UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Mechanical energy variations in rowing Martindale, Walter Olsen 1982

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Notice for Google Chrome users:
If you are having trouble viewing or searching the PDF with Google Chrome, please download it here instead.

Item Metadata

Download

Media
831-UBC_1983_A7_5 M37.pdf [ 3.16MB ]
Metadata
JSON: 831-1.0077390.json
JSON-LD: 831-1.0077390-ld.json
RDF/XML (Pretty): 831-1.0077390-rdf.xml
RDF/JSON: 831-1.0077390-rdf.json
Turtle: 831-1.0077390-turtle.txt
N-Triples: 831-1.0077390-rdf-ntriples.txt
Original Record: 831-1.0077390-source.json
Full Text
831-1.0077390-fulltext.txt
Citation
831-1.0077390.ris

Full Text

MECHANICAL ENERGY VARIATIONS IN ROWING by WALTER OLSEN MARTINDALE B. P. E. A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF PHYSICAL EDUCATION i n THE FACULTY OF GRADUATE STUDIES S c h o o l Of P h y s i c a l E d u c a t i o n And R e c r e a t i o n We ac c e p t t h i s t h e s i s as c o n f o r m i n g t o the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA December 1982 © W a l t e r O l s e n M a r t i n d a l e , 1982 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the r e q u i r e m e n t s f o r an advanced degree a t the U n i v e r s i t y of B r i t i s h C o l u m b i a , I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . 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 of t h i s t h e s i s f o r s c h o l a r l y p urposes may be g r a n t e d by the Head of my Department or by h i s or her r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g or p u b l i c a t i o n of 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 t h o u t my w r i t t e n p e r m i s s i o n . Department of P h y s i c a l Education,1,December,1982 The U n i v e r s i t y of B r i t i s h Columbia 2075 Wesbrook P l a c e Vancouver, Canada V6T 1W5 Date: i i A b s t r a c t The purpose of t h i s s tudy was t o q u a n t i f y and c o n t r a s t the i n s t a n t a n e o u s segmental and t o t a l body energy p a t t e r n s of rowing a s i n g l e s c u l l s r a c i n g s h e l l w i t h rowing a G j e s s i n g (Norway) rowing ergometer, and t o c o n t r a s t energy s a v i n g s t h r o u g h exchanges of m e c h a n i c a l energy among segments and c o n v e r s i o n s of energy w i t h i n segments. Four s c u l l e r s , two male and two female, were f i l m e d a t t h r e e s t r o k e r a t e s w h i l e rowing on a G j e s s i n g rowing ergometer (RE), the RE mounted on a wheeled c a r t , and rowing i n s i n g l e s c u l l s r a c i n g s h e l l s . D i g i t i z e d c o o r d i n a t e s of j o i n t markers were combined w i t h e s t i m a t e d body segment i n e r t i a l p a r a m e t e r s , and e v a l u a t e d w i t h l i n k - s e g m e n t methods a f t e r d i g i t a l f i l t e r i n g t o remove d i g i t i z a t i o n n o i s e . M e c h a n i c a l energy and i n t e r n a l work a n a l y s i s a l l o w e d c a l c u l a t i o n of energy s a v i n g s due t o exchange and i n t e r c o n v e r s i o n of segmental energy. The i n t e r n a l work was l e a s t i n the wheeled RE and g r e a t e s t i n the b o a t . S a v i n g of energy t h r o u g h exchange was g r e a t e s t i n the b o a t , and l e a s t i n the s t a t i o n a r y RE. S a v i n g of energy t h r o u g h i n t e r c o n v e r s i o n was g r e a t e s t i n the wheeled RE. The i n t e r c o n v e r s i o n s ( e x p r e s s e d as a p e r c e n t a g e of t o t a l work) were l o w e r , and q u i t e s i m i l a r f o r both the boat and the s t a t i o n a r y RE. S i m i l a r i t y of energy s a v i n g s c o r e s between the boat and the wheeled RE a l l o w the c o n c l u s i o n t h a t rowing ergometer t e s t i n g might p e r m i t a t h l e t e s t o work a t s t r o k e r a t e s more s i m i l a r t o r a c i n g l e v e l s . i i i T a b l e of C o n t e n t s A b s t r a c t i i L i s t of T a b l e s i v L i s t of F i g u r e s y Acknowledgements v i I n t r o d u c t i o n 1 Purpose 3 Methods 4 S u b j e c t s 4 P r o c e d u r e s 4 M a r k e r s 5 Rowing S e s s i o n 5 Ergometer S e s s i o n s 6 Data C o l l e c t i o n And A n a l y s i s 6 Segmental Energy 8 T o t a l Body Energy 8 I n t e r n a l Work 9 R e s u l t s And D i s c u s s i o n 13 Cinematography 13 Boat T r i a l s 13 Ergometer T r i a l s 13 I n t e r n a l Work 16 Energy Exchange And I n t e r c o n v e r s i o n 23 Average D r i v e Power 29 C o n c l u s i o n s 32 Recommendations 32 R e f e r e n c e s 34 APPENDIX 1 - DEFINITIONS 36 Rowing Terms 36 Energy A n a l y s i s Terms 37 APPENDIX 2 - SYMBOLS USED IN THE PAPER 40 APPENDIX 3 - ENERGY PLOTS OF SUBJECTS 2, 3, AND 4 41 APPENDIX 4 - REVIEW OF LITERATURE 45 Anthropometry 45 Energy And Work 50 Mechanics And Rowing 56 BIBLIOGRAPHY 62 i v L i s t of T a b l e s 1. B a s i c S u b j e c t I n f o r m a t i o n 4 2. I n t e r n a l Work For S c u l l i n g T r i a l s 17 3. I n t e r n a l Work For Wheeled Ergometer T r i a l s 18 4. I n t e r n a l Work For S t a t i o n a r y Ergometer T r i a l s 19 5. Power, S t r o k e R a t e , And V e l o c i t y , S c u l l i n g T r i a l s ....25 V L i s t of F i g u r e s IA. D r i v e Phase Of Rowing A S t a t i o n a r y Ergometer 15 IB. D r i v e Phase Of Rowing A Wheeled Ergometer 16 2. K i n e t i c Energy, Boat, Ergometers, S u b j e c t 1 21 3. K i n e t i c Energy, S u b j e c t 1 And Boat 28 4. K i n e t i c Energy, S u b j e c t 2 42 5. K i n e t i c Energy, S u b j e c t 3 43 6. K i n e t i c Energy, S u b j e c t 4 44 v i Acknowledgement I w i s h t o thank Dr. D. Gordon E. Ro b e r t s o n f o r the guidance and p a t i e n c e he has p r o v i d e d me i n the p r e p a r a t i o n of t h i s t h e s i s . The p a t i e n c e and encouragement of the members of my t h e s i s committee, Dr. K. D. C o u t t s , Dr. D. C. McKenzie, and Mr. B. K l a v o r a were i m p o r t a n t i n my c a r r y i n g t h r o u g h w i t h t h i s paper t o the c o m p l e t i o n . The encouragement of my c l a s s m a t e s and of my f r i e n d s on the U n i v e r s i t y rowing crew a r e a l s o g r a t e f u l l y acknowledged. 1 INTRODUCTION T e s t i n g oarsmen's p h y s i o l o g i c a l c a p a b i l i t i e s w i t h o f f - w a t e r rowing s i m u l a t o r s i s not new. Henderson and Haggard (1925) r e p o r t use of an h y d r a u l i c rowing s i m u l a t o r t o t e s t the 1924 Y a l e U n i v e r s i t y r owing crew. Hagerman and c o - w o r k e r s , i n s e v e r a l s t u d i e s (1971, 1972, 1975a, 1975b, 1978, 1979) have r e p o r t e d p h y s i o l o g i c a l t e s t i n g of s e v e r a l hundred oarsmen s i n c e the e a r l y 1970's u s i n g the Lyons (Gamut E n g i n e e r i n g , Redwood C i t y , C a l i f o r n i a ) r o wing ergometer. The Canadian Amateur Rowing A s s o c i a t i o n uses G j e s s i n g rowing ergometers ( h e r e a f t e r r e f e r r e d t o as RE) (E. G j e s s i n g , P l a s t . r e k o n s t r . avd., H o s p i t a l e t B e t a n i e n , Bergen, Norway) t o t e s t Canadian oarsmen i n t h e i r t r a i n i n g f o r n a t i o n a l rowing teams. The Lyons ergometer s i m u l a t e s "sweep" r o w i n g , i n which the oarsman h a n d l e s one oar on one s i d e of the b o a t . An oarsman accustomed t o rowing on one s i d e of the boat i s a t a d i s a d v a n t a g e when he i s t e s t e d on a L y o n s - t y p e RE b u i l t f o r p e o p l e accustomed t o the o t h e r s i d e of the b o a t ; s c u l l e r s , accustomed t o rowing w i t h two o a r s i n a s y m m e t r i c a l motion a r e a t a d i s a d v a n t a g e as w e l l . The G j e s s i n g RE i s a " c e n t e r - p u l l " machine. A l l sweep oarsmen a r e a t a s i m i l a r ( s l i g h t ) d i s a d v a n t a g e on t h i s machine, as the h a n d l e does not p i v o t about a p o i n t a t e i t h e r s i d e of t h e boat. I n s t e a d , the h a n d l e i s g u i d e d s t r a i g h t backwards and f o r w a r d s by a bar a t t a c h e d t o the " o a r " h a n d l e . S c u l l e r s a r e a t the l e a s t d i s a d v a n t a g e on the G j e s s i n g machine, as they need o n l y a l t e r t h e i r arm m o t i o n , w h i l e sweep-oar rowers must adapt by removing the normal t w i s t and l e a n of t h e i r b o d i e s from t h e i r 2 rowing s t r o k e . The c h i e f d i s a d v a n t a g e t o the G j e s s i n g RE i s t h a t i t i s d i f f i c u l t t o row a t normal r a c i n g s t r o k e r a t e s f o r more th a n a few m i n u t e s , w h i l e i t i s n e c e s s a r y t o row a r a c i n g s h e l l f o r 6 t o 7.5 m i n u tes t o complete most r a c e s ( s t r i k i n g between 32 and 40 s t r o k e s per m i nute, u s u a l l y , depending on the r a c e ) . An RE c a p a b l e of s i m u l a t i n g the rowing motion and of s i m u l a t i n g the work o u t p u t r e q u i r e m e n t s of r a c e rowing i s a v a l u a b l e t o o l f o r use i n team s e l e c t i o n , t r a i n i n g , and i n t e c h n i c a l c o a c h i n g . The p r e s e n t G j e s s i n g machine a f f o r d s an a p p r o x i m a t i o n of the r owing m o t i o n . C u r r e n t p r a c t i s e i n the Canadian rowing community i s t o t e s t oarsmen f o r 6 minutes on a G j e s s i n g RE w i t h a r e s i s t a n c e of "3 kp" ( a p p r o x i m a t e l y 29.4 N) a p p l i e d t o each f l y w h e e l r e v o l u t i o n . The oarsman does "3 kp.m" or 29.4 J of work f o r each f l y w h e e l r e v o l u t i o n . These "rows" a r e u s u a l l y done w i t h s t r o k e r a t e s between 26 and 29 s t r o k e s per m inute; use of h i g h e r r a t e s o f t e n r e s u l t i n the oarsman p e r f o r m i n g p o o r l y because of e x c e s s i v e f a t i g u e i n the second h a l f of the t e s t . Lower s t r o k e r a t e s than 24-26 (depending upon the s i z e of the rower, the l a r g e r , s t r o n g e r rowers do v e r y w e l l a t the low end of t h i s continuum) r e s u l t i n p o o r e r s c o r e s because the f l y w h e e l ' s r e v o l u t i o n r a t e drops to o much between s t r o k e s , and e x c e s s i v e e f f o r t i s spent t o r e t u r n t h e f l y w h e e l t o a " c o m f o r t a b l e " speed. I t would be v a l u a b l e t o the rowing community i f the r e a s o n ( s ) f o r the d i f f i c u l t y i n rowing a t the s t r o k e r a t e s e x p e r i e n c e d i n normal r a c i n g c o u l d be d e f i n e d , so t h a t t h e G j e s s i n g RE c o u l d be r e d e s i g n e d t o s i m u l a t e the f e e l of r o wing more a c c u r a t e l y than i t does now. P r i o r t o any d e s i g n 3 changes, however, i t is necessary to study the rowing machine in comparison with real rowing to assess existing differences between rowing the Gjessing machine and the boat. Purpose The purpose of th i s study was to quantify and contrast the instantaneous segmental and t o t a l body mechanical energy patterns of rowing in a s i n g l e - s c u l l s racing s h e l l with rowing a Gjessing RE, and to contrast energy savings through exchanges of mechanical energy among segments and conversions of energy within segments. 4 METHODS S u b j e c t s S u b j e c t s i n c l u d e d 2 male s c u l l e r s and 2 female s c u l l e r s . One of each of t h e male and female s c u l l e r s were e x p e r i e n c e d i n i n t e r n a t i o n a l c o m p e t i t i o n . The o t h e r two s u b j e c t s were s i g n i f i c a n t l y l e s s e x p e r i e n c e d i n r a c e s c u l l i n g . B e f o r e any t e s t i n g or measuring each s u b j e c t was i n f o r m e d of the n a t u r e of the study and c o n s e n t e d t o p a r t i c i p a t e . B a s i c i n f o r m a t i o n about the s u b j e c t s i s i n T a b l e 1. T a b l e 1. Age, h e i g h t , and body mass of s u b j e c t s and masses of r a c i n g s h e l l s used i n rowing t r i a l s . S u b j e c t Sex Age H e i g h t Mass Boat Mass (cm) (kg) (kg) 1 m 23 187.5 85.4 17.6 2 m 20 197.0 90.5 22.5 3 f 22 1 68.5 64.5 20. 