Paddle propulsive force and power balance: a new approach to performance assessment in flatwater kayaking.

This study aims to determine the propulsive force (F p ) and its timing of application during the paddle stroke confirming the dynamic balance between propulsive and drag powers (P p = P d ) in kayaking performance. Ten male sub-elite paddlers participated in the study. The athletes carried out three trials of 50 m at three different velocity ranges: 2.70 - 3.00 m/ s; 3.01 - 3.50 m/s and 3.51 - 4.00 m/ s. A constant velocity during each trial was maintained and the section between 15 and 40 m of the total pool length was considered for further analysis. Data were collected using the E-kayak system provided of an instrumented paddle and 2D video analysis. It was observed that the propulsive force increases in intensity (up to 90% of the peak force) as the velocity increases. The dynamic balance between P d and P p was confirmed with a Bland and Altman plot (estimated bias: 0.2; LoA: 12.8 and 13.3 W). The related comparisons between the power parameters showed no significant difference ( p > 0.050) in each of the considered velocity. By applying the dynamic balance theory between P p = P d on the data obtained from the interaction among GPS, force on the paddle and 2D video analysis, it is possible to acquire essential information (F p , P p ) to monitor the flatwater kayaking performance.