Elipot, M., Houel, N., Hellard, P., & Dietrich, G. (2010). Motor coordination during the underwater undulatory swimming phase of the start for high level swimmers. A paper presented at the XIth International Symposium for Biomechanics and Medicine in Swimming, Oslo, June 16–19, 2010.

This study determined the motor coordination that high level male swimmers (N = 12) were able to produce during the underwater undulatory swimming phase of the start. Ss were asked to perform the most efficient grab start. Swimmers were filmed during the whole underwater phase. Nine anatomical landmarks were identified on the swimmer’s body. To minimize the error during the digitizing process, both sides of the swimmers were assumed to be symmetric. Ankle, knee and hip angles and positions were calculated. Motor coordinations and synergies were identified by computing cross-correlation functions.

There were significant cross correlations between: the hip angle and the ankle angle, the hip angle and the trunk angle, the hip angle and the thigh angle of attack, the knee angle and the thigh angle of attack, the knee depth and the thigh angle of attack, the knee depth and the hip angle, the knee depth and the knee angle, the hip angle and the leg angle attack, the knee angle and the leg angle attack, the ankle depth and the hip angle, the ankle depth and the knee angle, the toes depth and the hip angle, the toes depth and the knee angle, the toes depth and ankle angle.

Implication. During the underwater undulatory swimming, swimmers have to find the optimal leg amplitude. It seems that high level swimmers control leg amplitude through a strong joint synergy between the hip action and the ankle action. Knee action is also important but seems to have an independent effect on leg amplitude.

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