Isokinetic trunk dynamometry in diferent swimming strokes

Abstract

Objective: To compare the effect of asymmetric and symmetric swimming strokes on muscle activity of the trunk flexor and extensor muscles. Methods: Fourteen elite speed swimmers, specialists in one of four swimming styles, all without any history of spinal cord injury, were divided in two groups: 1) asymmetric group, consisting of five athletes specializing in the freestyle stroke and three in the backstroke; and 2) symmetric group, consisting of four athletes specializing in the butterfly stroke and three in the breaststroke. All the swimmers were assessed using a Cybex 6000 isokinetic dynamometer. Results: The acceleration time for the trunk flexor group at a speed of 120° per second was greater in the symmetric group (p=0.054). The power of the extensor group at speeds of 90° and 120° per second was greater in the asymmetric than in symmetric group (p=0.053 and 0.052), respectively. There was no significant statistical difference for any of the other variables assessed. Conclusion: The asymmetric strokes (crawl and backstroke) provided a more efficient muscular response (recruitment) in the trunk flexor muscles, which may be due to the constant maintenance of isometric contraction of the abdominal muscles.