Heart rate variability during dynamic exercise in elderly males and females

It has been proposed that cardiac control is altered in the elderly. Power spectral analysis of heart rate variability (HRV) was performed on 12 male and 11 female elderly subjects (mean age 74 years) while at rest in supine and sitting positions, and at steady states during 5 min of exercise (35-95 % peak oxygen consumption, (V) over dot O-2peak) There were no differences in power. measured as a percentage of the total of the high frequency peak (HF, centred at about 0.25 Hz; 13% in males vs 12% in females), low frequen cy peak (LF, centred at 0.09 Hz; 25% in males and 22% in females). and very low frequency component (VLF, at 0.03 Hz; 66% in males and 69% in females) between body positions at rest. There was no difference in spectral power between male and female subjects. Total power decreased as a function of ox ygen consumption during exercise, LF% did not change up to about 14 ml . kg (-1) . min(-1) (40% and 80% (V) over dot O-2peak in males and females, resp ectively), then decreased towards minimal values in both genders. HF% power and central frequency increased linearly with metabolic demand, reaching h igher values in male subjects than in female subjects at (V) over dot 2(pea k), while VLF% remained unchanged. Thus, the power spectra components of HR V did not reflect the changes in autonomic activity that occur at increasin g exercise intensities, confirming previous findings in young subjects, and indicated similar responses in both genders.