Introduction: The hydrodynamic resistance experienced during swimming is called active drag. A number of methods for measuring active drag have been proposed but there is no gold standard, with the most current methods still producing conflicting data (Toussaint et al., 2004). To date, all active drag studies have been on able-bodied swimmers; no study has yet examined the active drag of Paraswimmers. The two aims of this study are to: 1) determine the active drag of elite Para-swimmers, and 2) compare two current methods of measuring active drag . the Assisted Towing Method (ATM) and the Naval Architecture Based Approach (NABA). Methods: Maximum swimming speed (v.oo) of five female and three male elite Para-swimmers (IPC classes S5-S14) was determined. Participants were then towed, using a motorised drum, while holding a fixed `passive` position with their arms at their sides. Passive drag was recorded at v.oo (Fp.oo) and 10% faster speed, v..o (Fp..o), using a load cell incorporated into the towing cable. Finally, the cable force (Ft) was recorded as participants swam maximal effort freestyle while being towed at v..o. All trials were repeated three times to assess the repeatability of the methods. Active drag (F) at each participants v.oo was calculated as follows: Assisted Towing Method (ATM): F =(Ft . v..o . v.oo2) / (v..o3 - v.oo3) Naval Architecture Based Approach (NABA): F = Fp.oo + Ft - (Fp..o - Fp.oo). Results: Swimmers v1oo ranged from 1.27-1.74 m/s. F range was 54.7-252.2 N (ATM) and 72.2- 129.5 N (NABA).When normalised for speed (F/v.oo2), the active drag range was 20.4- 58.3 kg/m (ATM) and 28.7-45.0 kg/m (NABA). No association was found between IPC Class and speed normalised active drag. NABA produced more repeatable ([(Fmax - Fmin)/Fmean] × 100) active drag values over the 3 trials (NABA: 0.1-11.9%; ATM: 11.9-50.4%). Discussion: Previous research has shown a significant correlation between passive drag and IPC Class (Oh et al., 2013). The current study found no relationship between active drag and IPC class. Active drag will be greatly influenced by the technique used by the swimmer. This does not apply to passive drag. NABA and ATM both require measurement of v.oo. Measurement errors in v.oo will be propagated to a much greater extent in the ATM method, than in the NABA, as the former method incorporates the square and the cube of v.oo in the active drag calculation.
© Copyright 2014 19th Annual Congress of the European College of Sport Science (ECSS), Amsterdam, 2. - 5. July 2014. Published by VU University Amsterdam. All rights reserved.