1 4 f 23 173.5 65.7 20.1 P r o c e d u r e s S u b j e c t s were f i l m e d rowing i n s i n g l e s c u l l s r a c i n g s h e l l s f o r s e v e r a l r owing s t r o k e c y c l e s a t s t r o k e r a t e s a t , above, and below t h e i r normal r a c i n g r a t e s . Rowing t r i a l s took p l a c e a t the Burnaby Lake Canada Games (1973) rowing c o u r s e . On a s e p a r a t e o c c a s i o n , s u b j e c t s were f i l m e d r owing a G j e s s i n g rowing ergometer (RE) a t s i m i l a r s t r o k e r a t e s t o those used i n the 5 rowing t r i a l s . A l l f i l m i n g was done u s i n g a m o t o r - d r i v e n Locam 16 mm camera (Redlake I n d u s t r i e s ) . A l l f i l m i n g was a t 25 frames per second ( f / s ) . M a r k e r s . Markers were p l a c e d a t the a n k l e ( l a t e r a l m a l l e o l u s ) , knee ( l a t e r a l f e m o r a l e p i c o n d y l e , about 2 cm s u p e r i o r t o the j o i n t l i n e ) , h i p ( g r e a t e r t r o c h a n t e r of femur), s h o u l d e r (acromion p r o c e s s ) , elbow ( l a t e r a l e p i c o n d y l e of the humerus), w r i s t ( s p i n o u s p r o c e s s of the u l n a ) , and neck ( p o s t e r i o r l y , on the s p i n o u s p r o c e s s of the f i r s t t h o r a c i c v e r t e b r a ( T 1 ) ) . The opening of the o u t e r ear was used as a marker f o r the head. A l l markers were p l a c e d on the s u b j e c t s ' r i g h t s i d e and a l l rowing was done w i t h the s u b j e c t s f a c i n g the r i g h t of the camera's image, f o l l o w i n g the c o n v e n t i o n of h a v i n g the s u b j e c t f a c e t h e p o s i t i v e x - a x i s of a normal C a r t e s i a n c o o r d i n a t e system. B e f o r e a l l water t r i a l s , markers were p l a c e d 3 m a p a r t on the p o r t s i d e (the s i d e n e a r e s t the camera) of the s u b j e c t ' s r a c i n g s h e l l . B e f o r e the ergometer t r i a l s , two markers were p l a c e d on the RE t o i d e n t i f y motion of the RE. S u b j e c t s ' body masses were measured w i t h a s c a l e a c c u r a t e t o w i t h i n 50 g or w i t h a K i s t l e r f o r c e p l a t e . Rowing S e s s i o n . S u b j e c t s were p r e p a r e d f o r t h e i r f i l m t r i a l s a f t e r rowing workouts ( w i t h i n 40 m i n ) . When ready, s u b j e c t s w a i t e d i n the a p p r o p r i a t e r a c i n g l a n e ( l a n e t h r e e of the Burnaby Lake c o u r s e , about 57 m from the camera), about 250 m t o the r i g h t of the camera. The s u b j e c t s t a r t e d t o row, 6 and was t o l d of his stroke rates so that he could adjust his tempo to equal that chosen for the t r i a l being rowed at the time. The subject's stroke rate was checked with a cal i b r a t e d "rate watch" just before his or her passing the camera. Ergometer Sessions. Subjects were permitted to row the RE u n t i l they f e l t comfortably "warmed up". When ready for filming, subjects started rowing the machine and used about six to eight strokes to atta i n their designated stroke rates, after which the rates were estimated with a stopwatch. The stroke rate was adjusted or maintained as required. When the subject was rowing at the correct tempo, f l o o d l i g h t s were turned on, and the camera was run for the time required to complete about 3 complete rowing cycles. During the filming, the stroke rate was checked as accurately as possible to make sure that the subject maintained the correct rate throughout the t r i a l . After each t r i a l the subject rested momentarily. The filming was repeated at the other stroke rates. The RE t r i a l s were repeated with the RE mounted on a wheeled ca r t . Manufacturer's s p e c i f i c a t i o n s for the Gjessing RE are such that the machine i s mounted on wheels aligned with the longitudinal axis of the ergometer. The CARA-owned machine has no wheels. Data C o l l e c t i o n and Analysis Films were projected onto a d i g i t i z i n g table one frame at a time. The cartesian coordinates of a l l markers in each frame were " d i g i t i z e d " with a Numonics Graphics Calculator interfaced 7 w i t h a microNova computer (Data G e n e r a l C o r p . ) . One f u l l s t r o k e c y c l e of each t r i a l was d i g i t i z e d ( c a t c h - t o - c a t c h ) . Programmes used l a t e r i n the d a t a p r o c e s s i n g r e q u i r e d t h a t 6 frames b e f o r e the b e g i n n i n g of the s t r o k e and 6 frames a f t e r the end of the s t r o k e were d i g i t i z e d . Data were then t r a n s m i t t e d t o an Amdahl 470/V8 computer f o r e r r o r c h e c k i n g , k i n e m a t i c , and energy quant i f i c a t i o n . P e r s p e c t i v e e r r o r i n the c o o r d i n a t e d a t a , caused by the camera p o s i t i o n b e i n g such t h a t t h e movement was not p e r p e n d i c u l a r t o the o p t i c a l a x i s of the camera, was removed w i t h a m a t r i x t r a n s f o r m a t i o n adapted from t h a t d e s c r i b e d i n W o l t r i n g (1975, 1976). Data were then smoothed by two passes (one f o r w a r d and one backward t o e l i m i n a t e p h a s e - s h i f t ) of a low-pass d i g i t a l f i l t e r u s i n g a 5 Hz c u t o f f f r e q u e n c y f o r the ergometer d a t a . Data f o r the boat t r i a l s were f i l t e r e d u s i n g 2.5 Hz as the c u t o f f f o r the d i g i t a l f i l t e r t o r e t a i n as much of the " s i g n a l " as p o s s i b l e w h i l e r e d u c i n g h i g h f r e q u e n c y n o i s e . The d i g i t a l f i l t e r i n g method of r e d u c i n g " n o i s e " i n f i l m c o o r d i n a t e d a t a has been v a l i d a t e d by Pe z z a c k , Norman, and W i n t e r (1977). A n t h r o p o m e t r i c d a t a f o r each s u b j e c t were t a k e n from t a b l e s p r o v i d e d by Dempster ( i n W i n t e r , 1979b), based on s u b j e c t w e i g h t . L i n k segment a n a l y s i s of the f i l m d a t a gave the i n s t a n t a n e o u s (frame-by-frame) l i n e a r and a n g u l a r d i s p l a c e m e n t s , v e l o c i t i e s and a c c e l e r a t i o n s of the segments; e n e r g i e s and r a t e s of change of m e c h a n i c a l e n e r g i e s of a l l segments and of the t o t a l body were c a l c u l a t e d . E n e r g i e s of a l l segments were c a l c u l a t e d assuming t h a t a l l segments r e t u r n e d t o the same 8 p o s i t i o n a t the c o m p l e t i o n of each s t r o k e . In t h i s s i t u a t i o n , t h e r e i s no net e x t e r n a l work done on the body or by the body, as t h e r e i s no change from s t r o k e t o s t r o k e i n the h e i g h t of the body or i n i t s v e l o c i t y . Segmental Energy. E n e r g i e s of the segments and of the t o t a l body were c a l c u l a t e d as d e s c r i b e d by W i n t e r , (1979a). The energy of each segment (E ) was c a l c u l a t e d w i t h the f o r m u l a : s E = P o t e n t i a l energy (E ) s p + T r a n s l a t i o n a l k i n e t i c energy (E ) kt + R o t a t i o n a l k i n e t i c energy (E ) kr = mgh + 1/2 mv 2 + 1/2 Ia>2 (1) where m = segment mass i n kg g = g r a v i t a t i o n a l a c c e l e r a t i o n (9.8 m/s 2) h = h e i g h t of segment mass c e n t r e i n m v = a b s o l u t e v e l o c i t y of the segment mass c e n t r e i n m/s I = r o t a t i o n a l moment of i n e r t i a of the segment i n kg.m 2 co = r o t a t i o n a l v e l o c i t y of the segment i n r a d / s . T o t a l Body Energy. The i n s t a n t a n e o u s energy of the t o t a l body (E ) was c a l c u l a t e d by summing the e n e r g i e s of a l l of the t segments i n each f i l m frame: B E = Z E (2) t s=1 s where B was the number of segments and, E was the t o t a l energy of segment s i n each f i l m frame, s 9 I n t e r n a l Work. C a l c u l a t i o n o f t h e t o t a l i n t e r n a l work i n t h e r o w i n g s t r o k e r e q u i r e d i n c l u s i o n o f i n t e r n a l a n d e x t e r n a l w o r k . A c o n c e n t r i c ( s h o r t e n i n g ) m u s c l e c o n t r a c t i o n i s s a i d t o do p o s i t i v e work on a seg m e n t , i n c r e a s i n g t h e t o t a l e n e r g y o f t h a t s e g m e n t ; an e c c e n t r i c ( l e n g t h e n i n g a g a i n s t t h e c o n t r a c t i o n c a u s e d by some e x t e r n a l moment) c o n t r a c t i o n i s s a i d t o do n e g a t i v e w o r k , d i s s i p a t i n g m e c h a n i c a l ( k i n e t i c ) e n e r g y a n d d e c r e a s i n g t h e t o t a l body e n e r g y ( W i n t e r , 1 9 7 9 a ) . S i n c e r o w i n g i s u s u a l l y done on a f l a t o r n e a r l y f l a t s u r f a c e ( i . e., w i t h no a p p r e c i a b l e c u r r e n t ) t h e r e s h o u l d be l i t t l e i f a n y c h a n g e i n t h e m e c h a n i c a l e n e r g y o f t h e s y s t e m f r o m one s t r o k e t o t h e n e x t . The s y s t e m d o e s c h a n g e i t s d r a f t a n d h o r i z o n t a l v e l o c i t y d u r i n g a s t r o k e , b u t a t s t e a d y p a c e r o w i n g t h e c h a n g e s a r e r e p e a t e d e v e r y s t r o k e . The b o a t a n d r o w e r r e t u r n t o t h e same h e i g h t a n d v e l o c i t y a n d t h u s t o t h e same m e c h a n i c a l e n e r g y a t c o r r e s p o n d i n g p o i n t s o f c o n s e c u t i v e s t r o k e s . I n p r e v i o u s s t u d i e s o f m e c h a n i c a l e n e r g y ( e . g., P i e r r y n o w s k i , e t a _ l . , 1980, 1 981 ) t o t a l e n e r g i e s have been f o u n d t o v a r y s l i g h t l y a t c o r r e s p o n d i n g s t a g e s o f c y c l i c movements ( w a l k i n g a n d l o a d e d w a l k i n g ) . The s l i g h t c h a n g e b e t w e e n f i n i s h i n g e n e r g y (E ) a n d s t a r t i n g e n e r g y t n (E ) a p p e a r s a s e x t e r n a l work (W ) due t o movement o f t h e t o t a l to t body o r c h a n g e s i n i t s movement: N W = Z AE t i=1 - t i =E - E (3) t n tO I n t h i s s t u d y i t was p r e s u m e d t h a t t h e r e was no c h a n g e i n t o t a l e n e r g y ( t h u s no W ) b e t w e e n c o r r e s p o n d i n g p o i n t s o f c o n s e c u t i v e t 10 s t r o k e s . T h i s c o n s t r a i n e d a l l segmental energy components t o r e t u r n t o t h e i r o r i g i n a l l e v e l s a t the end of each s t r o k e . W , t t h e n , a c c o u n t e d f o r e x t e r n a l work done i n the t r i a l , and was s u b t r a c t e d from the t o t a l energy of the s t r o k e p r i o r t o c a l c u l a t i o n of t h e exchanges among or i n t e r c o n v e r s i o n s w i t h i n segments. " T h i s c o r r e c t i o n assumes t h a t the t o t a l body b e g i n s and ends a t the same energy l e v e l and t h i s i s t r u e a c r o s s many..." s t r o k e s u n l e s s t h e s u b j e c t i s c h a n g i n g h i s or her average v e l o c i t y w i t h each s t r o k e ( q u o t a t i o n from P i e r r y n o w s k i , 1978). The t o t a l i n t e r n a l work (W ) ( d e f i n e d by W i n t e r , 1979a) of i t h e s c u l l i n g s t r o k e was c a l c u l a t e d by t a k i n g the sum of the a b s o l u t e changes of the t o t a l body energy (AE ) over the number t of frames of the s t r o k e (N). T h i s c a l c u l a t i o n d e t e r m i n e d i n t e r n a l work assuming t h a t energy can be both i n t e r c o n v e r t e d and exchanged where i n t e r c o n v e r s i o n of energy w i t h i n a segment i m p l i e s c o n v e r s i o n from p o t e n t i a l energy t o k i n e t i c energy or v i c e - v e r s a , and exchange of energy i m p l i e s the t r a n s m i s s i o n of m e c h a n i c a l energy from segment t o segment. N W = -W + Z |AE | (4) i t i=1 t i The t o t a l work r e q u i r e d assuming t h a t t h e r e was energy exchange among segments but no i n t e r c o n v e r s i o n of energy w i t h i n segments (W ) was g i v e n by: e 11 N B W = -W + L I |AE | (5) e t i = 1 s=1 s i T o t a l work i f t h e r e was n e i t h e r exchange nor i n t e r c o n v e r s i o n (W ) was c a l c u l a t e d by summing the a b s o l u t e v a l u e s of the n changes i n the segmental energy components over t h e number of segments (B) and over the number of frames (N) i n the movement: W = -w + n t N B L L ( | AE | + | AE | + | AE | ) (6) i=1 s=1 p s i k t s i k r s i I t i s p o s s i b l e t o use the t h r e e v a l u e s W , W , and W t o n i e c a l c u l a t e the amount of energy "saved" or " p r e s e r v e d " i n the motion by i n t e r c o n v e r s i o n o f , or exchange of m e c h a n i c a l energy. The appearance of t h e s e exchanges or c o n v e r s i o n s of m e c h a n i c a l energy reduce the need f o r the muscles t o a b s o r b energy i n one p l a c e w h i l e g e n e r a t i n g energy i n a n o t h e r . Energy saved ( c . f . , " c o n s e r v e d " W i n t e r , 1979b) due t o i n t e r c o n v e r s i o n s w i t h i n segments (S ) was c a l c u l a t e d as the d i f f e r e n c e between the work i a l l o w i n g n e i t h e r exchange nor c o n v e r s i o n (W ) and the work n a l l o w i n g exchange but no c o n v e r s i o n (W ). The amount of energy e saved t h r o u g h i n t e r c o n v e r s i o n s w i t h i n segments i s e x p r e s s e d as a p e r c e n t a g e of the t o t a l work t h a t would have been r e q u i r e d i f no energy had been c o n v e r t e d or exchanged (W ) ( i . e., i f muscles n were needed t o g e n e r a t e or a b s o r b a l l energy changes, and no c o n v e r s i o n of energy o c c u r r e d ) . S = 100 (W - W ) / W . (7) i n e n 12 Energy saved due t o exchanges among segments (S ) was e c a l c u l a t e d as the d i f f e r e n c e between W and the i n t e r n a l work n a l l o w i n g exchange and t r a n s f e r (W ). T h i s f i g u r e was e x p r e s s e d i as a p e r c e n t a g e of W : n S = 100 (W - w ) / W . (8) e e i n The change i n energy of the t o t a l system (body and boat) from i t s l o w e s t v a l u e j u s t b e f o r e the c a t c h t o i t s h i g h e s t v a l u e j u s t b e f o r e the f i n i s h may be used t o d e r i v e the average power of the d r i v e phase of the s t r o k e . The d a t a f o r the t o t a l energy of the system was scanned, and t h e s c o r e s f o r the l o w e s t and h i g h e s t m e c h a n i c a l e n e r g i e s were r e c o r d e d , w i t h t h e i r r e s p e c t i v e t i m e s . The average d r i v e power (P ) was c a l c u l a t e d a s : d ( h i g h e s t M. E. - l o w e s t M. E.)/Atime (9) where -Atime was the e l a p s e d time of the energy change The average v e l o c i t y (v) d u r i n g the s t r o k e was c a l c u l a t e d a s : ( d i s p l a c e m e n t , c a t c h t o c a t c h ) / A t i m e (10) where -Atime was the time r e q u i r e d t o complete the s t r o k e from c a t c h t o c a t c h . 