A 30-Min Rest Protocol Does Not Affect W′, Critical Power, and Systemic Response

Purpose This study aimed to assess and compare the systemic response of oxygen uptake kinetics and muscle deoxygenation between a 30-min rest protocol and a multivisit protocol on the parameters of the power-duration relationship (i.e., critical power [CP] and W '). Methods Nine endurance-trained triathletes reported to the laboratory on five occasions: a preliminary graded exercise test and a familiarization, a 30-min single-visit protocol (time trials of 10, 5, and 2 min in that order interspersed with 30 min rest), and a multivisit protocol (time trials of 10, 5, and 2 min in randomized order interspersed by >24 h rest). Heart rate (HR) was recorded continuously, respiratory gases were measured breath by breath, and deoxygenation was recorded at 10 Hz using near-infrared spectroscopy (NIRS) during all tests. Blood lactate (BLa-) concentration was measured before all time trials. Maximal HR (HRmax), oxygen uptake (VO2) during the first 2 min (VO2onset), mean response time, end-exercise VO2 (VO2peak), VO2 amplitude (amplVO(2)), O-2 deficit, NIRS tau, amplitude (amplNIRS), and time delay were assessed. To compare the two protocols and to assess the differences in W ' and CP, a paired sample t-test was used as well as a two-way ANOVA to assess the differences between trials and/or protocols, including trial-protocol interactions. Results No significant differences, and trivial effect sizes, were found for W ' and CP between protocols (P = 0.106-0.114, d < 0.01-0.08). Furthermore, no significant differences between protocols were found for all parameters, except for [BLa-]. Significant differences between trials were found for VO2ampl, VO2onset, NIRS tau, amplNIRS, [BLa-], and HRmax. Conclusion Results suggest that W ' and CP can be determined using the 30-min rest protocol without confounding effects of previous severe exercise compared with the multivisit protocol.

Automated summary

The study found no significant difference in assessing the parameters of the power-duration relationship between the 30-min rest protocol and the multivisit protocol. Except for VO2 amplitude, VO2 onset, NIRS tau, NIRS amplitude, blood lactate concentration, and maximal heart rate, there were no significant differences in other parameters between the two protocols.