h changes would have been observed. 56 CHAPTER V SUM8ABY AND CONCLUSIONS Summary This study took twenty-four aale s u b j e c t s and d i v i d e d them i n t o t h r e e groups c f e i g h t j a t t e m p t i n g to equate groups with r e s p e c t to i n i t i a l s t r e n g t h of the extensor muscles of the hand. For a four week t r a i n i n g p e r i o d each group i s c m e t r i c a l l y t r a i n e d the extensor muscles of t h e i r hand each using a d i f f e r e n t t r a i n i n g technique. Group 1 r e c e i v e d i n d i r e c t e l e c t r i c a l s t i m u l a t i o n on the d o r s a l s u r f a c e of t h e i r forearm f o r a f i v e minute d u r a t i o n . Group 2 t r a i n e d u s i n g four s e t s o f e i g h t MVCs and each c o n t r a c t i o n was f o r a d u r a t i o n o f two seconds. T h i s t r a i n i n g was performed t h r e e times a week. Group three performed the t r a i n i n g procedures o f both Group 1 and 2. The s t r e n g t h and endurance of the muscle was tested at the muscle l e n g t h t r a i n e d ( P o s i t i o n 1) as w e l l at muscle l e n g t h s a t which they were not t r a i n e d ( P o s i t i o n 2)., I t was hypothesized that a l l three t r a i n i n g c o n d i t i o n s would y i e l d s i g n i f i c a n t strength g a i n s , y e t s t r e n g t h g a i n s y i e l d e d i n the ES and VI groups would not be a d d i t i v e with r e s p e c t t o the ES+VI group. I t was a l s o hypothesized, t h a t the endurance of the extensor muscles of the hand would not s i g n i f i c a n t l y i n c r e a s e . S i g n i f i c a n t s t r e n g t h gains occur ed. i n a l l th r e e groups d u r i n g the f i r s t two weeks of t r a i n i n g i n P o s i t i o n 1 and P o s i t i o n 2. During the second two week t r a i n i n g p e r i o d only 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; where as 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 gains. I t was i l l u s t r a t e d t h a t the 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 are 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 tested,and t h a t one method of t r a i n i n g was not s i g n i f i c a n t l y b e t t e r than another. During the f o u r week t r a i n i n g p e r i o d the mean endurance o f the muscles d i d not a l t e r s i g n i f i c a n t l y i n a l l of the th r e e groups. 58 C o n c l u s i o n s 1) E l e c t r i c a l s t i m u l a t i o n , used i n the method o f t h i s experiment i s a good method of i n c r e a s i n g i s c m e t r i c s t r e n g t h of the extensor muscles of the hand. 2) E l e c t r i c a l s t i m u l a t i o n used as a form of s t r e n g t h t r a i n i n g i s not a b e t t e r form o f s t r e n g t h t r a i n i n g than voluntary i s o m e t r i c t r a i n i n g as used i n t h i s experiment. 3) The use of v o l u n t a r y i s c m e t r i c t r a i n i n g + e l e c t r i c a l s t i m u l a t i o n does not y i e l d a d d i t i v e s t r e n g t h gains of the two t r a i n i n g techniques when used s e p a r a t e l y . 