In swimming, stroke is composed of different phases: entry-catch, pull, push and recovery. Arm coordination is important and related with freestyle performance. Index of Coordination (IdC) allows precise quantification of lag time between start of propulsion by one arm and end of propulsion by the other. Recent studies have emphasized the close relationship between arm coordination and velocity, but only one has included resistance (Telles et al., 2011). Therefore, the aim of this study was to analyze the relationship between IdC and technical parameters, using semi-resisted swimming with different loads. Methods: The test consisted on eleven 12.5m trials on semitethered swimming. Eighteen swimmers pulled a different load each trial, from 1.59 to 7.84kg. Swimmer`s feet were tied together, keeping a pull-buoy between legs and isolating the upper limb action. No breathing was allowed. The test was recorded from a frontal and two lateral underwater cameras (50 Hz). IdC was assessed for each trial. Pearson`s correlation coefficients were calculated between IdC and mean speed (v), stroke rate (SR), stroke length (SL) and stroke index (SI) (level of significance: p<0.05). Results: Coordination mode used in free and semi-tethered swimming was superposition (IdC>0%). IdC was 6.6% when swimming free and it increased significantly with loads (p<0.05). It was, on average, 7.1% with 1.59kg and 14.8% with 7.84kg. Significant correlations (p<0.01) were found between IdC and load (r=0.91), v (r=-0.94), SL (r=-0.93) and SI (r=-0.95), but not between IdC and SR. Discussion: Concerning arm coordination in swimming, IdC was higher when swimming with parachute (0.1%) than when swimming free (-2.3%) (Telles et al., 2011). Catch-up model was used for long and middle distance (3000 to 200m), while for sprints (100 and 50m) opposition or superposition were used (Chollet et al., 2000; Seifert et al., 2004). In the latter case, the relative duration of non-propulsive phases decreased, while the duration of propulsive phases increased. The same happened in semi-tethered swimming, where swimmers used superposition. IdC increased, v, SL and SI decreased and SR remained constant as loads increased. Some of these results are not in keeping with previous studies which, however, did not include loads (Alberty et al., 2005; Chollet et al., 2000). These differences may be due to the application of loads, which led to fatigue and, therefore, higher IdC (Alberty et al., 2005). Considering that resisted swimming is a widely applied training method, results suggest that load should be carefully controlled, as it modifies swimming coordination.
© Copyright 2012 17th Annual Congress of the European College of Sport Science (ECSS), Bruges, 4. -7. July 2012. Published by Vrije Universiteit Brussel. All rights reserved.