Key result
Long-term high-altitude exposure is linked to ~15% lower cardio-respiratory-vascular coupling strength and increased complexity.
Why the study?
Altitude-acclimatization-related patterns of the cardio-respiratory-vascular coupling system, a core homeostasis-maintaining integrative mechanism, remain incompletely elucidated.
Does prolonged high-altitude exposure alter cardio-respiratory-vascular coupling dynamics in healthy adults?
Cross-Sectional (n=341)
Yes
Does prolonged high-altitude exposure alter cardio-respiratory-vascular coupling dynamics in healthy adults?
Prolonged high-altitude acclimatization induces a regulatory shift in cardio-respiratory-vascular coupling from linear synchrony to nonlinear complexity to maintain homeostasis.
Should not yet change clinical management at altitude; leaves open causal effects on outcomes and need for prospective validation.
Introduction: Prolonged high-altitude hypoxia induces acclimatization-related changes of multiple human physiological systems. The cardio-respiratory-vascular (CRV) coupling system, a core homeostasis-maintaining integrative mechanism, has incompletely elucidated altitude-acclimatization-related patterns. This study aimed to systematically explore CRV coupling and related physiological parameter changes across a broad altitude range in long-term acclimatized individuals. Methods: A multicenter cross-sectional study was conducted across five altitude gradients (HA0: <100 m, n=62; HA1: 1300 m, n=74; HA2: 3700 m, n=60; HA3: 4300 m, n=71; HA4: 5100 m, n=74). Synchronous electrocardiogram, hemodynamic, and respiratory signals were collected from healthy adults with ≥3 months of acclimatization. CRV coupling strength and complexity were computed, integrated with heart rate variability (HRV), hemodynamic, and respiratory parameters for analysis, with a HA4-specific physiological correlation network constructed. Results: declined and PPV rose with altitude; DBP (P = 0.0042) and MAP (P = 0.0204) increased only at HA4. Respiratory parameters exhibited asymmetric characteristics: AED and BR elevated (P<0.05), with BR_CV and EDC_CV increasing significantly only at HA4 (P<0.01). At HA4, coupling strength correlated positively with vagal activity/heart rate complexity and negatively with sympathetic dominance/respiratory variability, while complexity correlated positively with sympathetic dominance. Discussion: Long-term high-altitude acclimatization is characterized by a regulatory shift of the CRV system from strength-dominant linear synchrony to complexity-prioritized nonlinear flexibility. Extreme hypoxia may trigger enhanced nonlinear interactions to compensate for reduced linear synchrony, relying on respiratory rhythm stabilization and precise autonomic balance modulation. The findings may provide novel insights into the integrated physiology of high-altitude acclimatization.
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Liu et al. (2026) conducted a cross-sectional in Healthy adults (high-altitude acclimatization) (n=341). High altitude exposure (up to 5100 m) vs. Lowland plain site (<100 m) was evaluated on Overall cardio-respiratory-vascular coupling strength (rtotal) (p=<0.0001). Long-term high-altitude exposure at 5100 m significantly attenuated overall cardio-respiratory-vascular coupling strength (1.53 vs 1.81, P<0.0001) and increased coupling complexity compared to lowland baseline.
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