Heart rate fragmentation as a marker of autonomic function in healthy young individuals: insights from graded head-up tilt test and controlled breathing

Figures

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  Figure 1. Percentage of inflection points (PIP) at baseline and during graded head-up tilt (15°, 45°, and 75°). Data are presented as median and interquartile range with individual data points. Statistical comparisons were performed using one-way repeated-measures analysis (Friedman test) followed by Dunn’s post hoc test. p < 0.05 vs. baseline (a); p < 0.05 vs. baseline and 15° (b).

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  Figure 2. Occurrence (%) of symbolic patterns with zero (W0), one (W1), two (W2), and three (W3) inflection points at baseline and during graded head-up tilt (15°, 45°, and 75°). Data are presented as median and interquartile range. Statistical comparisons were performed using one-way repeated-measures analysis (Friedman test) followed by Dunn’s post hoc test. p < 0.05 vs. Baseline and 15° (b).

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  Figure 3. Occurrence (%) of symbolic patterns with hard (WH), soft (WS), and mixed (WM) inflection points at baseline and during graded head-up tilt (15°, 45°, and 75°). Data are presented as median and interquartile range. Statistical comparisons were performed using one-way repeated-measures analysis (Friedman test) followed by Dunn’s post hoc test. p < 0.05 vs. Baseline and 15° (b).

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  Figure 4. Scatter plots illustrating the relationship between the percentage of inflection points (PIP) and 0V% (left panel) and 2UV% (right panel) across all experimental conditions. Each symbol represents an individual observation. Spearman’s correlation coefficient (r) is indicated in each panel.

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  Figure 5. Percentage of inflection points (PIP) during spontaneous and controlled breathing. Data are presented as median and interquartile range with individual data points. Statistical comparison was performed using a Wilcoxon signed-rank test. p < 0.05 vs. spontaneous breathing (α).

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  Figure 6. Occurrence (%) of symbolic patterns with zero (W0), one (W1), two (W2), and three (W3) inflection points during spontaneous and controlled breathing. Data are presented as median and interquartile range. Statistical comparisons were performed using a Wilcoxon signed-rank test. p < 0.05 vs. spontaneous breathing (α).

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  Figure 7. Occurrence (%) of symbolic patterns with hard (WH), soft (WS), and mixed (WM) inflection points during spontaneous and controlled breathing. Data are presented as median and interquartile range. Statistical comparisons were performed using a Wilcoxon signed-rank test. p < 0.05 vs. spontaneous breathing (α).

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  Figure 8. Scatter plots illustrating the relationship between the percentage of inflection points (PIP) and 2LV% (left panel) and 2UV% (right panel) during spontaneous and controlled breathing. Each symbol represents an individual observation. Spearman’s correlation coefficient (r) is indicated in each panel.