Technique is important in rowing. The athlete has to minimize energy loss and maximize power output (Prower). For steady state rowing the power equation is: Prower = Pmetabolic·egross = -(Pdrag+PDv+Pblade) [2], with Pmetabolic the metabolic power production and egross the gross efficiency. Pdrag and PDv describe power loss to shell drag. Pdrag is the power loss that occurs if shell velocity would be constant. PDv is the additional power loss resulting from velocity fluctuations. Pblade describes power loss at the blades during push off. We investigated how the execution of the stroke is related to velocity efficiency (evelocity = 1 - PDv/Prower [1]). The study was performed using a rowing ergometer. The ergometer was put on wheels, to allow it to move back and forth. It was coupled to a motor that dissipated power in a velocity-dependent way, similar to PDv in on-water rowing. The first aim of this study was to determine if the better performing athletes in a group of well-trained rowers have a higher evelocity in addition to the expected higher ÿV O2max. The second aim was to investigate which kinetic technique variables are related to differences in evelocity. METHODS 22 Well-trained female rowers participated. All performed a 2000m time trial on the modified ergometer. Forces on the handle and foot stretcher (Fhandle and Fstretcher) were recorded and ÿV O2max was determined; egross was determined separately. Timing of Fhandle and Fstretcher was described by rower induced impulse fluctuations (RIIF) of the ergometer, which were determined by calculating the time integral of the net force on the ergometer (i.e., Fhandle+Fstretcher) for discrete parts of the rowing cycle. A stepwise regression analysis was performed using ÿV O2max, evelocity and egross to predict 2000m time. Correlations were established between evelocity and RIIF values. RESULTS AND DISCUSSION Total explained variance for 2000m time was 78%; 14% was explained by evelocity (P<.05). Significant negative correlations were found between evelocity and RIIF for the complete cycle, for the phases just before and after the catch and for the recovery phase (P<.01), meaning that low RIIF will lead to high evelocity. When Fhandle = -Fstretcher, ergometer acceleration will be zero; RIIF will be zero and evelocity will be 1. Yet, the associated movement pattern is unlikely to allow optimal use of large muscle groups and Prower would be low. The best technique will be a compromise between maximum Prower and maximum evelocity. The timing of forces around the catch is important. High Fstretcher not accompanied by similar Fhandle should be avoided as it will lead to high RIIF. The rower`s C.O.M. velocity during the recovery phase should be kept to a minimum. After the catch the connection from hips to hands to should be stiff to ensure an optimal transfer of Fstretcher to the handle.
© Copyright 2007 12th Annual Congress of the European College of Sport Science, Jyväskylä, Finland - July 11-14th 2007. All rights reserved.