Standardized tests of heart rate variability: normal ranges obtained from 309 healthy humans, and effects of age, gender, and heart rate

The authors undertook this study to determine the effects of age, gender, a nd heart rate MR) on the results of cardiac autonomic function tests for me asuring heart rate variability (HRV) in a large sample of healthy subjects (n = 309). Conventional tests (deep breathing, maximum/minimum 30:15 ratio) , and a standardized 5-minute resting study, including spectral analysis of HR, were used. The main findings included (1) the indices of all tests, ex cept for the ratio of the low- (LF) to high-frequency (HF) spectral power ( LF/HF ratio) and HR itself, are inversely related to age in both sexes; (2) the 5-minute spectral bands (except for the LF/HF ratio), the variation co efficient, expiratory-inspiratory ratio during deep breathing, and the maxi mum/minimum 30:15 ratio are independent of HR; (3) women up to the age of 5 5 years have a higher resting HR compared with men; (4) young and middle-ag ed women show a significantly lower LF power and LF/HF ratio compared with age-matched men, whereas no significant gender differences are observed in the absolute HF power. The authors computed age- and gender-dependent norma l values for each of the HRV indices studied here and discuss the clinical consequences arising from gender differences in HRV.