HRV and blood parameters for assessing the physiological functioning of cyclists during long-distance rides across different altitudes

This study systematically evaluated the dynamic changes in HRV and hematological parameters in cyclists during prolonged exposure to different altitudes. The results showed that at moderate altitude, athletes exhibited a coordinated response of enhanced short-term autonomic adaptation and increased red blood cell volume. At very high altitude, HRV decreased overall while its complexity increased, indicating a stress-compensatory mechanism dominated by sympathetic activation. Altitude-specific correlations between HRV and blood parameters suggest a potential interplay between autonomic regulation and hematological adaptation.