Changes in heart rate, the ratio of low-frequency component to high-frequency component of the heart rate variability spectrum (LF/HF), and high-frequency component of the heart rate variability spectrum normalized by total power (HF
). PWM: passive walking-like leg movement. QS: quiet standing. *P < 0.05, **P < 0.01, ***P < 0.001 compared to the sitting baseline level; #P < 0.05, ##P < 0.01, ###P <0.001 compared to the quiet standing baseline level; †P < 0.05, †† P < 0.01, †††P < 0.001 for comparison between values in the PWM and QS trials.