Contact Sensors to Remote Cameras: Quantifying Cardiorespiratory Coupling in High-Altitude Exercise Recovery

TL;DR

This study investigates how cardiorespiratory coupling varies at high altitude during rest and recovery, and demonstrates the feasibility of non-contact measurement using remote photoplethysmography with strong correlation to traditional methods.

Contribution

It provides new insights into CRC behavior at high altitude and introduces a validated contactless measurement approach using rPPG technology.

Findings

CRC differs significantly between rest and recovery at high altitude

Recovery involves more frequent but less stable synchronization episodes

Remote photoplethysmography correlates strongly with oximeter-based metrics (r=0.96)

Abstract

Cardiorespiratory coupling (CRC) captures the dynamic interaction between the cardiac and respiratory systems--an interaction strengthened by physical exercise and linked to improved physiological function. We examined CRC at high altitude in two states, rest and post-exercise recovery, and found significant differences (p < 0.05). Quantitative analysis revealed that recovery involved more frequent yet less stable episodes of synchronization between respiration and pulse. Furthermore, we explored the feasibility of non-contact CRC measurement with remote photoplethysmography (rPPG), observing a strong correlation with oximeter-based metrics (Pearson r = 0.96). These findings highlight the potential of CRC as a sensitive marker for autonomic regulation and its future application in contactless monitoring. Source code is available at GitHub: https://github.com/McJackTang/CRC.