The response of the autonomic nervous system to passive lower limb movement and gender differences

The aim of the present study was to identify the response of the autonomic nervous system (ANS) to passive lower limb movement and to determine whether there are gender differences. The experimental sets included 5 cycles per minute (CPM5), 10 cycles per minute (CPM10) and 15 cycles per minute (CPM15) on the passive cycling machine. ANS activity was measured using heart rate variability time domain analysis (RR interval, pNN50, RMSSD and SDNN), frequency domain analysis (TF, LF, HF and LF/HF) and Poincaré plot analysis (SD1, SD2 and SD1/SD2 ratio). The collected signal at rest served as the baseline (rest). Compared with the parameters at rest, the male subjects had decreased pNN50, decreased SDNN, lower TP and LF power (ms²), suppressed LF (n.u.), augmented HF (n.u.), suppressed LF/HF, decreased SD2 and increased SD1/SD2 ratios in response to CPM5 or CPM10 (all P < 0.05). Compared with the parameters at rest, decreased LF/HF and increased SD1/SD2 in response to CPM5 or CPM10 (all P < 0.05) were the only changes in the female subjects. LF/HF and SD1/SD2 differed between both groups for the same level of passive lower limb movement (all P < 0.05). These results suggest that passive lower limb movement leads to an ANS response and that male subjects are more sensitive to passive lower limb movements. During passive leg movements, sympathetic nervous activity is largely suppressed, and vagal activity achieves dominance. The response of the ANS to passive leg movement is determined by gender.