Resting heart rate variability and cardiorespiratory fitness in healthy young adults

Background Heart rate recovery (HRR) following maximal or submaximal exercise and Metabolic Equivalents (METs) reflect cardiovascular fitness. In the present study resting Heart Rate Variability (HRV) measures, HRR following submaximal exercise and METs were correlated. Methods Sixty two healthy volunteers in the age group of 18–24 years were subjected to short term baseline HRV evaluation in frequency domains and submaximal treadmill test . Percentage of HRR following exercise protocol and METs were estimated. Results Mean age of study population (male = 30, female = 30) was 20 ± 1.80 years with mean body mass index of 22.55 ± 3.80 kg/m 2 . HRV measures were correlated with post exercise HRR and METs. Analysis showed a significant positive correlation between post exercise HRR at 2nd minute and high frequency when expressed in absolute ( r = 0.324, p < 0.05) and normalized units ( r = 0.317, p < 0.05) which reflects cardiac vagal activity . Significant negative correlation was found between HRR at 2nd minute and low frequency power in normalized unit ( r = −0.29, p < 0.05) which is modulated by sympathetic and parasympathetic systems. Further the total power which is the surrogate of overall autonomic modulation also has significant correlation (total power- r = 0.303, p < 0.05) with METs. Conclusions Resting HRV measures are associated with cardiorespiratory fitness as assessed by HRR immediately after exercise and METs in healthy young adults.