13 RESULTS AND DISCUSSION Cinematography Boat T r i a l s . A f i e l d of view of a p p r o x i m a t e l y 20 m i n the movement p l a n e was r e q u i r e d t o p e r m i t f i l m i n g of a t l e a s t one complete s t r o k e c y c l e ( c a t c h - t o - c a t c h or f i n i s h - t o - f i n i s h ) and ten frames b e f o r e and a f t e r t he c y c l e ' s end p o i n t s . The p r o j e c t e d images c o u l d not be e n l a r g e d t o more than about 3 % of l i f e s i z e due t o the l i m i t e d span of the d i g i t i z e r , about 55 cm). W e l l s and C a l d w e l l (1982) r e p o r t the r o o t mean square of the d i f f e r e n c e s between f i l t e r e d and u n f i l t e r e d f i l m d a t a (RMSD) as an i n d i c a t i o n of d i g i t i z a t i o n n o i s e . The RMSD i n c r e a s e d as the r a t i o of t r u e s i z e t o image s i z e i n c r e a s e d . The l a r g e s t such r a t i o e x p e r i e n c e d by W e l l s and C a l d w e l l (1982) was about 16:1, w h i l e the same r a t i o f o r the d a t a f o r the rowing t r i a l s i n t h i s s t u d y was about 34:1. RMSD was g r e a t e s t i n the x-c o o r d i n a t e of the a n k l e (23±4 mm, meant 1 s t a n d a r d d e v i a t i o n ) and l e a s t i n the y - c o o r d i n a t e d a t a f o r the boat (11±2) mm). The RMSD i n most of the rowing d a t a were s i m i l a r t o or s l i g h t l y g r e a t e r than t h a t of W e l l s and C a l d w e l l , u s i n g images a p p r o x i m a t e l y one h a l f of the s i z e found i n the p r e v i o u s s t u d y . T h i s s i m i l a r i t y , u s i n g images as s m a l l as 3 % l i f e - s i z e s u g g e s t s t h a t the a c c u r a c y of the d i g i t i z a t i o n was of s u f f i c i e n t a c c u r a c y t o p e r m i t d i s c u s s i o n of m e c h a n i c a l energy w i t h r e s p e c t t o the rowing t r i a l s . Ergometer T r i a l s . The t r u e s i z e t o image s i z e r a t i o s i n th e RE t r i a l s were about 9:1 f o r a l l t r i a l s ; t h e RMSD of t h e f i l m d a t a i n t h i s case was l e s s than 5 mm f o r a l l of the marker 14 c o o r d i n a t e s . The x - c o o r d i n a t e of the a n k l e marker a g a i n showed the g r e a t e s t v a r i a b i l i t y (average RMSD = 4.2±1.2 mm). T h i s s m a l l RMSD i n the RE f i l m d a t a s u g g e s t s t h a t the d i g i t i z a t i o n of the RE t r i a l s was a c c u r a t e . T r i a l s were a s s i g n e d codes t o i d e n t i f y t h e d a t a f o r the a n a l y s i s . "RB1A1," f o r example, r e f e r s t o Rowing, Boat, s u b j e c t j _ , s t r o k e r a t e "A" (a low s t r o k e r a t e - "B" i m p l i e s a medium r a t e , and "C" a h i g h r a t e ) , t r i a l j _ . A "W" was used t o denote wheeled RE t r i a l s , and "S" was used t o denote t r i a l s u s i n g the s t a t i o n a r y t r i a l s . S t i c k f i g u r e s of the movements of a s u b j e c t rowing on t h e s t a t i o n a r y RE and on the wheeled RE a r e p r e s e n t e d i n F i g u r e s 1A and 1B, r e s p e c t i v e l y . Note t h a t the s u b j e c t ' s body t r a n s l a t e s on the ergometer w h i l e the RE does not move ( c . f . the " a n k l e " p o s i t i o n i n F i g . 1A). On the wheeled RE, however, the s u b j e c t ' s body t r a n s l a t e s v e r y l i t t l e , and the RE i s moved ( c . f . the n e a r l y s t a t i o n a r y " h i p " and the moving " a n k l e " p o s i t i o n s i n F i g . 1B). I n t e r n a l Work A l l i n t e r n a l work measures (W , W ,W ) were g r e a t e s t i n i e n the rowing t r i a l s and l e a s t i n the wheeled RE t r i a l s ( T a b l e s 2 t o 4 ) . The major d i f f e r e n c e s between work s c o r e s i n rowing t r i a l s and i n ergometer t r i a l s were due t o the d i f f e r e n c e s i n the t r a n s l a t i o n a l energy of the t e s t d e v i c e s . These t r a n s l a t i o n a l e n e r g i e s were g r e a t e s t i n the rowing t r i a l s because t h e system of rower and boat moved s e v e r a l metres d u r i n g each s t r o k e ; t h e s e movements o c c u r r e d a t c h a n g i n g v e l o c i t i e s DRIVE PHASE OF ROWING A STATIONARY ERGOMETER FIGURE 1 A. DRIVE PHASE OF ROWING A WHEELED ERGOMETER FIGURE 1 B 17 T a b l e 2. I n t e r n a l work ( j o u l e s ) and energy s a v i n g s ( p e r c e n t ) f o r the s c u l l i n g t r i a l s . S u b j e c t W S S T r i a l i e i Code 832.2 27.6 18.7 RB1A1 1 1153. 1 27.6 13.5 RB1B2 970.7 38.1 14.8 RB1C3 1657.6 22.8 15.0 RB2A1 2 1267.6 36.4 9.9 RB2B2 1655.2 19.5 12.2 RB2C3 594.0 32. 1 16.8 RB3A1 3 909.6 32.3 11.6 RB3B2 788.2 33. 1 15.0 RB3C3 696.2 27.0 15.7 RB4A1 4 756. 1 31.0 13.8 RB4B2 794.4 40.4 12.3 RB4C4 MEAN SD 30.6 6.1 14.2 2.4 18 Table 3. Internal work (joules) and energy savings (percent) for the wheeled RE t r i a l s . iject W S S T r i a l i e i Code 245.6 31 .2 17.7 RW1A1 1 280.9 29.0 16.9 RW1B2 336.5 24.7 15.3 RW1C3 310.7 28.8 19.5 RW2A1 2 314.0 25.2 21.7 RW2B2 335.3 25.5 18.0 RW2C3 213.3 22.3 17.3 RW3A4 3 211.7 30.0 1 1 .8 RW3B5 212.0 32.6 16.1 RW3C6 181.0 23.3 22.6 RW4A1 4 1 93.4 21 .4 22.4 RW4B2 236.0 17.6 21 .8 RW4C3 MEAN SD 26.0 4.5 18.9 3.3 19 T a b l e 4. I n t e r n a l work ( j o u l e s ) and e n e r g y s a v i n g s ( p e r c e n t ) f o r t h e s t a t i o n a r y RE t r i a l s . lub j e c t W S S T r i a l i e i Code 361 .4 24.1 13.0 RS 1A4 1 3 6 7 . 9 2 3 . 0 11.8 RS1B5 551 .9 1 1.9 8 .2 RS1C7 4 6 8 . 8 2 2 . 2 1 1 .2 RS2A4 2 3 5 3 . 6 30.1 18.2 RS2B5 4 5 8 . 6 2 4 . 3 11.4 RS2C6 2 3 3 . 0 2 5 . 4 13.2 RS3A1 3 2 6 5 . 4 2 2 . 6 10.6 RS3B2 2 5 6 . 8 2 8 . 7 12.6 RS3C3 199.7 2 9 . 2 16.2 RS4A4 4 2 8 2 . 4 2 0 . 7 14.1 RS4B5 3 2 0 . 3 16.0 15.5 RS4C6 MEAN 2 3 . 2 13.0 SD 5.3 2.7 20 w i t h i n the s t r o k e s . I n the RE t r i a l s t h e r e was v e r y l i t t l e movement of the body o t h e r than t h a t on the s l i d e . W i t h no movement of the RE r e l a t i v e t o the e x t e r n a l environment (as e x i s t s i n t h e b o a t ) , t h e r e was no measure of the change of energy of the system of s u b j e c t - R E t h a t was p r o b a b l y r e f l e c t e d i n t he changes i n the a n g u l a r v e l o c i t y of the f l y w h e e l of t h e RE. M o t i o n of the RE i n the wheeled t r i a l s was not g r e a t enough t o cause s i g n i f i c a n t changes of energy i n the system of s u b j e c t and RE. The d i f f e r e n t i n t e r n a l work v a r i a b l e s enumerate changes i n the components of t h e e n e r g i e s of the segments. The c u r v e s shown i n F i g u r e 2 show the k i n e t i c e n e r g i e s of s e l e c t e d energy v a r i a b l e s a t t h e same s t r o k e r a t e on t h e d i f f e r e n t d e v i c e s . The to p c u r v e d e m o n strates the g r e a t e r changes i n the t o t a l m e c h a n i c a l energy of the s u b j e c t i n t h e rowing t r i a l s . The W i t e rm i s made up of t h e frame-by frame changes i n t h e t o t a l body energy, of which the t o p cu r v e i n F i g u r e 2 l a c k s o n l y the p o t e n t i a l energy (which i s e s s e n t i a l l y a b i a s , i n rowing) of t h e e n t i r e system and the energy of the bo a t . In the rowing t r i a l s , the changes i n the energy of the system ( t h e work) r e f l e c t t h e s u b j e c t s ' e f f o r t s t o move the boat t h r o u g h the m a n i p u l a t i o n s of the o a r s . The magnitude of the changes i n energy t h r o u g h t h e d r i v e , c o u p l e d w i t h the d u r a t i o n of the d r i v e ( i . e., power) r e f l e c t t he e f f e c t i v e n e s s of the rowing m o t i o n s . These powers a r e d i s c u s s e d l a t e r i n t h i s paper. The i n t e r n a l work v a l u e s seen i n t a b l e s 2 t o 4 may be compared w i t h i n t e r n a l work s c o r e s between 48.5 and 251.7 f o r l e v e l w a l k i n g (Winter 1979a). P i e r r y n o w s k i , e t a l . , (1980), 21 TOTAL BODY AND TQRSQ^THIGHS KINETIC ENERGY SUBJECT 1. TRIAL CODE: SUBJ 1 A — A BODY UN BOAT) TIME (SECONDS) FIGURE 2 . 22 found work v a l u e s i n t r e a d m i l l w a l k i n g which averaged 165.7 (W ), 340.2 (W ), and 500.9 (W ); v a l u e s f o r i n t e r n a l work i e n c a r r y i n g a v a r i e t y of e x t e r n a l l o a d s d u r i n g t r e a d m i l l w a l k i n g ranged from 328 t o 423 (W ) ( P i e r r y n o w s k i , e t a l . , 1981). These e r e s e a r c h e r s were a b l e t o i n c l u d e the speed of the t r e a d m i l l b e l t i n t h e i r i n v e s t i g a t i o n s , t o g i v e an e s t i m a t e of the " v e l o c i t y " of t h e i r s u b j e c t s m o t i o n s . Such a measure was not p o s s i b l e d u r i n g the p r e s e n t s t u d y , as the equipment a v a i l a b l e , and time and f i n a n c i a l c o n s t r a i n t s p r e v e n t e d development of and adequate measure of the a n g u l a r v e l o c i t y of the f l y w h e e l d u r i n g the RE t r i a l s . S c o r e s f o r W i n the boat t r i a l s i n the p r e s e n t s t u d y i were c o n s i d e r a b l y h i g h e r than s c o r e s f o r the w a l k i n g t r i a l s i n t h e s e o t h e r s t u d i e s . The work d a t a f o r the s t a t i o n a r y RE are s l i g h t l y h i g h e r than f o r the wheeled RE. The reason f o r t h i s i s a p p arent i n comparing F i g u r e s 1A and 1B and i n the bottom s e t s of c u r v e s i n F i g u r e 2. The l a c k of motion i n the s t a t i o n a r y RE causes the s u b j e c t t o have t o a c c e l e r a t e and d e c e l e r a t e most of h i s body a t each end of the s t r o k e i n a d d i t i o n t o moving the RE's oar h a n d le t h r o u g h the s t r o k e . T h i s i s not l i k e rowing a b o a t , i n which the boat moves w i t h the rower, and a l l o w s the s u b j e c t t o move the boat (which weighs about 20-25% of the s u b j e c t ) r e l a t i v e t o h i m s e l f , i n s t e a d of a l l of the s u b j e c t ' s motions b e i n g a b s o l u t e w i t h r e s p e c t t o the environment. i . e . , The s u b j e c t ' s movements i n a s h e l l cause the boat t o change i t s v e l o c i t y r e l a t i v e t o b o t h the s u b j e c t and t h e e x t e r n a l r e f e r e n c e system, w h i l e the i m m o b i l i t y of the s t a t i o n a r y RE f o r c e s a l l of the s u b j e c t ' s 23 motions t o be r e l a t i v e o n l y t o the e x t e r n a l system of r e f e r e n c e s i n c e the frame of the RE does not move p e r c e p t i b l y i n response t o the s u b j e c t ' s a c t i o n s . The g e n e r a l shape of the bottom s e t s of c u r v e s i n F i g u r e 4 i s due t o the need f o r the s u b j e c t t o come t o a complete s t o p a t each end of the s l i d e . A f t e r s t o p p i n g the movement of the d r i v e , the s u b j e c t was then r e q u i r e d t o a c c e l e r a t e h i s e n t i r e body i n the o p p o s i t e d i r e c t i o n f o r the r e c o v e r y . The h i g h peak of the s u b j e c t ' s energy d u r i n g the d r i v e was due t o the v e l o c i t y w i t h which the s u b j e c t moved d u r i n g the d r i v e . The lower peak i n the energy of the system i n the r e c o v e r y was due t o the s u b j e c t p e r f o r m i n g e s s e n t i a l l y the r e v e r s e of the d r i v e phase, but more s l o w l y . W i t h no measure of the f l y w h e e l ' s i n s t a n t a n e o u s r o t a t i o n a l v e l o c i t y t h e r e i s no c l e a r way t o compare the i n t e r n a l work i n the ergometer c o n d i t i o n s w i t h the i n t e r n a l work i n t h e rowing t r i a l s . The e f f e c t of the rower's movements on the boat a r e e v i d e n t i n the i n s t a n t a n e o u s changes i n the v e l o c i t y of the system. The a n g u l a r v e l o c i t y of the f l y w h e e l would r e f l e c t t h e s e e f f o r t s i n the ergometer, and c o u l d be used t o g i v e energy v a l u e s which c o u l d be used t o compare the i n t e r n a l work s c o r e s of the d i f f e r e n t t e s t d e v i c e s . F u t u r e r e s e a r c h i n t h i s a r e a must i n c l u d e such a measure. Energy Exchanges and I n t e r c o n v e r s i o n s C a l c u l a t i n g s a v i n g s of energy by exchange and i n t e r c o n v e r s i o n a v o i d s the problem of comparing i n t e r n a l work s c o r e s by p e r m i t t i n g the comparison of the p r o p o r t i o n a l d i f f e r e n c e s between the "work" v a l u e s . Energy s a v i n g s c a l c u l a t e d from E q u a t i o n s 7 and 8 a r e p r e s e n t e d i n the second 24 and t h i r d d a t a columns of T a b l e s 2, 3, and 4. The S and S e i v a l u e s a r e e x p r e s s e d as p e r c e n t a g e s of the t o t a l m e c h a n i c a l work i f n e i t h e r exchange nor c o n v e r s i o n of energy a r e p e r m i t t e d . The energy exchange term (S ) may be used t o d i s c u s s some e of t h e d i f f e r e n c e s between rowing and rowing e r g o m e t e r s . A l a r g e r p r o p o r t i o n of the t o t a l apparent "work" (W ) appears t o n be t r a n s m i t t e d from the body t o the d e v i c e i n s c u l l i n g t han i n e i t h e r RE c o n d i t i o n , w i t h v i s i b l e e f f e c t on t h e s h e l l . T h i s i s a p p a r e n t from the l a r g e r S s c o r e s i n the s c u l l i n g d a t a e ( T a b l e 5 ) . That the S i n the wheeled RE was g r e a t e r than the e S i n t h e s t a t i o n a r y RE but l e s s than t h a t i n the boat, and t h a t e the o n l y r e a l d i f f e r e n c e between the two RE c o n d i t i o n s was the motion of the RE ( r e f e r t o F i g u r e 1 A and B) d u r i n g the s t r o k e r e i n f o r c e s t h i s s u g g e s t i o n . As w e l l , s u b j e c t s c l a i m e d t h a t the wheeled RE " f e l t " s l i g h t l y more l i k e r e a l r o wing than d i d rowing the s t a t i o n a r y RE. I n t e r c o n v e r s i o n of energy w i t h i n segments (S ) was g r e a t e s t i i n t h e wheeled RE and was v e r y s i m i l a r f o r the s c u l l i n g and the s t a t i o n a r y RE d a t a . The main sou r c e of t h e d i f f e r e n c e i n e s t i m a t e d S may have been the presence or absence of l a r g e i amounts of t r a n s l a t i o n a l energy changes i n t h e segments. In the wheeled RE most of the motion of the t h i g h s and lower l e g s segments, f o r example, was e i t h e r r o t a t i o n a l or t r a n s l a t i o n a l i n the v e r t i c a l d i r e c t i o n o n l y . W i t h the s t a t i o n a r y RE and w i t h 25 T a b l e 5. Power i n d r i v e , average v e l o c i t y , s t r o k e r a t e and average power. T r i a l D r i v e Average S t r o k e Average E s t . Code Power V e l . Rate Power 2000 i (W) (m/s) (/min) (W) Time RB1A1 377 3.75 25.6 161 8'53" * RB1B2 859 4.57 32 459 7' 18" * RB1C3 962 4.74 32 514 7' 02" RB2A1 462 3.66 20.4 157 9'07" RB2B2 434 3.87 24. 