4) ES,VI,and ES+VI t r a i n i n g as used i n t h i s experiment have no s i g n i f i c a n t e f f e c t s on the endurance of the extensor muscles o f the hand. Suggestions For F u r t h e r Research This study was designed to observe the changes i n s t r e n g t h o f the extensor muscles of the hand using ES,VI ABC ES+VI t r a i n i n g . Although s t r e n g t h changes o c c u r r e d only h y p o t h e t i c a l p o s t u l a t i o n s can be made as to the morphological a l t e r a t i o n s w i t h i n the muscles t r a i n e d . The next q u e s t i o n to be answered i n t h i s work i s to what ext e n t d i d the muscle change m o r p h o l o g i c a l l y due to the v a r i o u s t r a i n i n g procedures? The measurement of nonmetabclized amino a c i d AIB would q u a n t i f y the e x t e n t o f the p r o t e i n uptake w i t h i n the muscle, and then c o n c l u s i o n s as to the e f f i c i e n c y o f each t r a i n i n g regime c o u l d be made. 60 BEFERENCES A r v i l , A. 1967. R e l a t i o n s h i p s Between the E f f e c t s of Muscle C o n t r a c t i o n and I n s u l i n on the Metabolism of the I s o l a t e d Levator Ani Muscle Of the Bat., Acta E n d o c r i n o l . 56, Suppl. 122:27-41. Astrand, P.O. and Eo d a h l , K. , 1S74. Textbook of Sork P h y s i o l o g y . M c g r a w - h i l l , New York. B o i l e a u , R.A. 1962. Masters T h e s i s , Univ. of Maryland, C o l l e g e Park, Maryland. , C a l d w e l l , L.S. et a l . 1974. A Proposed Standard Procedure f o r S t a t i c Muscle Strength T e s t i n g . Am. I n d u s t r i a l Hygiene M s . Jj, 4:201-6. C l a r k , D.H. 1973. Adaptations i n Strength and Muscular Endurance R e s u l t i n g from E x e r c i s e . i n E x e r c i s e And Sp o r t Science Reviews. Ed By J . H. , Hilmore. 1: 73-102. 61 d e V r i e s , H.A., 1968. Ph y s i o l o g y of E x e r c i s e . R.M.C. Brown, Dubugue, Iowa. Goldberg, A.L. e t a l . 1976. 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B r i t . J± Phys. Hfd.. 15:249., L u i , C . l . , and Lemey, F,H. 1947. E f f e c t s of Surging C u r r e n t of low Freguency i n Man cn atrophy of Denervated Muscles. 3 ^ Neruj. Ment t D i s . , 305:571. Meyers, C.B. 1967. E f f e c t s of Tso I s o m e t r i c Routines on S t r e n g t h and Endurance i n E x e r c i s e d and flonexercised Arms. E e s i ; Quart 38: 430-440. Meyers, C.B.,and Ohmacht, F.I.,- 1963, I s o m e t r i c T r a i n i n g . Proc. C o l l . , Physj, Educ. Ass. 66:113-117., Morehouse, I.E., and M i l l e r , A.T. 1971. E x e r c i s e . C V . Mosey Co. St L o u i s . Physiology of 64 Morehouse, I.E. 1965. Neurophysiology of S t r e n g t h . Proceedings Of The F i r s t I n t e r n a t i o n a l Congress of Sgprt. Nowakowska, A. 1962. I n f l u e n c e of E x p e r i m e r t a l T r a i n i n g by E l e c t r i c C u r r e n t S t i m u l a t i o n of S k e l e t a l Muscle. A c t a . g D Y . § i g i g g i c § A P o l c n i c a . 12:32-38. Osbourne, S.L. 1951. Re t a r d a t i o n of Atrophy i n Man by E l e c t r i c a l S t i m u l a t i o n cf Muscles. Arch. P h y s & Med. 32:523. Osbourne, S.L., And Kosman, A.J. e t . a l . 1950. A n t e r i o r P o l i o m e y e l i t i s : E a r l y and Late E l e c t r i c a l S t i m u l a t i o n o f A f f e c t e d Muscles,, E r i t . ~J±, Phys. MjuLs. 13:97. Peckham, P.H,, e t a l , 1976. A l t e r a t i o n i n Force and F a t i g a b i l i t y c f S k e l e t a l Muscleln C u a d r i p e l e g i c Humans Foll o w i n g E x e r c i s e InducedBy Chronic E l e c t r i c a l S t i l u l a t i o n . C l i n i c a l Orthopaedics and B e l a t e d Research. 114:326-334. 65 Rasch, P.J., and Morehouse, L. £. 1961. E f f e c t s o f S t a t i c and Dynamic E x e r c i s e on Muscular Strength and Hypertrophy. J iJE£ii P h y s i o l . 