INTRODUCTION Swimming parachutes are widely used as a practical and low-cost tool for resisted swimming and its shape, cross-sectional area, as well as its speed, might influence the magnitude of the added load (Cortesi et al., 2019). Although its effects on stroke kinematics and coordination have been discussed in the literature, information on the training loads imposed by swimming parachutes are limited (Schnitzler et al., 2011) and usually not provided by the manufacturer. The aim of this study was to quantify the external loads imposed by a commercially available set of swimming parachutes, by establishing the hydrodynamic characteristics of parachutes of three different sizes. METHODS Three sizes of swimming parachutes were tested (NABAIJI 900): small (20 cm2), medium (23 cm2) and large (28 cm2). The protocol consisted of 30 passive Drag trials (10 for each parachute size) towing the parachutes for 25 m at constant speeds (0.6-2.4 mEs-1), using an electromechanical device (1080 Sprint, Sweden; 333 Hz). The average values from 10~20 m were considered. A power regression between Drag and speed was established for each parachute, as follows: D = k x v^(n+1); in which D is the Drag force, k is the constant of proportionality of the equation (i.e., the Drag factor), and v is the towing speed. The coefficient of determination (R2) was used to indicate the goodness of fit of the Drag vs. speed regressions, for each parachute size. RESULTS The small size parachute presented a Drag factor of 10.0 kg m-1 (R2=0.99), while the values for medium and large sizes were 12.9 kg m-1 (R2=1) and 23.3 kg m-1 (R2=1), respectively. DISCUSSION The external loads imposed by a parachute depend on the swimming speed and/or the parachute size. The medium parachute increased the Drag factor by 28%, compared to the small size, while the large parachute increased it 81%, compared to the medium size. Swimming industry should consider producing mre intermediary sizes of parachutes, to allow a more precise manipulation of training load in resisted swimming.
© Copyright 2023 XIVth International Symposium on Biomechanics and Medicine in Swimming Proceedings. Published by evoletics Media. All rights reserved.