Wakayoshi, K., Shiraki, T, Ogita, F, & Kitajima, M. (2010). Determination and validity of critical velocity in front crawl, arm stroke and leg kick as an index of endurance performance in competitive swimmers. A paper presented at the XIth International Symposium for Biomechanics and Medicine in Swimming, Oslo, June 1619, 2010.

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Critical swimming velocity (Vcri) is defined as the swimming velocity which could be theoretically maintained forever without exhaustion. It could serve as an index of endurance swimming performance. This study determined the critical velocity for whole crawl stroke, arms-only, and legs-only performance. Whether the critical velocities of each corresponded to the maximum lactate steady-state was determined. Male college swimmers (N = 14) were tested in a flume. Varied flow velocities were presented to determine critical velocity for all treatments. Exhaustion was defined by the S not being able to maintain the water flow velocity (i.e., moving 1 m back from the initial position). For the maximum lactate steady-state test, Ss performed swimming, pulling, and kicking for 20 minutes (5 minutes x 4 stages) at the velocity corresponding to Vcri-s, Vcri-p and Vcri-k. The 20-minute swim was interrupted by three short rest periods (<60s) for blood sampling. Blood lactate concentration was determined before, during the three rest periods, immediately after, and 3 and 5 minutes after each trial.

The relationships between distance and time in swimming, pulling, and kicking were very high in all Ss. In the maximum lactate steady-state test, Ss maintained the critical velocity for 20 minutes in all conditions. No significant differences were found in blood lactate measured after four stages between the three conditions.

Implication. Critical velocity can be determined by the relationship between distance and time for swimming, pulling, and kicking. The critical velocity is a good estimate of the maximum lactate steady-state for each activity.

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