de Jesus, Kelly, de Jesus, Karla, Figueiredo, P., Alves, P. G., Vilar, S., Vilas-Boas, J. P., & Fernandes, R. J. (2011). Identifying fatigue effects in butterfly kicking during a maximal 100 m event. Medicine and Science in Sports and Exercise, 43(5). Supplement abstract 1776.

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This study described and compared the multi-joint sequence of the first and second downbeat actions in the first and fourth laps of a maximal 100 m butterfly swimming trial in three females. Two cameras, one above and one below water, positioned in the sagittal plane, were used for movement analysis. The butterfly kick was divided into the first downward phase, the first upward phase, the second downward phase, and the second upward phase. The phase durations were normalized for one stroke cycle. Kinematical analysis was conducted at the first and fourth laps of the 100 m trial.

The kick is a proximal-distal joint sequence (hip-knee-ankle) at the first and second downbeats for both laps. The knee joint angular displacement at the first downbeat action was higher (the knee moved through a bigger arc) for the fourth than the first lap. For the second downbeat, the timing of ankle joint extension was observed to be later in the fourth lap than that obtained for the first one. As a swimmer progresses in a butterfly race, in the early stages the knee action is smaller than in the fatigue stages. The sequence of the kicking action slows in fatigue with the ankle taking longer to activate than compared to the first phase of a race. This suggests that a conscious effort to kick small and fast in the latter stages of a butterfly race could be beneficial.

Implication. Fatigue in a butterfly race does not change the joint segment sequences of the kicking action. As fatigue occurs, the knee action is exaggerated and the ankle action is delayed when compared to non-fatigued kicking. Performance is likely to be improved if this skill deterioration is at least delayed by concentrating on kicking small and fast.

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