Pringle, J., Hunt, J., Dekerle, J., & Brickly, G. (2009). Critical speed, anaerobic distance capacity and swimming performance after prior heavy and severe exercise. ACSM 56th Annual Meeting, Seattle, Washington. Presentation Number 555.

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"Prior heavy intensity exercise enhances exercise tolerance due to a reduced oxygen uptake slow component in subsequent exercise, most likely consequent to an improved muscle hyperaemia. However, prior severe intensity work may reduce exercise tolerance by depleting the anaerobic work capacity (AWC)."

This study tested the hypothesis that prior heavy intensity exercise improves performance whilst severe exercise decreases performance in proportion to the (known) prior depletion of anaerobic work capacity. Swimmers (N = 9) completed three time-trial maximal efforts (100, 400, and 800 m; under control conditions), from which critical swimming speed (slope of regression between distance and time) and anaerobic distance (work) capacity were derived. Separately, swimmers repeated the 100 m and 800 m race simulations immediately preceded by either heavy (198 seconds at 95% critical swimming speed) or severe intensity exercise (180 seconds at 105% critical swimming speed), the latter designed to deplete ~50% anaerobic distance capacity. The critical swimming speed and anaerobic distance capacity were recalculated under these prior-exercise conditions.

Prior heavy intensity exercise did not improve performance in either the 100 m or the 800 m race–simulation performances. Prior severe exercise worsened performance in the 100 m race, but not in the 800 m race. In the control condition the critical swimming speed was ~1.17 m/s and did not change after either heavy or severe prior exercise. Anaerobic distance capacity was similar in the control and after heavy exercise conditions, but was reduced by ~40% after severe exercise. The percentage increase in 100 m race time (i.e. worsening) after severe prior exercise was significantly related to the reduction in anaerobic distance capacity incurred (r = 0.72).

Implication. Critical swimming speed appears to define the upper limit at which anaerobic work capacity can be preserved in prior (warm-up) exercise. The observed decrement in short-duration performance was partly influenced by the depletion anaerobic distance (work) capacity incurred during prior severe exercise.

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