1 174 8' 37" * RB2C3 757 4.42 32 404 7' 32" RB3A1 309 3.51 24.7 127 9*29" RB3B2 468 4.07 29.5 230 8' 1 1 " RB3C3 655 4.21 32 350 7'55" RB4A1 521 3.72 26 226 8*57" RB4B2 566 4.21 30.7 290 7'55" RB4C4 560 4.59 36.6 343 7' 15" 26 the rowing s h e l l , t h e r e was a l a r g e h o r i z o n t a l t r a n s l a t i o n a l component t o the motion i n a d d i t i o n t o the r o t a t i o n a l and v e r t i c a l movement components. Thus the c h i e f d i f f e r e n c e between the s t a t i o n a r y and the wheeled c o n d i t i o n s i s due t o the c o m p u t a t i o n of the S w h i c h , as a p e r c e n t a g e of the t o t a l i a p p a r e nt change i n energy, i s i n c r e a s e d i n the wheeled RE because of the absence of the r e l a t i v e l y l a r g e h o r i z o n t a l components seen i n t h e motions of the s u b j e c t i n the s t a t i o n a r y RE and boat t r i a l s . There was no apparent r e l a t i o n s h i p between the p e r c e n t a g e of energy saved i n the t h r e e d e v i c e s and the s t r o k e r a t e . A l t h o u g h t h e r e was an i n s u f f i c i e n t number of s u b j e c t s t o warrant i n f e r e n t i a l s t a t i s t i c s , the d i f f e r e n c e s between the means shown i n T a b l e s 2 t o 4 a r e worth n o t e . The mean S f o r the boat was e s i g n i f i c a n t l y d i f f e r e n t from the v a l u e s f o r both ergometer c o n d i t i o n s (t=2.14, p ^ 0 . 0 5 , boat v e r s u s wheeled RE, and t = 3 . l 9 , p ^ 0.01 ,boat v e r s u s s t a t i o n a r y e r g o m e t e r ) . These d i f f e r e n c e s suggest t h a t f u r t h e r i n v e s t i g a t i o n of exchange of energy i n rowing may be w o r t h w h i l e . (No attempt may be made t o use the d a t a from t h i s s t u d y t o p r e d i c t the m e c h a n i c a l energy s a v i n g s of o t h e r s c u l l e r s because of the s m a l l sample s i z e i n the s t u d y and because of the v a s t d i f f e r e n c e s between the a b i l i t i e s of the e x p e r i e n c e d and i n e x p e r i e n c e d s u b j e c t s . ) I d e n t i f i c a t i o n of the s o u r c e s of energy exchange among segments ( i n c l u d i n g the r a c i n g s h e l l ) may be a method f o r a t t e m p t i n g t o m a n i p u l a t e rowing t e c h n i q u e s t o maximize b o t h exchange of m e c h a n i c a l energy and the average v e l o c i t y of the r a c i n g s h e l l . 27 The p o s s i b i l i t y of the presence of exchanges of energy between the s u b j e c t and the s h e l l i s r e i n f o r c e d by the p a t t e r n s of t h e c u r v e s f o r the s u b j e c t and boat i n F i g u r e 3. Between t h e low e s t p o i n t of the s u b j e c t ' s E c u r v e ( a t about 1.75 s) and kt t he c a t c h ( i n d i c a t e d by "CAT") a t about 2.00 s, the energy of the boat f e l l , w h i l e t h a t of the s u b j e c t i n c r e a s e d . The k i n e t i c energy of the s h e l l was e x p e c t e d t o f a l l , as i t was under the i n f l u e n c e of drag from the water. The energy of the s u b j e c t was not e x p e c t e d t o i n c r e a s e b e f o r e t h e c a t c h , s i n c e t h e s u b j e c t was s t i l l a p p r o a c h i n g the f r o n t of the s l i d e w i t h h i s o a r s out of the water. D u r i n g the r e c o v e r y phase of a s t r o k e rowers t r y t o mi n i m i z e d i s t u r b a n c e s of the motion of a boat by r e d u c i n g e x c e s s motion t o a minimum. The o n l y s o u r c e from which the s u b j e c t c o u l d have r e c e i v e d energy a t t h a t p o i n t was the b o a t . The p a t t e r n of the E c u r v e s between about 0.75 s and about 1.75 s kt ( d u r i n g the r a p i d d e c r e a s e i n the energy of the s u b j e c t ) p e r m i t s s p e c u l a t i o n t h a t f u r t h e r energy s a v i n g e x i s t s as exchange from s u b j e c t t o b o a t . In t h a t e n t i r e second, d u r i n g which the E of k t the s u b j e c t f e l l from i t s peak t o i t s l o w e s t p o i n t i n the c y c l e , the E of the boat i n c r e a s e d almost c o n t i n u o u s l y . The energy kt c a u s i n g the b o a t ' s energy t o i n c r e a s e must have come from the s u b j e c t t h r o u g h h i s c o n n e c t i o n t o the boat a t the f e e t , s i n c e the o n l y o t h e r s o u r c e of energy change i n the system was the v i s c o u s d r a g of the w a t e r . C l e a r l y , t h e d r a g of t h e water d i d not add t o the energy of the b o a t . These exchanges of energy among boat and crew have been e v i d e n t f o r y e a r s , and a r e 28 TOTAL BODY AND BOAT KINETIC ENERGY SUBJECT 1 TRIAL CODE'. RB1C3. A — A SUBJECT K. E. TIME 1SECOND-SJ FIGURE 3 . 29 a p p arent i n the changes of h u l l v e l o c i t y d u r i n g the s t r o k e ( e . g., M a r t i n and B e r n f i e l d , 1980). A l i t e r a t u r e s e a r c h found no p r e v i o u s a t t e m p t s t o q u a n t i f y the exchanges of energy between boat and rower. That the S and p a r t i c u l a r l y t h e S v a l u e s a r e h i g h e r i n i e t h e wheeled RE c o n d i t i o n a l l o w the s p e c u l a t i o n t h a t an oarsman would be c a p a b l e of p r o d u c i n g g r e a t e r work o u t p u t i n a 6 min RE t e s t on an ergometer mounted on wheels or r o l l e r s . The f e a s i b i l i t y of such a t e s t might be i n c r e a s e d by t e t h e r i n g the RE a t each end of the machine w i t h a "damped e l a s t i c , " as t h e r e i s a tendency f o r the machine t o t r a v e l " s t e r n w a r d " d u r i n g r o wing when mounted on wheels. Average D r i v e Power The powers of the d r i v e phase (P of the s c u l l i n g s t r o k e s , d t h e average . v e l o c i t y of t h e s h e l l t h r o u g h o u t the s t r o k e s ( c a t c h -t o - c a t c h ) , t h e s t r o k e r a t e , the average power of each s t r o k e , and an e s t i m a t e d 2000 m r a c e time a r e p r e s e n t e d i n T a b l e 5. Powers c a l c u l a t e d f o r the d r i v e phase of some of the s c u l l i n g s t r o k e s i n t h i s paper ( i n d i c a t e d by "*") a r e h i g h e r than the average power e s t i m a t e d f o r maximal rowing ergometer t e s t s of American n a t i o n a l - team c a n d i d a t e s . Hagerman e t a l . , (1978) r e p o r t average power i n 310 s u b j e c t s , of 360113.8 W, w i t h a maximal v a l u e of 407 W, c a l c u l a t e d from the number of f l y w h e e l r e v o l u t i o n s i n 6 min maximal rowing ergometer t e s t s . The average power r e q u i r e d t o s c o r e 5000 f l y w h e e l r e v o l u t i o n s w i t h the G j e s s i n g RE used i n t h i s s t u d y i s s l i g h t l y g r e a t e r than 30 400 W (1 r e v o l u t i o n = 29.4 J , time=360 s ) . The main d i f f e r e n c e between t h e powers shown i n t h i s paper and th o s e e s t i m a t e d i n p r e v i o u s rowing ergometer t e s t s may be due t o the l a c k of a t o t a l m e c h a n i c a l work measure i n the ergometer t e s t s ( i . e., o n l y the e f f o r t a p p l i e d t o the f l y w h e e l has been measured i n the p a s t ) , and t o the absence of any p r e v i o u s e s t i m a t e s of the i n t e r n a l work and the i n t r a - s t r o k e work of ro w i n g . A m e c h a n i c a l energy s t u d y of REs i s r e q u i r e d w i t h a measure of the a n g u l a r v e l o c i t y of the RE's f l y w h e e l b e f o r e c o r r e c t c o n t r a s t s may be drawn between the m e c h a n i c a l energy p a t t e r n s of s c u l l i n g and rowing an RE. The methods used t o e s t i m a t e the average power i n the s h e l l f o r the e n t i r e s t r o k e (average power = (P x ( s t r o k e r a t e ) ) / 6 0 s) d i n c l u d e s b o t h the work r e q u i r e d t o move the s c u l l e r ' s body t h r o u g h t h e rowing s t r o k e and t h e e f f e c t s of the s u b j e c t ' s e f f o r t s on the v e l o c i t y of the r a c i n g s h e l l . B oth of the e s t i m a t e d average powers f o r s u b j e c t 1 s c u l l i n g a t 32 s t r o k e s per minute ( t r i a l s RB1B2 and RB1C3) a r e g r e a t e r than the average powers of the b e s t oarsmen r e p o r t e d by Hagerman (e t a _ l ) . , ( 1978). T h i s s u g g e s t s t h a t the average power c a l c u l a t e d from f l y w h e e l ergometry i n rowing f a l l s s h o r t of the r e a l power e x e r t e d i n s c u l l i n g . F u r t h e r study of the power i n rowing i s n e c e s s a r y and s h o u l d i n c l u d e measurement of the f o r c e s a p p l i e d e i t h e r a t the o a r l o c k , the o a r , or the f o o t b o a r d s , as w e l l as s i m u l t a n e o u s f i l m i n g f o r a power a n a l y s i s . Another s u g g e s t i o n i s t h a t f u r t h e r i n v e s t i g a t i o n of the m e c h a n i c a l e n e r g i e s i n rowing a G j e s s i n g RE i s w a r r a n t e d , u s i n g a measure 31 of the i n s t a n t a n e o u s work a p p l i e d t o the f l y w h e e l of the RE, as w e l l as the i n t e r n a l work due t o the s u b j e c t s ' segmental e n e r g i e s . 32 CONCLUSIONS The d a t a p r e s e n t e d above s u p p o r t the f o l l o w i n g c o n c l u s i o n s : 1. Based on the d i f f e r e n c e s between energy s a v i n g s i n the boat and energy s a v i n g s i n the RE c o n d i t i o n s , t h e r e e x i s t s i g n i f i c a n t d i f f e r e n c e s between the movements of the s c u l l e r when s c u l l i n g and tho s e movements when rowing an ergometer. 2. The main d i f f e r e n c e s i n s a v i n g s a re due t o the motion of the boat r e l a t i v e t o the s u b j e c t , which does not oc c u r on a s t a t i o n a r y RE. 3. The t o t a l body m e c h a n i c a l energy and i n t e r n a l work of rowing a r a c i n g s h e l l i s g r e a t e r than t h a t of rowing a rowing ergometer. 4. S i n c e the t o t a l energy s a v i n g s t h r o u g h exchanges and c o n v e r s i o n s i n the wheeled RE a r e g r e a t e r than those i n the s t a t i o n a r y ergometer, t h e r e i s support f o r a p r o p o s a l t h a t f u t u r e t e s t i n g of oarsmen be co n d u c t e d u s i n g some form of wheeled c a r t under the RE t o p e r m i t use of h i g h e r , more r a c e -l i k e s t r o k e r a t e s i n ergometer t e s t i n g . Recommendations Based on the u n d e r s t a n d i n g g a i n e d w i t h the f i n d i n g s of t h i s s t u d y , the f o l l o w i n g recommendations f o r the study of rowing b i o m e c h a n i c s a r e w a r r a n t e d . 1. The c o m b i n a t i o n of f i l m s t u d y and f o r c e r e c o r d i n g i n the o a r l o c k or the oar would p e r m i t f u r t h e r u n d e r s t a n d i n g of the m e c h a n i c a l energy changes and power f l o w s between the oarsman 33 and t h e b o a t . 2. A moving camera system, t o p e r m i t l a r g e r image s i z e s , i s n e c e s s a r y f o r t h e r e d u c t i o n of n o i s e i n the f i l m d a t a of r o w i n g , i f a whole s t r o k e i s t o be a n a l y z e d . The Olympic rowing c o u r s e i n M o n t r e a l would be i d e a l f o r such a s t u d y , as s e v e r a l c o n s e c u t i v e s t r o k e s c o u l d be s t u d i e d , perhaps under r a c e c o n d i t i o n s . 3. The changes i n s c u l l i n g t e c h n i q u e t h a t may o c c u r w i t h f a t i g u e d u r i n g a r a c e might be examined by f i l m i n g s t r o k e s a t the s t a r t and a t each 250 or 500 m through t h e r a c e . 4. An i n s t a n t a n e o u s measure of the f l y w h e e l a n g u l a r v e l o c i t y of any rowing ergometer must be i n c l u d e d i n any f u t u r e s t u d y of the m e c h a n i c a l energy and i n t e r n a l work of rowing ergometers. 34 REFERENCES 1. E l f t m a n , H. F o r c e s and energy changes i n the l e g d u r i n g w a l k i n g . Am. J . P h y s i o l . 125:339-356 (1939). 2. Hagerman, F. C , and W. D. Lee. Measurement of oxygen consumption, h e a r t r a t e , and work output d u r i n g rowing Med. S c i . S p o r t s . 3(4):155-160, (1971). 3. Hagerman, F. C , W. A d d i n g t o n , and E. A. G a e n s l e r . A comparison of s e l e c t e d v a r i a b l e s among o u t s t a n d i n g c o m p e t i t i v e oarsmen. J _ S p o r t s Med. Phys. F i t n e s s 12(1 ) : 12-22 ( 1972). 4. Hagerman, F. C , M. D. M c K i r n a n , and J . A. Pompei. Maximal oxygen consumption of c o n d i t i o n e d and u n c o n d i t i o n e d oarsmen. J . S p o r t s Med. Phys. F i t n e s s 15(3):43-48, (1975a) 5. Hagerman, F. C , W. W. A d d i n g t o n , and E. A. G a e n s l e r . Severe s t e a d y s t a t e e x e r c i s e a t sea l e v e l and a t a l t i t u d e i n Olympic oarsmen. Med. S c i . S p o r t s 7(4):275-279 (1975b). 6. Hagerman, F. C , M. C. Connors, J . A. G a u l t , G. R. Hagerman, and W. J . P o l i n s k i . Energy e x p e n d i t u r e d u r i n g s i m u l a t e d r o w i n g . J _ A p p l . P h y s i o l . 45(1):87-93, (1978) . 7. Hagerman, F. C , G. R. Hagerman, and T. C. M i c k l e s o n . P h y s i o l o g i c a l p r o f i l e s of e l i t e r owers. P h y s i c i a n and  S p o r t s m e d i c i n e 7(7):74-83, (1979). 8. Henderson, Y., and H. W. Haggard. The maximum of human power and i t s f u e l . Am. J . P h y s i o l . 72:264-282, (1925). 9. P e z z a c k , J . C , R. W. Norman, and D. A. W i n t e r . An assessment of d e r i v a t i v e d e t e r m i n i n g t e c h n i q u e s used f o r motion a n a l y s i s . J _ Biomechanics 10, 377-382, (1977). 