Cardiorespiratory and metabolic stress responses to acute high-intensity interval training anchored to critical power or maximal heart rate

Figures

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  Fig. 1. Study CONSORT diagram.

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  Fig. 2. Workload data. (a) Mean workload during each trial. (b) Distribution of participants’ prescribed HIIT workloads relative to individual CP between conditions. Data in (a) are mean ± SD (n = 19). HRHIIT = heart rate-based experimental condition; CPHIIT = critical power-based experimental condition. *p < 0.05.

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  Fig. 3. Capillary blood lactate data. (a) Variability of change in [blood lactate], determined from the net change in [blood lactate] from rest to the end of exercise (i.e. after Bout 4). (b) Absolute blood [lactate] accumulation between rest and the end of exercise. (c) Blood [lactate] at rest and at the end of exercise. Data for (a) is presented as median (interquartile range), and (b) and (c) are mean ± SD (n = 19). HRHIIT = heart rate-based experimental condition; CPHIIT = critical power-based experimental condition. #p < 0.05 vs. Rest, main effect for time.

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  Fig. 4. Last 30 s oxygen uptake data. Final 30 s \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}$$\end{document}O2 during Bout 1 and Bout 4 in each trial. All data are mean ± SD (n = 19). HRHIIT = heart rate-based experimental condition; CPHIIT = critical power-based experimental condition. *p < 0.05 vs. HRHIIT, main effect for condition. #p < 0.05 vs. Bout 1, main effect for time.

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  Fig. 5. Heart rate and rating of perceived exertion data. (a) Peak exercise heart rate relative to individual maximal exercise heart rate between experimental conditions. (b) Rating of perceived exertion at the end of each bout during experimental HIIT trials. Data are reported as mean ± SD (n = 18 for CPHIIT in Bout 2 only, n = 19 for rest). HR = heart rate; HRmax = maximal exercise heart rate; RPE = rating of perceived exertion; HRHIIT = heart rate-based experimental condition; CPHIIT = critical power-based experimental condition. *p < 0.05 vs. HRHIIT, main effect for condition. #p < 0.05 main effect for time.