Elliott, E.

Layne, C.

Schneider, C.

Zebas, C.

English

ISBS (International Society of Biomechanics in Sports): Conference Proceedings Archive

ELECTROMYOGRAPHIC RESPONSES AND FORCE APPLICATION ASSOCIATED WITH TWO LAND ROWING MODES E. H. Elliott, C. M. Schneider, C. J. Zebas University of Kansas, Lawrence, KS USA C. S. Layne Kansas State University, Manhattan, KS USA The increasing popularity of the sport of rowing and the complexity of training methods warrant research on the seasonal techniques of land and water conditioning. Research in the sportof rowing has primarily focusedon biomechanical and physiological parameters (Hagerman, 1984; Lamb, 1989). Biomechanical investigations (Martindale & Robertson, 1984) indicate that there are differences in rowing techniques between waterrowing and rowing on ergometers designed to simulate water rowing. There have been limited investigations on the neurwnuscular functions involved with ergometer rowing. The purpose of this investigation was to determine EMG activation patterns during the use of two land rowing ergometers designed to simulate water rowing. The results of this study will be used as a basis for future investigations on the comparison I of neuromuscular patterns between land and water rowing. METHODOLOGY Eleven experienced male lightweight w=70.5+ 2.8 kg) collegiate rowers from four universities were tested on two machines designed to simulate water rowing, the Concept I1 and the Gjessing ergometers. Mean height and age of the subjects were 152.2+5.7 cm and 21.7e1.3 years. During rowing, surface EMG was monitored on four muscle groups: biceps brachii, long head of the triceps, rectus femoris, and biceps femoris. EMG signals were amplified and band passed (1OHz-5Hz) prior to analogue to digital conversion at a sample rate of 1kHz. Force output was measured through a strain gauge transducer located in the draw cable on each machine. Two strain gauges and two fixed resistors were mounted on the transducer completing a full Wheatstone bridge and producing tension sensitivity twice that of a single 11-millimeter gauge. Output was processed through a differential amplifier using high gain (200) and a low pass fdter (10 Hz). AU data signals were stored on a microcomputer. Off-line signal processing produced full wave rectified, linear envelopes (20 ms time constant). Individual subject's data were averaged for each machine with respect to force onset (0.0 ms). Following a warm-up, subjects randomly began the testing procedure on either machine. Six to eight strokes were used to achieve the designated rate (30-3 1 stroked minute) and maximal power at a resistance of 29.4 N m (Wilson, Robertson, & Stothart, 1988). Six to eight sets of eight seconds of data collection were accomplishedduring the ten hard strokes on each machine. Data collection parameters included burst duration of EMG and force, time of peak activation of EMG and force, and onset time of EMG relative to force onset. Paired t-tests were used to determine the differences in these variables between the two machines. Significance was accepted at the s . 1 0  level. (a) BICW FD1OBIS t I -700.0 I 1 I I I I I I I Scale: 200.0 mcc. 1300.0 tm. mrn initiation. BICEPS FRlQRlS FORCE -tzrrrhZ BICEPS TRICEPS I I I I I I I I I I I - 7 1 . 0  Scale: 2W.Q r r rcc .  13W.Q /'--.- t ~ .  Porcrn initiation. Figure 1. Averaged EMG and force records from one subject on the ConceptII (a) and the Gjessing (b) rowing ergometers. RESULTS Figure 1 is a representative sample of one subject's data collected on the Concept I1 (a) and Gjessing (b) ergometers. This figure represents one average stroke cycle on each machine. All subjects displayed a similar EMG onset pattern across machines. The pattern of muscle activation onsets was rectus femoris, triceps, and biceps femoris. The biceps brachii were the last muscles activated. The fmt three muscles, rectus femoris, triceps, biceps femoris, were activated prior to initiation of force. Force duration on the Concept I1 was 35.7% of the stroke cycle, while on the Gjessing force duration occupied 37.9% of the swke cycle. Despite general similarities between the two machines in onset and force duration pattems, careful scrutiny of individual muscle activation patterns between machines indicate differences occurred. Table 1 Temporal Parameters of EMG Activity and Force on the Concept II and the Gjessing Rowing Ergometers Dumion Peak T i e  Onset Parameters Machine (ms) (ms) (ms> M 3 D M  S D M  SD Concept II 395 142 390 44 116 142 Biceps Brachii Gjessing 390 88 382 60 175 93 ConceptII 509*** 91 91* 78 -156 21 Triceps Gjessing 586*** 99 156* 62 -141 70 ConceptII 401 169 -100 86 -290** 179 Rectus Femoris 1 Gjessing 448 127 -48 161 -205** 234 Concept II 410 89 507** 110 271* 213 Rectus Femoris 2 Gjessing 447 111 677** 175 453* 188 Concept II 375** 115 167 105 -47 128 Biceps Femoris Gjessing 435** 93 222 100 -5 120 ConceptII 714 45 295** 34 0 0 Force Gjessing 757 103 336** 40 0 0 *QC. 10. **~<.05. ***~<.01. Table 1 shows the EMG and force parameters of the three variables: bukt duration, time of peak activation and onset time. Triceps and biceps femoris burst durations were significantly longer on the Gjessing ergometer compared to the Concept 11. Time of peak activation of the triceps and the second burst of therectus femoris were significantly