10. P i e r r y n o w s k i , M. R. Energy l e v e l s of human body segments d u r i n g l o a d c a r r i a g e on a t r e a d m i l l . M. Sc. T h e s i s ; U n i v e r s i t y of W a t e r l o o , (1978) 11. P i e r r y n o w s k i , M. R., D. A. W i n t e r , and R. W. Norman. T r a n s f e r s of m e c h a n i c a l energy w i t h i n the t o t a l body and m e c h a n i c a l e f f i c i e n c y d u r i n g t r e a d m i l l w a l k i n g . Ergonomics 23(2):147-156, (1980). 12. P i e r r y n o w s k i , M. R., R. W. Norman, and D. A. W i n t e r . M e c h a n i c a l energy a n a l y s e s of the human d u r i n g l o a d c a r r i a g e on a t r e a d m i l l . Ergonomics 24(1):1-14, (1981). 13. R o b e r t s o n , D. G. E., and D. A. W i n t e r . M e c h a n i c a l energy g e n e r a t i o n , a b s o r p t i o n and t r a n s f e r amongst segments d u r i n g w a l k i n g . J _ Biomechanics 13:845-854, (1980). 35 14. ' W i n t e r , D. A. and D. G. E. R o b e r t s o n . J o i n t t o r q u e and energy p a t t e r n s i n normal g a i t . B i o l o g i c a l C y b e r n e t i c s 29:137-142, (1978). 15. W i n t e r , D. A. A new d e f i n i t i o n of m e c h a n i c a l work done i n human movement. J _ A p p l . P h y s i o l . 4 6 ( 0 : 7 9 - 8 3 , (1979a). 16. W i n t e r , D. A. Biomechanics of Human Movement W i l e y , T o r o n t o , (1979b) 17. W o l t r i n g , H. J . C a l i b r a t i o n and measurement i n 3-d i m e n s i o n a l m o n i t o r i n g of human motion by o p t o e l e c t r o n i c means. I . P r e l i m i n a r i e s and t h e o r e t i c a l a s p e c t s . B i o t e l e m e t r y 2:169-196, (1975). 18. W o l t r i n g , H. J . C a l i b r a t i o n and measurement i n 3-d i m e n s i o n a l m o n i t o r i n g of human motion by o p t o e l e c t r o n i c means. I I E x p e r i m e n t a l r e s u l t s and d i s c u s s i o n . B i o t e l e m e t r y 3:65-97, (1976). 36 APPENDIX _ - DEFINITIONS Rowing Terms. The f o l l o w i n g rowing terms were o p e r a t i o n a l l y d e f i n e d f o r d i s c u s s i o n of rowing a c t i o n s : c a t c h - n o r m a l l y t h a t p a r t of the rowing s t r o k e i n which the rower p u t s the b l a d e p o r t i o n of the o a r ( s ) i n t o the water t o b e g i n p u l l i n g t o p r o p e l the b o a t ; f o r t h i s s t u d y the " c a t c h " was the p o s i t i o n of the rower when he or she was no l o n g e r moving f o r w a r d on the s l i d e d u r i n g r e c o v e r y , and had not y e t s t a r t e d t o move back on the s l i d e i n the d r i v e ( t h i s p o s i t i o n was i d e n t i f i e d by the p o s i t i o n of the oar h a n d l e when i t was a t i t s f u r t h e s t p o i n t from the rower's body, and was n e i t h e r moving f o r w a r d nor backward w i t h r e s p e c t t o the rower. d r i v e - t h a t p a r t of the rowing s t r o k e i n which the rower was p u l l i n g the oar handle w i t h the b l a d e p o r t i o n of the oar s quared, and beneath the s u r f a c e of the w a t e r ; the d r i v e i s the p a r t of the s t r o k e used t o p r o p e l the b o a t . f i n i s h - n o r m a l l y t h a t p a r t of the rowing s t r o k e i n which the rower c o m p l e t e s the d r i v e , s t o p s p u l l i n g the oar h a n d l e ( s ) , removes the b l a d e ( s ) from the w a t e r , and f e a t h e r s the b l a d e ( s ) t o b e g i n the r e c o v e r y ; f o r t h i s s tudy f i n i s h meant the p o s i t i o n of the s u b j e c t when the oar h a n d l e had stopped moving backwards (toward the bow of the boat) a t the end of the d r i v e , and had not s t a r t e d moving f o r w a r d w i t h r e s p e c t t o the rower d u r i n g the r e c o v e r y - the o p p o s i t e end of the s t r o k e from the c a t c h p o s i t i o n . r a t e - or - s t r o k e r a t e - the s t r o k e f r e q u e n c y e x p r e s s e d i n 37 s t r o k e s per minute, eg., "rowing a t 30", "30 s t r o k e s per minute", and " s t r i k i n g 30," and o t h e r s i m i l a r e x p r e s s i o n s a r e c o n s i d e r e d e q u i v a l e n t , r a t e watch - a c a l i b r a t e d stopwatch w h i c h d i s p l a y s the s t r o k e r a t e e x t r a p o l a t e d from the time r e q u i r e d t o complete 3 or 4 s t r o k e s (depending upon the c a l i b r a t i o n of the watch f a c e ) , r e c o v e r y - t h a t p a r t of the rowing s t r o k e f o l l o w i n g the f i n i s h and b e f o r e the c a t c h , when the rower p r e p a r e s f o r the next s t r o k e . s c u l l i n g - r o w i n g i n a boat u s i n g two o a r s ( s c u l l s ) per p e r s o n , one on each s i d e of the boat ( c . f . "sweep"). s h e l l - a boat used f o r f l a t water r a c e rowing - a l s o c a l l e d a " s k i f f " . s l i d e - t h e t h e t r a c k s which g u i d e t h e movement of t h e wheels of the rower's s e a t i n a s h e l l , s t r e t c h e r - the p a r t of the s h e l l used t o p o s i t i o n the rower's f e e t d u r i n g r owing; a l s o c a l l e d " f o o t b o a r d " sweep - rowing i n a boat u s i n g one oar (sweep) on one s i d e of the s h e l l ; sweeps r e q u i r e a minimum of two rowers w h i l e s c u l l i n g may be done a l o n e or w i t h p a r t n e r s . Energy A n a l y s i s Terms. D i s c u s s i o n of m e c h a n i c a l energy i n t h i s s t u d y r e q u i r e d the o p e r a t i o n a l d e f i n i t i o n of the f o l l o w i n g - terms: c o n v e r s i o n - see " i n t e r c o n v e r s i o n " , below. 38 i n t e r c o n v e r s i o n - (energy i n t e r c o n v e r s i o n ) the change i n the e x p r e s s i o n of the m e c h a n i c a l energy w i t h i n a body segment i . e., when an o b j e c t i s dropped from a h e i g h t p o t e n t i a l energy i s c o n v e r t e d or i n t e r c o n v e r t e d t o k i n e t i c energy, exchange - (energy exchange) the t r a n s m i s s i o n of m e c h a n i c a l energy from one body p a r t t o an o t h e r e. g., energy " g e n e r a t e d " i n the a n t e r i o r d e l t o i d muscle by c h e m i c a l r e a c t i o n s between a c t i n , myosin, and adenosine t r i p h o s p h a t e i s t r a n s f e r r e d t o the fo r e a r m segment i n the a c t i o n of s h o u l d e r f l e x i o n ( d e s c r i b e d i n E l f t m a n (1939), W i n t e r and Ro b e r t s o n (1978), and i n Robertson and W i n t e r (1980). Energy i s exchanged among segments when the d e c e l e r a t i o n of one segment causes a c c e l e r a t i o n of an a d j a c e n t or nearby segment. These d e f i n i t i o n s of i n t e r c o n v e r s i o n and exchange of m e c h a n i c a l energy d i f f e r from those p r e v i o u s l y used. C a l d w e l l (1980) used exchange t o d i s c u s s both c o n v e r s i o n and exchange. P i e r r y n o w s k i , e t a l . (1980) used t r a n s f e r t o e x p r e s s the two v a l u e s . The use of two terms whose d i c t i o n a r y d e f i n i t i o n s a r e more s u i t e d t o the d e s c r i p t i o n of d i f f e r e n t e f f e c t s of motion on the m e c h a n i c a l energy of an o b j e c t i s perhaps l e s s ambiguous than u s i n g the same term, whether exchange or t r a n s f e r , t o d i s c u s s d i f f e r e n t s o u r c e s of energy s a v i n g . T h i s may be p a r t i c u l a r l y i m p o r t a n t f o r p e o p l e l e s s f a m i l i a r w i t h the c o n c e p t s and t e r m i n o l o g y of t h i s s t u d y and o t h e r s l i k e i t . work - used t o d e s c r i b e the change i n the t o t a l m e c h a n i c a l energy of a segment or of a body; a l s o c a l l e d pseudowork or i n t e r n a l work; the energy change r e q u i r e d t o move body p a r t s i n space - d i s t i n c t from e x t e r n a l work, which i s the energy 39 change r e q u i r e d t o e f f e c t a change i n the immediate s u r r o u n d i n g s of the body a g a i n s t g r a v i t y . 40 APPENDIX 2 - SYMBOLS USED IN THE PAPER E - k i n e t i c energy k E - t r a n s l a t i o n a l k i n e t i c energy kt E - r o t a t i o n a l k i n e t i c energy kr E - p o t e n t i a l energy P P - average power i n the d r i v e phase of a s t r o k e d S - energy "saved" by exchange among segments e x p r e s s e d as a e pe r c e n t a g e of the t o t a l m e c h a n i c a l work r e q u i r e d w i t h n e i t h e r exchange nor c o n v e r s i o n of m e c h a n i c a l energy. S - energy "saved" by i n t e r c o n v e r s i o n w i t h i n segments, i e x p r e s s e d as a p e r c e n t a g e of the t o t a l m e c h a n i c a l work r e q u i r e d w i t h n e i t h e r exchange nor c o n v e r s i o n of m e c h a n i c a l energy. W - work r e q u i r e d t o move the segments of the body i f exchange e of energy was p e r m i t t e d , but i n t e r c o n v e r s i o n of energy was not p e r m i t t e d . ( E q u a t i o n #5) W - work r e q u i r e d t o move the segments of the body a l l o w i n g i b o t h exchange and i n t e r c o n v e r s i o n of m e c h a n i c a l energy ( E q u a t i o n #4) W - Work r e q u i r e d t o move the segments of the body i f n e i t h e r n exchange nor i n t e r c o n v e r s i o n of energy was p e r m i t t e d ( E q u a t i o n #6). 41 APPENDIX 3 - ENERGY PLOTS OF SUBJECTS 2. 3. AND 4 42 TOTAL BODY AND TORSO+THIGHS KINETIC ENERGY SUBJECT 2 400 _L 0.00 0.25 0.50 FIGURE 4 . 0 . 7 5 I'.OO 1.25 1.50 1.75 TIME [SECONDS] 2.00 2.25 2.50 2. 43 TOTAL BODY AND TORSO+THIGHS KINETIC ENERGY SUBJECT 3 TRIAL CODE: SUBJ 3 FIGURE 5. TIME (SECONDS) 44 flnn TOTAL BODY AND TORSO+THIGHS KINETIC ENERGY SUBJECT 4 o.oa 0 . 2 5 FIGURE 6. 0 . 7 5 1.00 1.25 1.50 TIME ISECONDS) 45 APPENDIX 4 - REVIEW OF LITERATURE The s t u d y of the m e c h a n i c a l energy v a r i a t i o n s of rowing r e q u i r e s f a m i l i a r i t y w i t h t h r e e a r e a s i n the l i t e r a t u r e : a nthropometry as a p p l i e d t o human movement, m e c h a n i c a l energy s t u d i e s of human movement, and m e c h a n i c a l a s p e c t s of the rowing s t r o k e . T h i s r e v i e w c o n t a i n s a b r i e f s u r v ey some commonly used anthropometry s t u d i e s and a s h o r t r e v i e w of some r e c e n t s t u d i e s of the i n e r t i a l p r o p e r t i e s of human body segments. As w e l l , an e f f o r t has been made t o su r v e y the development of the m e c h a n i c a l energy methods used i n t h i s s t u d y , w i t h the aim of f o l l o w i n g the development of t h e s e methods r a t h e r than l i s t i n g e v e r y paper r e p o r t i n g use of t h e s e methods. The s e c t i o n on the mechanics of rowing i s i n c o m p l e t e , as most of the r e p o r t s p u b l i s h e d on m e c h a n i c a l a s p e c t s of rowing a r e more s u b j e c t i v e than s c i e n t i f i c . The aim i n the rowing s e c t i o n of t h i s r e v i e w was t o be as complete as p o s s i b l e i n s u r v e y i n g the E n g l i s h language m a t e r i a l u s i n g o b j e c t i v e measures of m e c h a n i c a l a s p e c t s of ro w i n g . Anthropometry The s t u d y of the m e c h a n i c a l p r o p e r t i e s of human movement r e q u i r e s a knowledge of or a model d e s c r i b i n g the mass d i s t r i b u t i o n and i n e r t i a l p r o p e r t i e s of the body and i t s segments. There have been r e l a t i v e l y few s t u d i e s of the i n e r t i a l p r o p e r t i e s of the human body, m a i n l y because of the c o m p l e x i t y of such s t u d i e s and the d i f f i c u l t y i n o b t a i n i n g good sample d i s t r i b u t i o n s r e p r e s e n t a t i v e of the human p o p u l a t i o n ( C h a n d l e r , e t a l . 1975; M c C o n v i l l e , e t a l . 1980). 46 The c e n t r e of g r a v i t y (CG) i s measured i n a number of ways, i n c l u d i n g r e a c t i o n b oards, b a l a n c e b o a r d s , and " g r a v i t y l i n e s " ( i . e., l o c a t i n g the e.g. a t the i n t e r s e c t i o n of v e r t i c a l l i n e s drawn down from 3 or more d i f f e r e n t p o i n t s of s u s p e n s i o n ) . Moments of i n e r t i a can be measured i n a few segments i n l i v e s u b j e c t s by h o l d i n g the segment a g a i n s t a maximal c o n t r a c t i o n , r e l e a s i n g the segment s u d d e n l y , measuring the a c c e l e r a t i o n of the segment i m m e d i a t e l y a f t e r r e l e a s e , and u s i n g the a p p r o p r i a t e c o m p u t a t i o n . The u s u a l method f o r whole body and cadaver segment study i s t h a t of the compound pendulum, which i n v o l v e s "suspending the body [or segment] from some f i x e d p o i n t [which may be e x t e r n a l t o the o b j e c t ] , s e t t i n g i t i n motion by s h i f t i n g i t a few degrees from i t s e q u i l i b r i u m p o s i t i o n , and d e t e r m i n i n g i t s p e r i o d of o s c i l l a t i o n . . . " (Hay, 1974). T h i s p e r i o d i s then e n t e r e d i n the e q u a t i o n : I = WhT 2/4 ( 7 r ) 2 o where -(I i s the moment of i n e r t i a of the body or p a r t about an o a x i s t h r o u g h the p o i n t of s u s p e n s i o n 0, W i s the weight of the body or p a r t , h i s the d i s t a n c e from 0 t o the CG of the o b j e c t , and T i s the p e r i o d of o s c i l l a t i o n . Two o t h e r v a l u e s , the moment of i n e r t i a about the CG (I ) and eg the r a d i u s of g y r a t i o n (k) may be c a l c u l a t e d u s i n g : I = 1 - mh 2, and eg o k = s q r t d /m) o o 47 where m i s the mass of the o b j e c t . Braune and F i s c h e r (1889) and F i s c h e r (1906) p r e s e n t e a r l y s t u d i e s of the CG and of t h e moments of i n e r t i a , r e s p e c t i v e l y , of human c a d a v e r s and cadaver segments. These German language papers have been summarized and a b r i d g e d by