Gourgoulis, V., Aggeloussis, N., Mavridis, G., Boli, A., Toubekis, A. G., Kasimatis, P., Vezos, N., & Mavrommatis, G. (2010). The acute effect of front crawl sprint-resisted swimming on the direction of the resultant force of the hand. A paper presented at the XIth International Symposium for Biomechanics and Medicine in Swimming, Oslo, June 16–19, 2010.

"For effective propulsion the resultant force produced by a swimmer’s hand should be aimed as much as possible in the swimming direction (Toussaint et al., 2000). Moreover, it is suggested that in-water resistance training methods, such as sprint-resisted swimming, would be more effective for the improvement of the swimming performance."

This study assessed the influence of sprint-resisted swimming on the resultant forces produced by the hand. Female swimmers (N = 5) swam 25 m front crawl with maximal intensity, without and with added resistance. A bowl with a capacity of six liters was used as added resistance. The underwater motion of the right hand was recorded using four cameras and selected points were digitized using the Ariel Performance Analysis System. Sanders' hydrodynamic coefficients and methodology were used to estimate the drag, lift, and resultant force of the swimmers' hands. The angles between the resultant forces and the axes of propulsion were calculated.

During resisted swimming, the magnitude of the drag, lift, and the resultant and effective propulsive forces were not altered significantly. However, the angle between the vector of the resultant force and the axis of swimming propulsion in the pull phase was decreased significantly during resisted swimming when compared to free swimming.

Implication. During sprint-resisted swimming, the angle formed between the resultant force vector and the axis of the swimming propulsion was decreased significantly in the pull phase and thus the resultant force was steered more in the forward swimming direction. Consequently, it could be speculated that front crawl sprint-resisted swimming might contribute to the learning of a more effective application of the propulsive forces. [However, the direction of force application is not the only factor involved in crawl stroke propulsion. Maglischo and Maglishco showed that resisted swimming shortened stroke length, which could easily offset any benefit a change in force direction might offer.] Whether or not the change in force direction offered by resisted swimming does beneficially influence free swimming needs to be assessed.

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