Development and Validity Assessment of the Max Power Model for the Detection, Separation, and Quantification of Differences in Resistive and Propulsive Forces in Swimming

Abstract

Thesis (PhD) - Indiana University, School of Health, Physical Education and Recreation, 2006Purpose: The purpose of this study was twofold. First, a new method, the Max Power Model, for assessing resistive (Fres) and propulsive (Fprop) forces using tethered swimming was developed. The Max Power Model (MPM) is based on the maximum power that a swimmer can deliver to an external load while swimming (Pmax) and its relationship with the maximum velocity of the swimmer (vmax). The development of the MPM was accomplished in three ways: examination of the shape of the Pmax vs. vmax curve, development of a method of comparing Pmax vs. vmax curves, and finally testing the sensitivity of the method to large changes using the four competitive strokes and underwater dolphin kicking. Second, the validity of the MPM was assessed by comparison with the Velocity Perturbation Model (VPM) and response to independent changes in Fres and Fprop during swimming (as supplied by a pocketed dragsuit, a wetsuit, hand paddles, fist gloves). Results: The MPM was developed effectively. The Pmax vs. vmax curve was found to be best described as an exponential function. Comparisons of Pmax vs. vmax curves were therefore made after linearization using the natural log of Pmax. If the slopes were similar, the comparisons were accomplished using ANCOVA with vmax as the covariate, otherwise a t-test for differences in slope was used. The MPM was sensitive to large changes in the swimming condition as seen through significant differences (p < 60; 0.05) in an ANCOVA for competitive stroke and a significantly different slope of ln(Pmax) vs. vmax for underwater dolphin kick in comparison with the competitive strokes. Assessment of the validity of the MPM yielded mixed results. The MPM showed a strong relationship to the VPM. However, the VPM showed no significant differences between any of the equipment treatment conditions in either the calculated Fres or the drag coefficient indicating an inability to detect small changes in Fres and Fprop. The MPM showed more promise, responding as expected to a majority of the equipment conditions. Conclusion: While still in need of further exploration and validation, the MPM has promise as a simple method to detect, separate, and quantify differences in Fres and Fprop during swimming