Peak Cardiac Mechanical and Haemodynamic Responses During Incremental Exercise Are Temporally Associated With Ventilatory Thresholds: Novel Insight Into the Coordination of Integrative Physiological Responses to Exercise

Figures

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  FIGURE 1. Associations between ventilatory thresholds and selected cardiovascular plateau timing. Scatterplots show associations between relative HR at ventilatory thresholds and relative HR at plateau formation of selected cardiac deformation and peripheral haemodynamic parameters. VT1 associations are shown in blue and VT2 in green. Left panels display VT1‐related associations; right panels display VT2‐related associations. Solid lines represent linear regression fits with 95% confidence intervals (dashed). Pearson's r or Spearman's ρ (according to distribution), corresponding p‐values, and sample sizes are indicated within each panel.

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  FIGURE 2. Associations between VO2peak and selected cardiovascular plateau timing. Scatterplots illustrating associations between VO2peak and plateau timing (PT, expressed as %HRmax) of selected cardiac deformation and haemodynamic parameters. Upper panels show associations with iCarT, twist, and apical rotation (red). Lower panels show associations with stroke volume (SV; purple), ejection fraction (EF; purple), and systemic vascular resistance (SVR; cyan). Solid lines represent linear regression fits and dashed lines indicate 95% confidence intervals. Pearson correlation coefficients (r) or Spearman rank correlation coefficients (ρ), along with p‐values and sample sizes, are reported in each panel.

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  FIGURE 3. Associations between VO2peak and resting/peak cardiac function. Associations of VO2peak with selected cardiovascular variables at rest (black) and at peak exercise (red). Solid lines denote linear regression fits; dashed lines indicate 95% confidence intervals. Pearson correlation coefficients (r), p‐values, and sample sizes (N) are reported within each panel.

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  FIGURE 4. Schematic representation of exploratory cluster‐specific plateau‐timing profiles and association with VO2peak. (A) Schematic representation of the two exploratory plateau‐timing clusters. X‐axis represents %HRmax from 50% to 100%. Volumetric PT includes EDV, ESV, SV, and EF. Cluster 1 (higher VO2peak; dissociated profile) showed earlier volumetric plateau timing but later plateau timing of selected rotational mechanics, particularly twist and untwisting. In contrast, Cluster 2 (lower VO2peak; compressed profile) showed later volumetric plateau timing, while twist and untwisting plateaued earlier and in closer temporal proximity to the volumetric domain. The clustering analysis is intended as a descriptive visualization of interindividual variability. (B) Individual VO2peak values by cluster, shown with group summary. Cluster 1 exhibited a higher VO2peak than Cluster 2 (p = 0.0077).