Investigating the Acute Effect of Different Training Protocols on Heart Rate Variability

Figures

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  Figure 1. Overview of the Study Design and Timeline. Schematic representation of the experimental protocol used to evaluate acute heart rate variability (HRV) responses to endurance training (ET) and high-intensity interval training (HIIT) in elite Greco-Roman wrestlers. Daily HRV monitoring was conducted throughout the training camp. Key measurements were taken at four time points: baseline (BASE), immediately before training (PRE), during training (TRAINING), and 24 h post-exercise (POST 24 h). The timeline reflects the sequence of training interventions and HRV assessments used to compare autonomic responses and recovery profiles across training modalities.

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  Figure 2. Change in SDNN Over Time by Training Type. (A) Individual participant trajectories (n = 13 per protocol) across four time points (BASE, PRE, TRAINING, POST 24 h), with protocol mean ± SE overlaid for ET and HIIT. (B) Distribution of SDNN (ms) at each time point by training type, shown as box plots with individual data points overlaid. Main effect of Timepoint: p < 0.001. Main effect of Training Type: p = 0.011. Post hoc between-protocol comparisons: not significant at any timepoint.

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  Figure 3. Change in RMSSD Over Time by Training Type. (A) Individual participant trajectories (n = 13 per protocol) across four time points (BASE, PRE, TRAINING, POST 24 h), with protocol mean ± SE overlaid for ET and HIIT. (B) Distribution of RMSSD (ms) at each time point by training type, shown as box plots with individual data points overlaid. Main effect of Timepoint: p < 0.001. Main effect of Training Type and Timepoint × Training Type interaction: not significant.

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  Figure 4. Change in LF/HF Ratio Over Time by Training Type. (A) Individual participant trajectories (n = 13 per protocol) across four time points (BASE, PRE, TRAINING, POST 24 h), with protocol mean ± SE overlaid for ET and HIIT. (B) Distribution of the LF/HF ratio at each time point by training type, shown as box plots with individual data points overlaid. Main effect of Timepoint: p < 0.001. Main effect of Training Type and Timepoint × Training Type interaction: not significant.

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  Figure 5. Change in lnRMSSD-derived HRV Score Over Time by Training Type. (A) Individual participant trajectories (n = 13 per protocol) across four time points (BASE, PRE, TRAINING, POST 24 h), with protocol mean ± SE overlaid for ET and HIIT. (B) Distribution of the lnRMSSD-derived HRV Score (a.u.) at each time point by training type, shown as box plots with individual data points overlaid. Main effect of Timepoint: p < 0.001. Timepoint × Training Type interaction: p = 0.008. Post hoc (TRAINING, HIIT vs. ET): p = 0.065, d = 0.79, not significant after Bonferroni correction.

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  Figure 6. Change in Heart Rate Over Time by Training Type. (A) Individual participant trajectories (n = 13 per protocol) across four time points (BASE, PRE, TRAINING, POST 24 h), with protocol mean ± SE overlaid for ET and HIIT. (B) Distribution of heart rate (bpm) at each time point by training type, shown as box plots with individual data points overlaid. Main effect of Timepoint: p < 0.001. Main effect of Training Type and Timepoint × Training Type interaction: not significant.