11; 18. Rasch, P.J., et a l . 1961. The E f f e c t s of I s c m e t r i c E x e r c i s e Upon the Strength of an t a g o n i s t Muscles., I n t e r n . Angew. P h y s i o l . 19:18. S h a f f e r , D.V., e t a l . , 1954. The I n f l u e n c e of E l e c t r i c a l S t i m u l a t i o n on the Course of Denervation atrophy. Arch. Ph ysj. Med.. 35:491. Solandt, D.Y., et a l . 1943. 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 Atrophy of Denervated S k e l e t a l Muscle. P h y c h i a t r 49:802. S t i l l w e l l , K.G. 1967. C l i n i c a l E l e c t r i c a l S t i m u l a t i o n i n The r a p e u t i c E l e c t r i c i t y and U l t r a v i o l e t R a d i a t i o n . E l i z a b e t h L i g h t 2nd E d i t i o n . Newhaven, Conneticut. :105-155. 66 Thorn, fl. 1957. Treatment cf P a r a l y s i s with E x p o n e n t i a l l y P r o g r e s s i v e C u r r e n t s . g r i t . J . Phy_s. ,. Med A , 20:49.)s Sakim, K.G., and Krusen, F.H. 1955. The I n f l u e n c e o f E l e c t r i c a l S t i m u l a t i o n on the Hork Output and Endurance of Denervated S k e l e t a l Muscle. Arch^ Phys.. Med. . 36:370.)s w a i t e r s , C.E. , e t a l . (1960). E f f e c t s of Short Bouts o f I s c m e t r i c and I s o t o n i c C o n t r a c t i o n s on Muscular Strength and Endurance. Am± J . Phys. Med^. 39:131-141. 67 APPENDICIES J i l DATA St r e n g t h (kg) P o s i t i o n 1 Endurance (sec) P o s i t i o n 1 Sub # Pre Mid Post Pre Mid Post 01 6.82 10.38 11.23 42. 9 14.9 19.8 02 7.38 9. 19 8. 99 39.0 62.7 51.0 03 6.25 9.31 10.72 24.3 12.3 30.0 04 6.66 13.44 12.74 18.3 28.8 43.8 05 9. 50 10.72 10.S8 21.3 15.9 35.4 06 9.77 11. 64 11. 97 15.6 8.7 10.8 07 10.80 14.98 15.40 36.9 27.0 26.7 08 9.37 12.91 12.33 3 1. 2 22.5 16.8 09 6. 30 11.78 11.22 4 9.8 14. 1 44.4 10 8.60 9.39 12.79 32.7 35.4 19.2 11 8.24 10.69 12.26 17.7 22.5 20. 1 12 7. 30 13.21 11. 11 18.0 12.0 26.7 13 9. 16 8.46 11.11 18.6 28*8 12.0 14 11.53 16.28 13.96 36. 9 28.5 33.9 15 11.26 16.47 16.32 22.2 22.5 22. 2 16 10. 00 10.11 11.87 43. 2 19.7 47.1 17 6. 47 12.46 13.33 30.3 21.6 17.6 18 7.81 10,65 13. 67 35.7 50.7 33.9 19 6.89 8.92 10.30 65.1 55.5 55.8 20 6.82 10.34 11.26 10.2 15.9 26.0 21 11. 83 16.01 15.55 45.0 29.4 24.3 22 10.75 14.60 15.36 20.7 42.0 42.3 23 12.06 13.37 15.55 39.0 19.2 30.6 24 9.54 12.79 16.59 22. 5 19.2 13.2 68 BAB DATA Stre n g t h <kg) P o s i t i c e 2 Endurance (sec) P o s i t i o n 2 Sun # Pre Mid Post Pre Mid Post 01 8. 53 10.38 12. 56 36. 6 35.7 33.0 02 7.05 10.03 10.77 53. 1 i i . o 21.0 03 6. 84 10.88 13.79 20.1 36.9 21.0 04 10. 26 13.86 13.86 30.3 21.6 30.6 05 11. 54 11.95 15.09 34.5 34.2 25.2 06 10.23 11.45 12. 18 37.8 15.2 9.3 07 14.78 15.86 16.62 27.6 32.4 19.5 08 12. 26 12. 56 14. 25 21. 6 21.3 21.9 09 8. 6 3 9.35 12.84 17.7 40.5 19.2 10 11.38 13.67 15. 63 38.4 27,3 16.2 11 9. 19 11.34 11. 22 35.1 12.6 39.0 12 9. 44 11.49 13.52 9.9 25.2 27.9 13 14.42 12.33 12.72 18.6 20.7 8.3 14 11.87 14. 17 15. 70 19.0 30.0 23.4 15 12. 33 16.70 15. 85 14.7 25.2 23.7 16 8. 98 14.59 14.63 14. 4 33.9 41.7 17 9. 80 13.03 15.17 25.5 13.4 39.9 18 8. 17 10.65 14.36 48.0 30.0 36.3 19 8. 96 10.15 10.38 52.2 42.3 20.7 20 8.83 11.11 10.72 10.0 5.4 23. 1 21 15. 63 17.62 19.40 4 3.5 23. 3 22.8 22 10. 49 11.87 14.09 29. 4 20.7 32. 8 23 15.32 16.24 16.38 3 1 . 5 28.2 17.9 24 10.76 15. 17 15.47 15.9 14.7 11,7 

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