Krogman and J o h n s t o n (1963) and r e v i e w e d by Hay (1973,1974). The Braune and F i s c h e r d a t a and the F i s c h e r d a t a have been used i n a number of e a r l y b i o m e c h a n i c s s t u d i e s e. g., Fenn (1930) and E l f t m a n (1939). Use of the Braune and F i s c h e r (1889) and the F i s c h e r (1906) d a t a f o r s t u d y i n g the k i n e t i c p r o p e r t i e s of human motion ( p a r t i c u l a r l y i n a t h l e t e s ) i s not recommended f o r a number of r e a s o n s . F i r s t , the c a d a v e r s used by Braune and F i s c h e r were g e n e r a l l y s m a l l i n s t a t u r e , w h i l e the one cadaver used by F i s c h e r i n 1906 was v e r y s m a l l (44.057 kg, and 150.5 cm) (Krogman and J o h n s t o n , 1963). Second, the c a d a v e r s used i n the e a r l i e r s tudy were not p o s i t i o n e d a c c u r a t e l y ; the saw c u t s used t o segment the s u b j e c t s were thus i n a c c u r a t e due t o the i n c o n s i s t e n t p o s i t i o n i n g of the c a d a v e r s (Hay, 1973). The next major study of the mass d i s t r i b u t i o n and i n e r t i a i p r o p e r t i e s of humans i s t h a t of Dempster (1955). That paper has a l s o been condensed by Krogman and J o h n s t o n (1963), and reviewed by Hay (1973,1974). Dempster's study i n c l u d e d the CG of the body and i t s segments, the r a t i o s of d i s t a n c e between the CG and each segment's ends, the mass f r a c t i o n s of the segments (segment mass / t o t a l -body mass), and moments of i n e r t i a and r a d i i of g y r a t i o n of each segment s t u d i e d . Dempster's seven c a d a v e r s were s m a l l e r , l i g h t e r , and o l d e r (the youngest l i s t e d cadaver age was 52) than the average w h i t e male or m i l i t a r y p e r s o n n e l 48 (Dempster, 1955). Dempster's d a t a have been used t o r e p l a c e t h a t of Braune and F i s c h e r , but a r e s t i l l not r e p r e s e n t a t i v e of the p o p u l a t i o n of a t h l e t e s from which the sample i n t h i s s t u d y was drawn. Hay (1974) s u g g e s t s t h a t d a t a f o r the cadaver i n Dempster's t a b l e s of d a t a most n e a r l y matched w i t h each s u b j e c t be used f o r k i n e t i c s s t u d i e s , r a t h e r than average d a t a . More r e c e n t s t u d i e s i n t h i s a r e a have s t u d i e d the i n e r t i a l p r o p e r t i e s of humans w i t h the aim of p r o v i d i n g r e l i a b l e and v a l i d r e g r e s s i o n e q u a t i o n s f o r the e s t i m a t i o n of i n d i v i d u a l s u b j e c t i n f o r m a t i o n . F u t u r e r e s e a r c h i n the k i n e m a t i c s and k i n e t i c s of humans s h o u l d attempt t o use t h i s new i n f o r m a t i o n t o d e s c r i b e the i n e r t i a l p r o p e r t i e s of i n d i v i d u a l s u b j e c t s . S e v e r a l s t u d i e s have been completed of the mass d i s t r i b u t i o n and the i n e r t i a l p r o p e r t i e s of the human body s i n c e Dempster's. Most worthy of note a r e those of C l a u s e r , e t a l . (1969), C h a n d l e r , e t a l . (1975), and M c C o n v i l l e , e t a l . (1980). C l a u s e r , e t a l , (1969) s t u d i e d the l o c a t i o n of the CG i n 13 embalmed c a d a v e r s , i n two s e p a r a t e p l a n e s ( i n most segments). The p o s i t i o n of the segmental CGs were g i v e n as p r o p o r t i o n s of the d i s t a n c e between segment ends, and between c e r t a i n a n t e r i o r and p o s t e r i o r landmarks. Data from t h a t s t u d y were q u i t e s i m i l a r t o those of Dempster's (1955). The main d i f f e r e n c e between C l a u s e r , e t a l _ . , (1976) and Dempster was i n the mass f r a c t i o n s r e p r e s e n t e d by the head segment and by the t o r s o segments. These d i f f e r e n c e s a r e p r o b a b l y due t o C l a u s e r e t a l . h a v i n g used a h i g h e r p o s i t i o n on the neck t o s e p a r a t e the two segments than d i d Dempster. 49 C h a n d l e r , e t a l . (1975), p r o v i d e a t h r e e - d i m e n s i o n a l s t u d y of the i n e r t i a l p r o p e r t i e s of s i x f r o z e n embalmed male c a d a v e r s . The s m a l l sample s i z e , and the use of two groups of t h r e e c a d a v e r s i n d i f f e r e n t p o s i t i o n s reduced the a c c u r a c y of the proposed model. C h a n d l e r et a_l. s t a t e , almost c a t e g o r i c a l l y , t h a t the d a t a and r e g r e s s i o n e q u a t i o n s p r e s e n t e d are not r e f l e c t i o n s of the p o p u l a t i o n of a d u l t males, and s h o u l d not be used as such. M c C o n v i l l e , e t a_l. ( 1980) s t u d i e d 31 l i v i n g males u s i n g s t e r e o m e t r i c photography t o a s s e s s t o t a l body and segmental moments of i n e r t i a i n t h r e e axes. The compound pendulum method was used as c r i t e r i o n t o a s s e s s the a c c u r a c y of the s t e r e o m e t r i c measure f o r t o t a l body moments. ( A c c o r d i n g t o t h o s e a u t h o r s , i f the pendulum method and the p h o t o g r a p h i c method had not a g r e e d i n a t r i a l s u b j e c t , the s t u d y may not have been completed.) T h i s appears t o be the f i r s t s t u d y u s i n g a n a t o m i c a l landmarks t o d e f i n e the p r i n c i p a l axes f o r the moment of i n e r t i a , r a t h e r than u s i n g some p r i n c i p a l a x i s system e x t e r n a l t o the segment b e i n g s t u d i e d . In a l l segments except t h e head and t h e neck, th e r e g r e s s i o n e q u a t i o n s d e v e l o p e d t o p r e d i c t the moments about th e p r i n c i p a l x-, y-, and z-axes were s i g n i f i c a n t l y more a c c u r a t e than the mean v a l u e s , as i n d i c a t e d by reduced s t a n d a r d e r r o r s of e s t i m a t e compared w i t h the s t a n d a r d d e v i a t i o n s of the moments' means. The main f a u l t w i t h t h i s s t u d y was t h a t the o r i g i n of the p r i n c i p a l axes was l o c a t e d a t the segmental c e n t r e s of volume, u s u a l l y found d i s t a l t o the c e n t r e of mass, w h i l e the mass c e n t r e i s the u s u a l p o s i t i o n about which i n e r t i a l p r o p e r t i e s a r e s t u d i e d ( M c C o n v i l l e , e t a l . , 1980). 50 Energy and Work E a r l y r e p o r t s d e s c r i b i n g m e c h a n i c a l energy i n human motion a r e those of Fenn (1930), and E l f t m a n (1939). Fenn used h i g h -speed f i l m i n g t o study the changes i n the k i n e t i c energy of the body and i t s segments i n s p r i n t i n g . The s u b j e c t s ' b o d i e s were used as r e f e r e n c e p o i n t s f o r the segmental motions t o s i m p l i f y t h e c a l c u l a t i o n of changes i n the KE of the arms and l e g s , and t o t r y t o e l i m i n a t e c a l c u l a t i o n of energy exchanges from body t o l i m b s or from l i m b s t o body. The c a l c u l a t e d work v a l u e was e x t r e m e l y h i g h s i n c e no a l l o w a n c e was made f o r t r a n s f e r s or exchanges of energy. Cavagna, e t a_l. ( 1 964) s t u d i e d r u n n i n g , r e c o r d i n g from a t r i - a x i a l a c c e l e r o m e t e r p l a c e d near the CG. A c c e l e r a t i o n s were i n t e g r a t e d w i t h r e s p e c t t o time t o o b t a i n the v e l o c i t y of t h e CG. V e l o c i t y d a t a were then used i n c a l c u l a t i n g the k i n e t i c energy of the t r u n k . Cavagna e t a l . (1964) a l s o s t u d i e d the e n e r g i e s of the l i m b s w i t h the t r u n k as a r e f e r e n c e " p o i n t " . F l a w s i n the use of t r u n k a c c e l e r a t i o n d a t a t o d e r i v e t o t a l body energy p a t t e r n s (e. g., Cavagna, e t a l . , (1964); Gage, ( 1964); G e r s t e n , e t a l . , (1969)) a r e d i s c u s s e d l a t e r i n t h i s r e v i e w ( W i n t e r , 1979). Other s t u d i e s have used f o r c e p l a t e s t o s t u d y th e v e l o c i t y as d e r i v e d from f o r c e s (hence a c c e l e r a t i o n s ) t o c a l c u l a t e KE (eg . , Cavagna and M a r g a r i a (1966), Cavagna, e t a l . , ( 1 971,1976)). The problems a s s o c i a t e d w i t h t h i s approach a r e s i m i l a r t o those a s s o c i a t e d w i t h u s i n g the a c c e l e r a t i o n of the CG f o r energy assessment. Both the Fenn (1930) and the Cavagna (1964) r e p o r t s e s t i m a t e the KE of the l i m b s i n c o r r e c t l y . Smith 51 (1975) i n d i c a t e s t h a t Fenn's c a l c u l a t i o n s a p p l y o n l y when the segmental v e l o c i t y i s p e r p e n d i c u l a r t o t h a t of the body, a r a r e o c c u r r e n c e , and t h a t a b s o l u t e segmental v e l o c i t y ( b o t h v e r t i c a l and h o r i z o n t a l components, i n a two d i m e n s i o n a l s t u d y ) must be used t o c a l c u l a t e the KE of a l i m b o r segment. In a c l a s s i c s tudy of the k i n e t i c s and k i n e m a t i c s of w a l k i n g , E l f t m a n (1939) s y n c h r o n i z e d f o r c e - p l a t e d a t a w i t h f i l m d a t a t o examine the r a t e s of t r a n s f e r of m e c h a n i c a l energy among segments. Energy exchange was not s t u d i e d . R e p l i c a t i o n of E l f t m a n ' s s t u d y i s d i f f i c u l t , because t h e r e i s no i n d i c a t i o n of the formulae used t o compute the energy-time p a t t e r n s . The c h i e f h i n d r a n c e t o E l f t m a n was the need t o use manual t e c h n i q u e s t o d i f f e r e n t i a t e d i s p l a c e m a n t d a t a t o o b t a i n segment v e l o c i t y and a c c e l e r a t i o n i n f o r m a t i o n from the f i l m . These manual t e c h n i q u e s a l s o a f f e c t e d the a c c u r a c y of Fenn's s t u d y . I n t r o d u c t i o n of computer t e c h n o l o g y t o g a i t s t u d i e s has g r e a t l y i n c r e a s e d the q u a n t i t y , and, i t i s hoped the q u a l i t y , of d a t a t h a t can be s t u d i e d . E r r o r s a s s o c i a t e d w i t h manual d a t a c o l l e c t i o n have a l s o been reduced, by r e d u c i n g the o p p o r t u n i t y f o r humans t o c o l l e c t d a t a . The c h i e f r e m a i n i n g s o u r c e of human e r r o r i s now a t the s t a g e of f i l m d a t a c o l l e c t i o n ( W i n t e r , e t a l . ( 1 9 74), P e z z a c k , e t a l . ( 1 9 7 7 ) ) . Quanbury, W i n t e r , and Reimer (1975) s t u d i e d the m e c h a n i c a l energy p a t t e r n s i n w a l k i n g , u s i n g a t e l e v i s i o n - c o m p u t e r i n t e r f a c e t o c o l l e c t raw k i n e m a t i c d a t a a u t o m a t i c a l l y . J o i n t f o r c e s and power f l o w s were computed f o r a l l segments, s t a r t i n g w i t h the s w i n g i n g l e g , and wo r k i n g back t h r o u g h the p e l v i s t o t h e s u p p o r t i n g l e g . These c a l c u l a t i o n s were done o n l y f o r the s i n g l e l e g s u p p o r t phase of 52 the w a l k i n g s t r i d e . An e s t i m a t e of ground r e a c t i o n f o r c e (GRF) t o the s u p p o r t i n g f o o t was computed. I t may be t h e o r e t i c a l l y p o s s i b l e t o c a l c u l a t e GRF from k i n e m a t i c d a t a , but the human body i s not i d e a l l y s u i t e d t o the a n a l y s i s , as i t v i o l a t e s the assumptions of the l i n k - s e g m e n t model i n a number of ways. Quanbury, e t a l . (1975) were unable t o c o r r o b o r a t e t h e i r c a l c u l a t e d GRF w i t h r e a l f o r c e p l a t e d a t a . Smith (1975) c o n t r a s t e d the use of a b s o l u t e v e l o c i t y and the r o t a t i o n a l v e l o c i t y of segments w i t h Fenn's (1930) method of c a l c u l a t i n g KE, i n s t u d y i n g a jumping movement. I t was shown t h a t Fenn's method ( a l s o used by Cavagna, e t a l . (1964)) was i n s e n s i t i v e t o a s i g n i f i c a n t amount of the KE p r e s e n t i n most human movements, as i t was o n l y v a l i d a t the v e r y r a r e i n s t a n c e when a segment's v e l o c i t y was p e r p e n d i c u l a r t o the body's v e l o c i t y . Norman, et §_. (1976) c o i n e d the term " m e c h a n i c a l pseudowork" t o d e s c r i b e the changes i n m e c h a n i c a l energy of the l i m b s and segments d u r i n g w a l k i n g . Pseudowork was computed as the sum of the a b s o l u t e v a l u e s of a l l p o t e n t i a l and k i n e t i c energy changes, f o r a l l segments i n a l i n k - s e g m e n t model, f o r a l l of the time i n t e r v a l s ( f i l m frames) i n c l u d e d i n the movement. T h i s "pseudowork" i s e q u i v a l e n t t o the term "W " n ( e q u a t i o n #6), used i n the p r e s e n t s t u d y . U s i n g the a b s o l u t e v a l u e s of a l l i n t r a - s e g m e n t energy changes, as i n Wn, c r e a t e s an a r t i f i c i a l l y h i g h "work" term. W i n t e r , (1979) expanding on the concept of pseudowork, d e f i n e s " i n t e r n a l " work of human movement as a l l p o t e n t i a l and k i n e t i c energy changes t h a t o c c u r i n a l l segments of the body d u r i n g movement. The d i s t i n c t i o n drawn between i n t e r n a l and 53 e x t e r n a l work i s t h a t e x t e r n a l work i s a measure of movement of an o b j e c t ( the body) through some v e r t i c a l d i s p l a c e m e n t i . e., a change i n PE or an i n c r e a s e i n v e l o c i t y ; i n t e r n a l work i s a measure of the energy changes (PE and KE) o c c u r i n g i n a l l segments w h i l e moving, perhaps d u r i n g e x t e r n a l work. I n t e r n a l work i s the sum of the t o t a l m e c h a n i c a l e n e r g i e s of a l l segments, i n a l l time i n t e r v a l s of a movement. T h i s c a l c u l a t i o n d i f f e r s from