Sequencing of actions affects force production for ergometer rowing
Coghlan, Kieran Anthony
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An aspect of rowing technique that enjoys near consensus among coaches is that the elbows must be fully extended during the majority of the power phase of the stroke. A limitation of power transfer to the oar is often the reason given as to why flexed elbows during the initial phases of the stroke are undesirable. There is no real biomechanical basis for this reasoning. The purpose of this project was to investigate the differences in force profiles between straight- and bent-elbow catch techniques for ergometer rowing. Six experienced, male college rowers were recruited and performed two different catch techniques on an instrumented rowing ergometer: one with elbows straight throughout the catch and early drive phase, and one in which the elbows flexed throughout the drive. Data collected included force data from a transducer-equipped rowing machine, elbow and knee 3-D joint angles, and EMG for muscle timing. Four dependent measures were calculated from the data: average work per stroke, percent of work done in the first &frac13; of the drive, average peak force per stroke, and average time to 1⁄2 peak force per stroke. No significant differences in work per stroke (p = 0.61) nor peak force per stroke (p = 0.06) between conditions were found. The bent arm style yielded an average 563 Joules, and 1085N, and the straight arm style averaged 570 Joules and 1140N. Percent work done in the first 1/3 of the drive was significantly larger for the bent arm style, at 23.1% vs. 19.3% (p < 0.01). Time to 1⁄2 peak force was significantly lower for bent arms at 9.0% of stroke cycle, vs. 10.3% for the straight arm condition (p < 0.01). Hydrodynamic principles indicate that for a given amount of work per stroke, a force profile that biases the work toward the early portion of the drive is beneficial. The results of this study suggest a rowing style where elbow flexion initiates the drive (power) phase of the stroke earlier, may have advantages over the straight arm style.