The Effect of Breathing on Hip Roll Asymmetry in Competitive Front Crawl Swimming
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Abstract
Front crawl swimming is a cyclic activity in which swimmers alternate arm and leg movements to create propulsive forces while the body rotates about its longitudinal axis. It has been suggested that breathing increases body rotation and potentially disrupts the symmetry of the stroke. This study quantified the effect of breathing on hip roll angle using a body-fixed (lower back) tri-axial accelerometer. Twenty (13 male, 7 female) provincial and national level swimmers performed four 100m front crawl trials at 70% of their best 100m time with 2 minutes recovery between trials. Four breathing conditions were tested: 1) unilateral preferred side, 2) unilateral non-preferred side, 3) bilateral and 4) non-breathing (snorkel). Peak unilateral hip roll angles, total hip roll angle and a hip roll asymmetry index were calculated for each condition. The results showed that total hip roll angle was significantly greater (p < 0.05) in the preferred (114.8o), non-preferred (118.8o) and bilateral (117.2o) breathing conditions compared to the non-breathing condition (108.3o). Further, subjects rolled significantly more (p < 0.05) to the preferred side than the non-preferred side when not breathing in the unilateral conditions (54.3° vs. 51.7°) and significantly more (p < 0.05) to the non-preferred side in the non-breathing condition (56.2o vs. 52.1o). Finally, the unilateral breathing conditions demonstrated significantly greater hip roll asymmetry than the non-breathing and bilateral conditions, whilst the bilateral breathing condition demonstrated significantly less hip roll asymmetry than the non-breathing condition. The findings demonstrate that breathing patterns affect hip roll asymmetry when performing front crawl at a submaximal speed. The results also support the use of an accelerometer to measure hip roll angles in front crawl swimming.