The purpose of this study was to describe the VO2 kinetics above and below respiratory compensation point (RCP) during swimming. After determination of the gas-exchange threshold (GET), RCP and VO2max, 9 well-trained swimmers (21.0±7.1 year, VO2max=57.9±5.1 ml.kg - 1.min - 1), completed a series of "square-wave" swimming transitions to a speed corresponding to 2.5% below (S - 2.5%) and 2.5% above (S+2.5%) the speed observed at RCP for the determination of pulmonary VO2 kinetics. The trial below (~2.7%) and above RCP (~2%) was performed at 1.28±0.05 m.s - 1 (76.5±6.3% VO2max) and 1.34 0.05 m.s - 1 (91.3±4.0% VO2max), respectively. The time constant of the primary component was not different between the trials below (17.8±5.9 s) and above RCP (16.5±5.1 s). The amplitude of the VO2 slow component was similar between the exercise intensities performed around RCP (S - 2.5%=329.2±152.6 ml.min - 1 vs. S+2.5%=313.7±285.2 ml.min - 1), but VO2max was attained only during trial performed above RCP (S-2.5%=91.4±5.9% VO2max vs. S+2.5%=103.0±8.2% VO2max). Thus, similar to the critical power during cycling exercise, the RCP appears to represent a physiological boundary that dictates whether VO2 kinetics is characteristic of heavy- or severe-intensity exercise during swimming.
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