Threshold estimation in running using dynamical correlations of RR intervals

Figures

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  FIGURE 1. Illustration of the DDFA thresholds (cyan vertical lines) compared to the lactate thresholds (black vertical lines) as a function of binned heart rate (HR). The integrated scaling exponent α~HRbin and the lactate concentration as a function of binned HR are represented with the black line and pink line, respectively.

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  FIGURE 2. Illustration of the behavior of integrated scaling exponent α~t (black line) and the lactate concentration (cyan line) during the exercise as a function of time. The lactate thresholds are plotted with cyan vertical lines, and the gray line corresponds to heart rate during the exercise.

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  FIGURE 3. Aggregate plot of the DDFA scaling exponents for all studied subjects as a function of normalized lactate concentration. The black line corresponds to the integrated scaling exponent α(Lanorm).

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  FIGURE 4. Bland–Altman plots of the differences between (a) HRmaxtheor T1 and LT1, (b) HRmaxtheor T2 and LT2, (c) HRmaxmeas T1 and LT1, (d) HRmaxmeas T2, and LT2, (e) DDFAT1 and LT1, and (f) DDFAT2 and LT2. The black solid lines correspond to the difference of 0 BPM, blue solid lines correspond to the mean differences and the blue dashed lines correspond to the 95% limits of agreement (= ± 1.96× standard deviation (SD)) of the studied set of data.

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  FIGURE 5. The error of the estimation for each of the compared method for (a) first lactate threshold, and (b) second lactate threshold. The boxenplots correspond to the mean differences of the estimates, and the red lines correspond to the 95% confidence intervals (CI) after bias‐corrected and accelerated (BCa) bootstrapping (104 times).