Heart rate variability during dynamic exercise in supine position in sedentary subjects

The power spectral analysis of heart rate variability (HRV) was assessed during dynamic exercises at different intensities while pedaling in both the orthostatic (O) and clinostatic (C) positions. In addition to a decrease in HRV, with increasing work load high-frequency (HF) peak shifts to higher frequencies in both the O and C positions, reflecting increased ventilation. With increasing exercise intensity, the low frequency (LF) peak decreases toward negligible values in the O position while it increases the C position. A combined effort of gravity and vasodilatation could be responsible for the disappearance of the LF peak in the O position