The Relationship Between VO₂ Max and Heart Rate Variability Parameters in Individuals with High Risk for...

The purpose of this study was to evaluate the relationship between heart rate variability (HRV) parameters, classified into frequency and time domains, and maximal oxygen uptake (VO₂ max) in individuals at high risk of cardiovascular disease but without a clinical diagnosis.

Based on a 10-year atherosclerotic cardiovascular disease risk score, 311 patients at high cardiovascular risk were included in this retrospective analysis. The study population was divided into tertiles according to VO₂ max values. Demographic, clinical, echocardiographic, laboratory and HRV data were compared across tertiles. The associations between VO₂ max and HRV parameters including standard deviation of normal-to-normal (NN) intervals over 24 hours, standard deviation of the averages of NN intervals in all 5-minute segments, standard deviation of NN intervals in 5-minute segments (SDNN index), root mean square of successive differences (rMSSD), percentage of successive NN intervals that differ by more than 50 ms, total power (TP), low frequency (LF), and high frequency (HF) were analyzed using Spearman correlation analysis.

VO₂ max showed a moderate correlation with TP, LF and HF (rho = 0.211, p < 0.001; rho = 0.181, p = 0.001; and rho = 0.361, p < 0.001, respectively). In addition, significant correlations were found between VO₂ max and rMSSD (rho = 0.122, p = 0.032) and SDNN index (rho = 0.184, p = 0.001). These associations remained statistically significant after adjusting for age using partial Spearman correlation analysis.

This study demonstrated significant correlations between HRV frequency and time domains with VO₂ max in asymptomatic individuals with high cardiovascular risk.