DRAG FORCE IS THE MAIN PROPULSIVE FORCE OF THE HAND IN CRAWL STROKE
Gourgoulis, V., Boli, A., Aggeloussis, N., Toubekis, A. G., Vezos, N., Kasimatis, P., & Mavrommatis, G. (2010). Relative contribution of drag and lift forces in the separate phases of the front crawl swimming. A paper presented at the XIth International Symposium for Biomechanics and Medicine in Swimming, Oslo, June 16–19, 2010.
This study evaluated the relative contribution of drag and lift force in three separate phases of the underwater stroke in front crawl swimming. Female swimmers (N = 10) swam 25 m front crawl with maximal intensity, with pull-buoy and without breathing in the middle of the pool. The underwater stroke was divided in three phases: a) entry and catch, b) pull, and c) push. The hydrodynamic coefficients and the propulsive forces of the hand were calculated/estimated.
During the pull phase, the mean drag force was significantly greater than lift force. During the push phase, no significant difference was found between drag and lift force. The drag force was not significantly different between the pull and push phases, while the lift force was significantly higher during the push vs. the pull phase.
Implication. Drag force is decisive for propulsion in both propulsive phases of the underwater motion of the hand, while the contribution of lift force increased during the push phase. [There is the possibility that the use of the pull-buoy distorted the findings to what might have been observed in free-swimming, particularly since only the hand was evaluated as part of the propulsive surface of the arm.]
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