pseudowork (Norman, e t a l . (1976) i n t h a t i n t e r n a l work i s the "raw" sum of the energy changes, w h i l e pseudowork i s the sum of the a b s o l u t e v a l u e s of those energy changes. The t r i a n g l e i n e q u a l i t y (|a+b| ^ |a|+|b|) d i c t a t e s t h a t i n t e r n a l work i s always l e s s than or ( r a r e l y ) e q u a l t o pseudowork. W i n t e r ' s (1979) term " i n t e r n a l work" i s e q u i v a l e n t t o the W i computed e a r l i e r i n t h i s paper ( e q u a t i o n #4). A minor problem i n the c a l c u l a t i o n s p r e s e n t e d by Win t e r i s t h a t , a l t h o u g h the e x t e r n a l work i s assumed t o e q u a l z e r o the d i g i t i z i n g p r o c e s s u s u a l l y i n t r o d u c e s some s m a l l amount of e x t e r n a l work. T h i s o c c u r s when the t o t a l body energy a t the end of a movement c y c l e i s d i f f e r e n t from t h a t a t the b e g i n n i n g of t h e c y c l e . O f t e n , i n c o n t r o l l e d s i t u a t i o n s , the e r r o r i s due t o s m a l l e r r o r s ( n o i s e ) i n t he d i g i t i z e d d a t a , i n t r o d u c e d by the human o p e r a t i n g the d i g i t i z e r . T h i s e r r o r was r e c o g n i z e d and c o r r e c t e d f o r by P i e r r y n o w s k i , e t a l . (1980). W i n t e r ' s i n t e r n a l work term i s c r e d i t e d w i t h i d e n t i f y i n g changes i n the m e c h a n i c a l energy of the body and segments which a r e not d e t e c t e d by s t u d y i n g t h e motion of t h e t o t a l body CG. Movement of the l i m b s i n r e c i p r o c a l movements such as w a l k i n g and r u n n i n g r e q u i r e s some work from the m u s c l e s , a l o n g w i t h 54 p a s s i v e energy changes. M o t i o n s of the l i m b s a r e not d e t e c t e d by f o l l o w i n g the CG, as i n Cavagna, et a l . (1964). W i n t e r (1979) compared the energy p a t t e r n s of the CG w i t h the i n t e r n a l work (W ) of the body, and showed t h a t the CG "work" i u n d e r e s t i m a t e d the a c t u a l m e c h a n i c a l work of w a l k i n g (measured w i t h the method f o r W , t h i s paper) by 16 t o 40 p e r c e n t . i P i e r r y n o w s k i , W i n t e r , and Norman (1980) f u r t h e r adapted the c a l c u l a t i o n s of the energy a n a l y s i s . The "work" c a l c u l a t i o n was f u r t h e r p a r t i t i o n e d t o p e r m i t ( m a t h e m a t i c a l l y ) the exchange of energy w i t h i n segments, but not the t r a n s f e r of energy among segments. T h i s was done by a d d i n g the a b s o l u t e v a l u e s of the " i n s t a n t a n e o u s " changes of the segment t o t a l e n e r g i e s . The e q u i v a l e n t c a l c u l a t i o n i s t h a t of "W " ( e q u a t i o n #5, t h i s e p a p e r ) . P i e r r y n o w s k i , e t a l . (1980) then removed apparent e x t e r n a l work (W , e q u a t i o n #3, t h i s p a p e r ) , and c a l c u l a t e d t energy t r a n s f e r s and exchanges by s u b t r a c t i o n of the a p p r o p r i a t e "work" terms. P i e r r y n o w s k i , e_t a l . , ( 1980) a l s o c a l c u l a t e d an e f f i c i e n c y term, a t t e m p t i n g t o account f o r i n t e r n a l work, e x t e r n a l work, and t h e d i f f e r e n t e f f i c i e n c i e s of c o n c e n t r i c and e c c e n t r i c m u scular c o n t r a c t i o n . The c h o i c e of the numbers used t o r e p r e s e n t the m e t a b o l i c e f f i c i e n c i e s of the d i f f e r e n t c o n t r a c t i o n s appears t o have been somewhat a r b i t r a r y , however, and i s open t o q u e s t i o n . R o b e r t s o n and W i n t e r (1980) s t u d i e d j o i n t and muscle powers, and segmental energy p a t t e r n s of the lower l i m b i n 55 normal w a l k i n g . The l i n k - s e g m e n t model and f i n i t e d i f f e r e n c e a r i t h m e t i c were used t o d e r i v e i n s t a n t a n e o u s m e c h a n i c a l energy from f i l m d a t a . A f o r c e p l a t e was used i n c o n j u n c t i o n w i t h the f i l m d a t a t o study the j o i n t powers. T o t a l power and segmental energy c u r v e s were v e r y s i m i l a r f o r the e n t i r e s t r i d e i n the t h i g h and shank segments, and f o r most of the s t r i d e i n the f o o t . The f o o t segment e n e r g i e s showed l i t t l e change t h r o u g h the e n t i r e s t e p c y c l e , w h i l e the a n k l e j o i n t powers v a r i e d c o n s i d e r a b l y a t the weight a c c e p t a n c e and p u s h - o f f s t a g e s of the s t e p . T h i s d i f f e r e n c e between power and energy r e s u l t s f o r the f o o t was a t t r i b u t e d t o the l a r g e j o i n t power and muscle power components ( o p p o s i t e i n s i g n ) , where a s m a l l e r r o r i n measurement would cause c o n s i d e r a b l e change i n the t o t a l power d e l i v e r e d t o the f o o t . P i e r r y n o w s k i , Norman and W i n t e r , (1981) a p p l i e d the energy c a l c u l a t i o n s t o the s t u d y of l o a d c a r r i a g e on a t r e a d m i l l . One of the c o n c l u s i o n s of t h a t study was t h a t the methods p r e v i o u s l y used t o s t u d y normal and p a t h o l o g i c a l w a l k i n g c o u l d be a p p l i e d t o the study of l o a d c a r r i a g e and p o s s i b l y t o s t u d y of backpack d e s i g n . Another study u s i n g these methods f o r o t h e r forms of l o c o m o t i o n i s t h a t of C a l d w e l l (1980). C a l d w e l l s t u d i e d the m e c h a n i c a l c o s t and the energy t r a n s f e r s (and exchanges) i n two l e v e l s of c r o s s - c o u n t r y s k i e r s . More s k i l l e d ( i n t e r n a t i o n a l l y c o m p e t i t i v e ) s k i r a c e r s were found t o exchange and t r a n s f e r a g r e a t e r p r o p o r t i o n of the t o t a l "pseudowork" than n o v i c e s . Problems a s s o c i a t e d w i t h s t a t i o n a r y cameras o u t s i d e of the l a b o r a t o r y were i d e n t i f i e d a s : - c a m era-object d i s t a n c e has t o be l a r g e . 56 - a wide f i e l d of view i s needed t o ensure f i l m i n g a t l e a s t one complete movement c y c l e , - the two r e s t r i c t i o n s above combine t o g i v e v e r y s m a l l image s i z e , t h u s a low s i g n a l : n o i s e r a t i o ; In the p r e s e n t study the a c c u r a c y of the d i g i t i z i n g was r e s t r i c t e d as the p r o j e c t e d ( d i g i t i z e d ) image was o n l y about 3% l i f e s i z e . Komi, e t a l . , (1981) s t u d i e d the m e c h a n i c a l energy of n i n e r u n n e r s a t the speeds a t which b l o o d l a c t a t e b e g i n s t o a c c u m u l a t e . H i g h c o r r e l a t i o n s were found between the average power ou t p u t a t the measured v e l o c i t i e s and the p e r c e n t a g e of s l o w - t w i t c h muscle f i b r e s measured from b i o p s i e s of the v a s t u s l a t e r a l i s m u s c l e . S u b j e c t s were not t e s t e d , nor were m e c h a n i c a l e n e r g i e s a s s e s s e d a t r u n n i n g speeds o t h e r than the l a c t a t e " t h r e s h o l d " . F u t u r e r u n n i n g s t u d i e s w i t h m e t a b o l i c and energy measures s h o u l d t e s t a t a v a r i e t y of speeds i n each s u b j e c t , t o t e s t f o r f u r t h e r r e l a t i o n s h i p s between the m e c h a n i c a l and m e t a b o l i c f e a t u r e s of r u n n i n g . Mechanics and Rowing Few E n g l i s h - l a n g u a g e s t u d i e s e x i s t i n the m e c h a n i c a l a s p e c t s of r o w i n g . A s e a r c h of the l i t e r a t u r e found no s t u d i e s u s i n g the m e c h a n i c a l energy approach t o study the rowing s t r o k e c y c l e . Most e x i s t i n g l i t e r a t u r e on the mechanics or 57 b i o m e c h a n i c s of rowing c o n s i d e r hydrodynamics, boat and equipment d e s i g n f o r c e a t the o a r - h a n d l e (and c o n s e q u e n t l y , a t the b l a d e ) , or the e f f e c t s of s t r o k e r a t e on s h e l l v e l o c i t y . Most o t h e r l i t e r a t u r e (not r e p o r t e d here) c o n t a i n s r e l a t i v e l y s u b j e c t i v e o b s e r v a t i o n s of the k i n e m a t i c s of r o w i n g . A r e c e n t l y p u b l i s h e d r e v i e w of p h y s i o l o g i c a l and b i o m e c h a n i c a l a s p e c t s of rowing and p a d d l i n g s p o r t s i s u s e f u l as i t d i s c u s s e s some of the non E n g l i s h - l a n g u a g e papers on rowing ( Z s i d e g h , 1981). The e f f e c t of s t r o k e r a t e upon impulse ( i n each s t r o k e and over a timed i n t e r v a l ) , and s t u d i e s on s t r o k e t e c h n i q u e , f o r c e development, and r i g g i n g a r e mentioned. Z s i d e g h ' s r e v i e w i s u s e f u l f o r g u i d i n g a s e a r c h of the non-E n g l i s h work on the mechanics of r o w i n g . W i l l i a m s (1967) d e s c r i b e s the " i d e a l " motions r e q u i r e d of the oarsman i n t a k i n g a s t r o k e , and d i s c u s s e s the t i m i n g of the power a p p l i c a t i o n i n a rowing s t y l e not common i n modern r o w i n g . Cameron (1967) e v a l u a t e d s h e l l d e s i g n , oar s t i f f n e s s , and o t h e r s t r u c t u r a l a s p e c t s of rowing equipment; l i t t l e a t t e n t i o n was p a i d t o a c t u a l l y u s i n g the equipment. W e l l i c o m e (1967) e v a l u a t e d the v a r i o u s e f f e c t s of water d e p t h , boat b r e a d t h ( w i d e s t p o i n t ) and l e n g t h , oar d e s i g n , s h e l l c r o s s - s e c t i o n , s u r f a c e roughness, v i s c o u s d r a g , and wave dynamics on the r e l a t i v e v e l o c i t y of a rowing s h e l l . Pope (1973) d e s i g n e d a t h e o r e t i c a l model t o i n c l u d e f o r c e a t the o a r , power a p p l i c a t i o n w i t h r e s p e c t t o t h e p o s i t i o n of the o a r l o c k , and o t h e r f a c t o r s . The model s i m p l i f i e d t he e f f e c t s of asymmetric f o r c e a p p l i c a t i o n ( c a u s i n g yaw), and of the movement of the system's t o t a l CG d u r i n g the s t r o k e . Some 58 i n s i g h t s were g a i n e d r e g a r d i n g the p o t e n t i a l e f f e c t i v e n e s s of changes i n the p o s i t i o n of the o a r l o c k r e l a t i v e t o the p o s i t i o n of the f r o n t of the s l i d e . Pope appears t o r e c o g n i z e numerous human f a c t o r s e x e r t i n g a t l e a s t as much i n f l u e n c e on boat speed as the equipment. A f t e r d e v e l o p i n g the model a t l e n g t h , Pope s t a t e s , "... rowing i s an a f f a i r of men, and t h i s must be c l e a r l y u n d e r s t o o d . " McMahon (1971) s t u d i e d the e f f e c t of boat d e s i g n on the r a c i n g speeds of l i g h t w e i g h t and heavyweight crews. A t h e o r e t i c a l l i g h t w e i g h t s h e l l was m o d e l l e d t o be g e o m e t r i c a l l y s i m i l a r t o a heavyweight s h e l l , i n terms of the r a t i o s of crew weight t o t h e l e n g t h , b r e a d t h , and w e t t e d s u r f a c e a r e a of the s h e l l . I t was proposed t h a t s i m i l a r s h e l l s rowed by l i g h t w e i g h t and heavyweight crews s h o u l d f i n i s h a r a c e i n the same t i m e . Another approach t o mechanics i n rowing i s t h a t of B r e a r l e y (1977). The moment about t h e s t e r n of eight-man r a c i n g s h e l l s was c a l c u l a t e d f o r " s t a n d a r d " r i g and f o r an a l t e r n a t e r i g of the o a r s . The s t a n d a r d r i g , w i t h the sweeps s t a g g e r e d from bow t o s t e r n , w i t h bow (#1) on s t a r b o a r d and s t r o k e (#8) on the p o r t or l e f t s i d e of the s h e l l ) , was shown t o cause the boat t o waver i n i t s c o u r s e throughout each s t r o k e . T h i s w a vering i s due t o the d i f f e r e n c e between the sum of the d i s t a n c e s from the s t e r n t o the r i g g e r s on p r o t s i d e and the same sum on s t a r b o a r d . At d i f f e r e n t p a r t s of the s t r o k e , the g r e a t e r sum of d i s t a n c e s of the s t a r b o a r d r i g g e r s causes the bow of the boat t o be pushed or p u l l e d s l i g h t l y o f f c o u r s e a t t h e c a t c h and f i n i s h , r e s p e c t i v e l y . The a l t e r n a t e r i g , w i t h bow, 3, 5, and s t r o k e (#8) on the same s i d e , and 2, 4, 5, and 7 on the o p p o s i t e s i d e 59 e l i m i n a t e s the moment about the s t e r n , as t h e sums of the d i s t a n c e s from the s t e r n t o t h e r i g g e r s a r e the same f o r both s i d e s of the bo a t . I s h i k o (1971) measured the f o r c e a t the oar w i t h s t r a i n guages on the i n b o a r d p o r t i o n (between the end of the ha n d l e and the o a r l o c k ) of an o a r , and the a c c e l e r a t i o n of the s h e l l . F o r c e c u r v e s were found t o v a r y g r e a t l y from s u b j e c t t o s u b j e c t even among e l i t e members of the same crew. The a c c e l e r a t i o n s of the boat were r e l a t e d t o the f o r c e - t i m e p a t t e r n s of the o a r , but n e i t h e r f o r c e nor a c c e l e r a t i o n were a d e q u a t e l y r e l a t e d t o the k i n e m a t i c s of the s u b j e c t ' s m o t i o n s . Asami, e t a_l. ( 1978), and S c h n e i d e r , e t a l . ( 1978) r e p o r t f o r c e - t i m e c u r v e s f o r oar s or o a r l o c k s , d e t e r m i n e d w i t h s t r a i n gauges. F o r c e - t i m e c u r v e s were g e n e r a t e d i n rowing by a number of oarsmen w i t h d i f f e r e n t s k i l l l e v e l s . The f o r c e - t i m e c u r v e s were c o n s i d e r e d as p o s s i b l e i n s t r u c t i o n a l i n f o r m a t i o n t o a s s i s t i n t e a