greater on the Gjessing. This indicates that these variables occurred later in the EMG pattern on the Gjessing relative to force activation. The onset time of the fvst burst of the rectus femoris relative to initiation of force application was significantly lesson theGjessing compared to theconcept 11. This means that therectus femoris burst on the Gjessing occurred closer to the initiation of force. The second burst of the recw femoris during Gjessing rowing was significantly greater than the second burst of the rectus femoris observed during Concept II rowing. This means that the onset time of the second burst of the rectus femoris on the Gjessing occurred later relative to force initiation compared to the Concept II. Time of peak force was significantly greater while rowing on the Gjessing compared to rowing on theconcept 11. There were no significant differences in the biceps brachii variables. DISCUSSION While the general muscle activation orders were similar between the two land rowing machines, specific neuromuscular differences occurred. The neuromuscular differences are not surprising and support earlier biomechanical studies. Martindale & Robertson (1984) found significant differences between the movements during water sculling and the movements on the Gjessing land rowing ergometer. They suggested that arowing ergometer capable of simulating the water rowing motion would be a valuable tool for technique training. The results of the present study suggest that the design of appropriate land ergometers must also take into account neuromuscular functions involved with the skill of rowing. Lamb (1989) and Daireaux and Pottier (1983) found that the quadriceps were of primary importance during the rowing stroke. The majority of the quadriceps' involve- ment including onset and burst duration occurred in the first half of the drive phase. Likewise, this was observed in the present study, the rectus femoris and biceps femoris wereactive 60% of the total stroke time while biceps brachii wereactive45% of the total stroke time. Thus, most of the force production in the rowing stroke came from the legs extending. The biceps brachii activation onset occurred following force initiation in all subjects across both machines. This latency of the biceps brachii during land rowing is supported by Daireaux & Pottier (1983). although they did not find consistent latent biceps brachii onsetsbetween all subjects. Contrary to the present study, they found that the biceps brachii onsets and durations had substantial variability between subjects. The variability found in the Daireaux & Pottier study was probably due to the rowing experience of the subjects. They used both experienced and inexperienced rowers. Inexperienced rowers initiate the movement of the handle with their arms as opposed to experienced rowers who initiate movement of the rowing handle with the legs. In the present study, only experienced rowers were subjects, therefore, this may explain the small variabiity in the biceps brachii onsets and durations. Olbrecht & Clarys (1983) compared land training whniques versus water training for the sport of swimming. They found that the EMG puerns on dry-land machines did not mimic the ptterns observed during swimming in the water. Thus. dry- land training techniques may be questionable as to their effectiveness. In the present study, thedry-land machine that most closely mimics water rowing cannot bedetermined. Future studies on the EMG patterns during water rowing are necessary. CONCLUSION Nemmuscular pattern differences were observed which is in agreement with biomechanical research on land versus water rowing. Experienced rowers use leg muscles as the primary force during the rowing stroke which is in agreement with current rowing literatme. The arm muscles are used minimally to initiate force at the beginning of the rowing motion. As a result of this study. insight is available on the differences in EMG and force production during two modes of land rowing. Further data collection of this type is suggested during water rowing to determine the effectiveness of these machines in mimicking water rowing. REFERENCES Daireaux, A.. & Pottier. M. (1983). Etude electrornyographique (e.m.g.) de muscles representarifs du mouvement de l'aviron. Medecine du Sport, 57.21.85-27.91. Hagerman, F.C. (1984). Applied physiology of rowing. Sports Medicine, 1,303-326. Lamb. D.L. (1989). A kinematic comparison of ergometer and on-water rowing. The American Journal of Sports Medicine. 17(3): 367-373. Martindale. W.O., & Robertson. D.G.E. (1984). Mechanical energy in sculling and rowing an ergometer. C a d a n  Journal of AppliedSports Science. 9(3).153-163. Olbrecht, J., & Clarys. J.P. (1983). EMG of specificdry land training for the frontcrawl. In Hollander, Huying. de Groot (Eds.), Biomechanics and Medicine in Swimming ( pp. 136-141). Champaign. IL: Human Kinetics. Wilson, J.-MJ., Robertson. D.GE., & Stothart, JP. (1988). Analysis of lower limb muscle function in ergometer rowing. International Journal of Sport Biome- chanics, 4.315-325. 

ELECTROMYOGRAPHIC RESPONSES AND FORCE APPLICATION ASSOCIATED WITH TWO LAND

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ELECTROMYOGRAPHIC RESPONSES AND FORCE APPLICATION ASSOCIATED WITH TWO LAND

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