Purpose: It has been suggested that the optimal stroke rate in rowing is partly determined by the stroke-rate dependence of internal power losses. This should be reflected in a stroke-rate dependency of gross efficiency (egross). The purpose of this study was to investigate if egross is affected by stroke rate. A second aim was to determine whether internal power losses can be estimated by the negative power output during the stroke cycle (Pnegative). Methods: Seventeen well-trained female rowers participated in this study. They rowed three trials on a modified rowing ergometer on slides at a submaximal intensity, with a respiratory exchange ratio of 1 or close to 1. Stroke rates were 28, 34, and 40 strokes per minute. The trials were fully randomized. Power transfer to the flywheel was kept constant whereas egross was determined during each trial. Results: No significant differences in egross were found between conditions. This finding suggests that in rowing internal power losses are not influenced by stroke rate. Furthermore, although Pnegative increased at increasing stroke rate (P < 0.001), no relationship was found with egross. This suggests that Pnegative is not a reliable measure to estimate internal power losses. Conclusion: This study shows that within the range of stroke rates applied in competitive rowing, internal power losses are unrelated to rowing cycle frequency.
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