c h i n g oarsmen improved t e c h n i q u e , and t o i d e n t i f y s k i l l e d p e rformance. The c h i e f d i f f i c u l t y w i t h t h e s e d a t a i s t h a t the t e l e m e t r y equipment needed t o c o l l e c t f o r c e i n f o r m a t i o n a t the o a r l o c k or oar s h a f t i s p r o h i b i t i v e l y e x p e n s i v e . C e l e n t a n o , e t a_l. ( 1 974) s t u d i e d t h e f o r c e s i n the oar d u r i n g rowing a t s t r o k e r a t e s between about 20 and about 37 s t r o k e s per minute. The e f f e c t s of s t r o k e r a t e of the v e l o c i t y of a p a i r w i t h o u t coxwain, on s t r o k e (and d r i v e phase) d u r a t i o n , and t o t a l "work" done per s t r o k e were a l s o s t u d i e d . The s h e l l ' s f l u c t u a t i o n about i t s mean v e l o c i t y was found t o be reduced a t s t r o k e r a t e s g r e a t e r than 35 per minute. The power o u t p u t , f o r c e , and the p r o p o r t i o n of t h e s t r o k e t a k e n by the d r i v e phase 60 were found t o i n c r e a s e w i t h r a t e . M a r t i n and B e r n f i e l d (1980) s t u d i e d f i l m d a t a t o measure the v e l o c i t y of an e i g h t w i t h coxwain a t t h r e e s t r o k e r a t e s between 37 and 41 s t r o k e s per minute. The l e a s t f l u c t u a t i o n i n v e l o c i t y (a range of 2.65 m/s) o c c u r e d a t 39 s t r o k e s per minute. The g r e a t e s t mean v e l o c i t y was 6.41 m/s, and o c c u r r e d a t 41 s t r o k e s per minute. These r e s u l t s extended the f i n d i n g s of C e l e n t a n o , e t a_l. ( 1974). The c h i e f c o n t r i b u t i o n s t o the i n c r e a s e d v e l o c i t y of the s h e l l a t h i g h e r r a t e s were g r e a t e r f o r c e per s t r o k e , and the i n c r e a s e d p e r c e n t a g e of the t o t a l s t r o k e c y c l e time spent e x e r t i n g the f o r c e ( i . e., i n c r e a s e d i m p u l s e ) . S t u d i e s mentioned above as i n v e s t i g a t i o n s of the f o r c e s o c c u r r i n g i n the oar or i n the o a r l o c k (measured a t t h e p i n ) appear t o make no mention of the d i f f i c u l t y and expense i n v o l v e d i n t a k i n g t h e s e measures. In a d e s c r i p t i o n of a c o m p u t e r i z e d d a t a system f o r a f o u r - o a r e d s h e l l , K l a v o r a (1979) d e s c r i b e s s e v e r a l problems e x p e r i e n c e d by, f o r example, I s h i k o (1971), and by s e v e r a l o t h e r coaches and r e s e a r c h e r s . A system d e s c r i b e d by K l a v o r a was d e s c r i b e d as h a v i n g an " a t t r a c t i v e " p r i c e , f a r g r e a t e r than any f u n d i n g a v a i l a b l e f o r t h i s study ( i . e., the 1979 p r i c e was e s t i m a t e d a t about $10,000) A s t u d y of the p o s i t i o n of the oarsman a t the c a t c h , and the e f f e c t of t h a t p o s i t i o n of the f o r c e d e v e l o p e d i n the d r i v e phase of the s t r o k e showed l i t t l e , e xcept t h a t : u n l e s s s u b j e c t s a r e v e r y h i g h l y s k i l l e d they a r e l i k e l y t o be unable t o d u p l i c a t e a s k i l l e d motion r e l i a b l y and, the environment f o r t e s t i n g rowing motions must be made as s i m i l a r t o t h e r e a l 61 rowing motion as possible (Klavora, 1978). Very few studies have been published describing comparisons of the mechanics of rowing with ergometers and rowing in s h e l l s . Stuble, Erdman, and Stoner (1980) studied the kinematics of rowing in a boat and rowing two di f f e r e n t types of rowing ergometer. Eight subjects were filmed through several strokes in coxless pairs and in the two machines, and the kinematics of the hands and of several r e l a t i v e angles (e.g., thigh-trunk angle) were examined graphically. Stuble, et a l . were able to „ discern between members of d i f f e r e n t rowing clubs and between s k i l l l e v e l s . The movement out of the saggital plane occurring in sweep-oar rowing was ignored, and only motion in the x-y (vertical-anteroposterior) plane was examined, as in t h i s investigation. 62 BIBLIOGRAPHY Asami, T., N. A d a c h i , K. Yamamoto, K. I k u t a , and K. T a k a h a s h i . B i o m e c h a n i c a l a n a l y s i s of rowing s k i l l . i n : Asmussen, E., and K. Jjzfrgensen (eds.) Biomechanics VI-B U n i v e r s i t y Park P r e s s , pp. 109-114, (1978). Braune, W., and 0. F i s c h e r . Uber den Schwerpunkt des m e n s c h l i c h e n K o r p e r s , mit R u c k s i c h t auf d i e Avisrustung des deutschen I n f a n t e r i s t e n . Abh.d. math.-phys. c l . d . K.  Sachs. G e s e l l s c h . der W i s s ^ 26:561-672. 0 8 9 9 ) . B r e a r l e y , M. N. Oar arrangements i n rowing e i g h t s . i n : Lanady, S. P., and R. E. Machol (eds.) O p t i m a l S t r a t e g i e s i n S p o r t s ( S t u d i e s i n Management S c i e n c e and Systems; v. 5 ) , E l s e v i e r N o r t h - H o l l a n d , i n c . New York, pp 184-185, (1977). C a l d w e l l , G. E., M e c h a n i c a l Cost and Energy T r a n s f e r s as an Index of S k i l l M. Sc. T h e s i s , U n i v e r s i t y of W a t e r l o o , W a t e r l o o , O n t a r i o , (1980). Cameron, A. Some m e c h a n i c a l a s p e c t s of r o w i n g . i n : W i l l i a m s , J . G. P. and A. C S c o t t (eds.) Rowing: A S c i e n t i f i c  Approach Kaye and Ward, L t d . , London p. 64-80, (1967). Cavagna, G. A., F. P. S a i b e n e , and R. M a r g a r i a . M e c h a n i c a l work i n r u n n i n g . JL A p p l . P h y s i o l . 19:249-246, ( 1 9 6 4 ) . Cavagna, G. A., and R. M a r g a r i a , Mechanics of W a l k i n g . J .  A p p l . P h y s i o l . 21(1):271-278, (1966). Cavagna, G. A., L. Komerak, and S. M a z z o l e n i , The mechanics of s p r i n t r u n n i n g . J _ P h y s i o l . (London) 217:709-721, (1971). Cavagna, G. A., H. Thys, and A. Zamboni, The s o u r c e s of e x t e r n a l work i n l e v e l w a l k i n g and r u n n i n g . J__ P h y s i o l . (London) 262:639-657, (1976). C e l e n t a n o , F., G. C o r t i l i , P. E. d i P r a m p e r o , and P. C e r r e t e l l i . M e c h a n i c a l a s p e c t s of r o w i n g . J _ A p p l . P h y s i o l . 36(6):642-647, (1974). C h a n d l e r , R. F., C. E. C l a u s e r , J . T. M c C o n v i l l e , H. M. R e y n o l d s , and J . W. Young. I n v e s t i g a t i o n of i n e r t i a l  p r o p e r t i e s of the human body. (AD-A016 485) W r i g h t - P a t t e r s o n A i r F o r c e Base, Ohio. AMRL-TR-74-137, (1975). C l a u s e r , C. E., J . T, M c C o n v i l l e , and J . W. Young. Weight,  volume, and c e n t r e of Mass of segments of the human body. (AD 710 622) W r i g h t - P a t t e r s o n A i r Defense Base, O h i o . AMRL-TR-69-70. (1969). Dempster, W. T. Space Requirements of the Seated O p e r a t o r .  G e o m e t r i c a l , K i n e m a t i c , and M e c h a n i c a l A s p e c t s of the Body 63 With S p e c i a l R e f e r e n c e t o the Limbs. WADC T e c h n i c a l Report 55-159, W r i g h t - P a t t e r s o n A i r F o r c e Base Ohio, (1955). E l f t m a n , H. F o r c e s and energy changes i n the l e g d u r i n g w a l k i n g . Am. J . P h y s i o l . 125:339-356 (1939). Fenn, W. 0. F r i c t i o n a l and k i n e t i c f a c t o r s i n the work of s p r i n t r u n n i n g . Am. J . P h y s i o l . 92:583-611, (1930). F i s c h e r , 0. T h e o r e t i s c h e Grundlaqen f u r e i n e Mechanik der Lebenden Korper m it S p e z i e l l e n Anwendungen auf den Menschen,  sowie auf e i n i g e Bewegungs-vorqange an Maschinen. B. G. Teubner, L e i p z i g and B e r l i n . (1906). Gage, H. A c c e l e r o g r a p h i c a n a l y s i s of human g a i t . Am. Soc.  Chem. Eng. 64:137-152, (1964). G e r s t e n , J . W., W. O r r , A. W. Se x t o n , and D. Oki n E x t e r n a l work i n l e v e l w a l k i n g . A p p l . P h y s i o l . 26:186-189, (1969). Hay,. J . G. The c e n t r e of g r a v i t y of the human body. K i n e s i o l o g y I I I A. A. H. P. E. R., Washington, (1973). Hay, J . G., Moment of i n e r t i a of the human body. K i n e s i o l o g y IV A. A. H. P. E. R., Washington, (1974). I s h i k o , T. Biomechanics of row i n g . i n : V r e n d e n b r e g h t , J . , and J . W a r t e n w e i l e r (eds.) Biomechanics I I B a s e l , S w i t z e r l a n d , S. K a r g e r , AG, pp249-252, (1971). K l a v o r a , B. The e f f e c t of v a r i o u s l e g p o s i t i o n s a t the c a t c h on  the f o r c e of the rowing s t r o k e . M. Sc. T h e s i s , Lakehead U n i v e r s i t y , ( 1978T! K l a v o r a , P. Biomechanics of rowing - EDAS s t r o k e a n a l y z e r : a m i l e s t o n e i n c o a c h i n g r o w i n g . C a t c h November- December. (1979). Komi, P. V., A. I t o , B. S j o d i n , R. W a l l e n s t e i n , and J . K a r l s s o n . Muscle m e t a b o l i s m , l a c t a t e b r e a k i n g p o i n t , and b i o m e c h a n i c a l f e a t u r e s of r u n n i n g . I n t . J . S p o r t s M e d i c i n e 2(3):148-153, (1981). Krogman, W. M. and F. E. Johnson Human Mech a n i c s : Four Monographs A b r i d g e d AMRL-TDR-63-163. W r i g h t - P a t t e r s o n A i r Fo r c e Base, Ohio, (1963). M c C o n v i l l e , J . T., C. E. C l a u s e r , and J . C u z z i . A n t h r o p o m e t r i c r e l a t i o n s h i p s of body and body segment moments of i n e r t i a . (AD-A097-238) W r i g h t - P a t t e r s o n A i r F o r c e Base, Ohio. AFMRL TR-80-119. (1980). McMahon, T. P. Rowing: a s i m i l a r i t y a n a l y s i s . S c i e n c e 1.73(23) : 349-351 , ( 1 971 ). M a r t i n , T. P. and J . S. B e r n f i e l d . E f f e c t of s t r o k e r a t e on 64 v e l o c i t y of a rowing s h e l l . Med. S c i . S p o r t E x e r c i s e 12(4):250-256, (1980). Norman, R. W. , M. T. S h a r r a t t , J . C. Pe z z a c k , and E. G. Noble. . R e e x a m i n a t i o n of the m e c h a n i c a l e f f i c i e n c y of h o r i z o n t a l t r e a d m i l l r u n n i n g . i n : Komi, P. V. (ed.) I n t . S e r i e s on Bi o m e c h a n i c s , V o l . 1B Biomechanics V-B pp. 87-93, (1976). P e z z a c k , J . C , R. W. Norman, and D. A. Wi n t e r As assessment of d e r i v a t i v e d e t e r m i n i n g t e c h n i q u e s used f o r motion a n a l y s i s . J . B iomechanics 10, 377-382, (1977). Pope, D. L.., On the dynamics of men and boats and o a r s . I n : B l e u s t e i n , J . L. ( e d . ) , Mechanics and S p o r t New York, pp. 113-130, (1973). P i e r r y n o w s k i , M. R., D. A. W i n t e r , and R. W. Norman, T r a n s f e r s of m e c h a n i c a l energy w i t h i n the t o t a l body and m e c h a n i c a l e f f i c i e n c y d u r i n g t r e a d m i l l w a l k i n g . Ergonomics 2 3 ( 2 ) : 147-156, (1980). P i e r r y n o w s k i , M. R., R. W. Norman, and D. A. W i n t e r . M e c h a n i c a l energy a n a l y s e s of the human d u r i n g l o a d c a r r i a g e on a t r e a d m i l l . Ergonomics 24(1):1-14, (1981). Quanbury, A. O., D. A. W i n t e r , and G. D. Reimer. I n s t a n t a n e o u s power and power f l o w i n body segments d u r i n g w a l k i n g . J .  Human Movement S t u d i e s . 1:59-67, (1975). R o b e r t s o n , D. G. E., and D. A. Wi n t e r M e c h a n i c a l energy g e n e r a t i o n , a b s o r p t i o n and t r a n s f e r amongst segments d u r i n g w a l k i n g . J . Biomechanics 13:845-854, (1980). S c h n e i d e r , E., F. Angst, and J . D. B r a n d t . B i o m e c h a n i c s i n Rowing. i n : Asmussen, E., and K. J T r g e n s e n . Biomechanics  VI-B U n i v e r s i t y Park P r e s s , pp. 115-119. (1978). S m i t h , A. J . The k i n e t i c energy of the human body. J _ Human  Movement S t u d i e s 1(1):13-18, (1975). S t u b l e , K. R., A. G. Erdman, and L. J . S t o n e r . K i n e m a t i c a n a l y s i s of rowing and rowing s i m u l a t o r s . in_: Shoupe, T. E., and J . G. Thacker ( e d s . ) , I n t e r n a t i o n a l C o n f e r e n c e on M e d i c a l  D e v i c e s and S p o r t s Equipment. New York, ASME, pp143-151, (1980). W e l l i c o m e , J . F., Some hydrodynamic a s p e c t s of r o w i n g . i n : W i l l i a m s , J . G. P., and A. C. S c o t t Rowing: A S c i e n t i f i c  Approach Kaye and Ward L t d . London, pp.22-63, (1967). W e l l s , R. P., and G. C a l d w e l l . The e f f e c t of body markers and image s i z e on c i n e f i l m d i g i t i z a t i o n n o i s e . i n : Human  Locomation I I P r o c e e d i n g s of the Second B i a n n u a l Conference of t he Canadian S o c i e t y f o r Biomechanics (CSB) K i n g s t o n , O n t a r i o , S e p t . 1-3, pp 90-91, (1982). 65 W i l l i a m s , J . G. P., Some b i o m e c h a n i c a l a s p e c t s of r o w i n g . i n : W i l l i a m s , J . G. P. and A. C. S c o t t (eds.) Rowing: A S c i e n t i f i c Approach Kaye and Ward, L t d . , London, p. 81-109, (1967) . W i n t e r , D. A., H. G. S i d w a l l , and D. A. Hobson. Measurement and r e d u c t i o n of n o i s e i n K i n e m a t i c s . J__ B i o m e c h a n i c s . 7:157-159, (1974). W i n t e r , D. A., A. 0. Quanbury, and G. D. Reimer. A n a l y s i s of i n s t a n t a n e o u s energy of normal g a i t . B i omechanics 9:253-257, (1976). W i n t e r , D. A., A new d e f i n i t i o n of m e c h a n i c a l work done i n human movement. J . A p p l . P h y s i o l . 4 6 ( 0 : 7 9 - 8 3 , (1979a). Z s i d e g h , M. A su r v e y of the p h y s i o l o g i c a l and b i o m e c h a n i c a l i n v e s t i g a t i o n s made i n t o k a y a k i n g , c a n o e i n g and r o w i n g . Hung. Rev. S p o r t s Med. 22(2):97-115, (1981). 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            data-media="{[{embed.selectedMedia}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
https://iiif.library.ubc.ca/presentation/dsp.831.1-0077390/manifest

Comment

Related Items