Physiological and perceived exertion responses at intermittent critical power and intermittent maximal lactate steady state.

The aim of this study was to compare the power outputs of the intermittent critical power (CPi) with the intermittent maximal lactate steady state (MLSSi) and to compare the physiological and perceptual responses exercising at CPi and MLSSi. Ten subjects performed intermittent trials on a cycle ergometer to determine CPi and MLSSi using 30:30 seconds of effort and pause. The oxygen uptake (&OV0312;o2), heart rate (HR), blood lactate concentration ([Lac]), and rating of perceived exertion (RPE) responses were compared during 30-minute cycling at CPi and MLSSi. The CPi (267 ± 45 W) was similar to MLSSi (254 ± 39 W), and they were correlated (r = 0.88; p < 0.05). The &OV0312;o2 and HR responses stabilized throughout exercising at CPi (2.52 ± 0.52 L·min; 156 ± 8 b·min) and MLSSi (2.41 ± 0.32 L·min; 152 ± 10 b·min). These physiological variables were similar between conditions. However, the [Lac] and RPE were higher from the middle to the end of exercise duration at CPi ([Lac] = 6.9 ± 2.6 mM; RPE = 17.1 ± 2.1 a.u.) compared to MLSSi ([Lac] = 5.1 ± 0.9 mM; RPE = 15.7 ± 1.8 a.u.). Therefore, CPi intensity determined from 30:30 seconds of effort and rest periods on a cycle ergometer is equivalent to the MLSSi, and there is a physiological steady state throughout both exercise intensities, although the [Lac] and RPE responses at CPi are higher than at MLSSi. Thus, the CPi and MLSSi may be used as tools for intermittent training evaluation and prescription.

Critical power can be estimated from nonexhaustive tests based on rating of perceived exertion responses.

The purpose of this study was to evaluate a novel procedure, based on the perceived exertion threshold (PET) concept, involving non-exhaustive tests (PET14-17) to estimate critical power (CP), as well as to examine the reproducibility of these indices. Twenty young men performed 2 trials (Trial 1 and Trial 2) of 4 exhaustive predictive tests to estimate CP, PET, and PET14-17. The slope coefficients of the regression lines corresponding to the ratings of perceived exertion (RPE) versus time relationship (y axis) obtained during the predictive tests were plotted against the power outputs (x axis) to estimate PET. PET was calculated as the intersection point of the regression line in the power axis. The 14-17 RPE range of each predictive test was modeled using the same mathematical procedures used to estimate PET14-17. CP was derived from the power-time hyperbolic equation. Analysis of variance revealed no significant differences among CP (189-194 W), PET (190-191 W) and PET14-17, (191-195 W). The correlations between CP and PET (r = 0.87), CP and PET14-17 (r = 0.89), and PET and PET14-17 (r = 0.88) were all strong. Additionally, the bias +/- limits of agreement when plotting CP and PET was -2.16 +/- 31.60 W, and -5.70 +/- 31.21 W when comparing CP and PET14-17. Relatively high reproducibility levels of CP (ICC = 0.96), PET (ICC = 0.85) and PET14-17 (ICC = 0.83) were recorded in the test-retest fashion. It can be concluded that the PET14-17 can be utilized with relatively high accuracy and reproducibility to estimate CP without causing exhaustion in the subjects.