Purpose: This study aimed to investigate the influence of prior heavy- and severe-intensity exercise on the oxygen uptake (VO2) kinetics and the power-duration relationship. Methods: Ten cyclists performed 13 exercise tests during a 4-wk period, consisting of a ramp test to determine the gas exchange threshold (GET) and the peak VO2, followed by a series of square-wave tests to exhaustion under three conditions: no prior exercise (control), prior heavy exercise (6 min at a work rate above GET but below critical power [CP)], and prior severe exercise (6 min at a work rate above the CP). Pulmonary gas exchange was measured throughout the exhaustive exercise bouts and the parameters of the power-duration relationship (CP and the curvature constant, W') were determined from the linear work-time model. Results: Prior heavy exercise increased the amplitude of the primary VO2 response (by ~0.19 ± 0.28 L/min, P = 0.001), reduced the VO2 slow component trajectory (by 0.04 ± 0.09 L·min-2, P = 0.002), and increased the time to exhaustion (by ~52 ± 92 s, P = 0.005). The CP was unchanged (control vs prior heavy: 284 ± 47 vs 283 ± 44 W; 95% confidence interval, -7 to 5 W), whereas the W' was increased by heavy-intensity priming (16.0 ± 4.8 vs 18.7 ± 4.8 kJ; 95% confidence interval, 0.3-5.2 kJ). Severe-intensity exercise had a similar effect on the VO2 kinetics but had no effect on the time to exhaustion, the CP (275 ± 45 W), or the W' (16.7 ± 4.7 kJ). Conclusions: Prior heavy-intensity exercise primes the VO2 kinetics and increases the amount of work that can be performed above the CP.
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