The interplay between arms-only propelling efficiency, power output and speed in master swimmers

To explore the interplay between arms-only propelling efficiency (η p), mechanical power output ( $$\dot W_{\text{tot}}$$ ) and swimming speed (V); these three parameters are indeed related through the following equation V 3 = 1/kη p $$\dot W_{\text{tot}}$$ (where k is the speed-specific drag; k = F/V 2); thus, the larger are η p and $$\dot W_{\text{tot}}$$ the larger is V. We furthermore wanted to test the hypothesis that a multiple linear regression between $$\dot W_{\text{tot}}$$ , η p and V would have a stronger correlation coefficient than a linear regression between $$\dot W_{\text{tot}}$$ and V alone. To this aim we recruited 29 master swimmers (21 M/8F) who were asked to perform (1) an incremental protocol at the arm-ergometer (dry-land test) to determine $$\dot W_{\text{tot}}$$ at $$\dot V$$ O2max (e.g. $$\dot V$$ max); (2) a maximal 200 m swim trial (with a pull buoy: arms only) during which V and η p were determined. No relationship was found between $$\dot W_{\text{max}}$$ and η p (not necessarily the swimmers with the largest $$\dot W_{\text{max}}$$ are those with the largest η p and vice versa) whereas significant correlations were found between $$\dot W_{\text{max}}$$ and V (R = 0.419, P = 0.024) and η p and V (R = 0.741, P = 0.001); a multiple linear regression indicates that about 75 % of the variability of V can be explained by the variability of $$\dot W_{\text{max}}$$ and η p (R = 0.865, P