Effects of apnea on motor and cardiac rhythms

Usually, spontaneous rhythm of movements is studied through tasks involving an increase in heart rate (HR) such as physical exercises, locomotion or mental tasks. This experiment, instead, checks whether spontaneous rhythm is influenced by HR deceleration provoked by a voluntary apnea. The performances in a motor spontaneous tempo (MST) task performed for 3 min were compared to the same finger-tapping task performed in apnea. The results show a systematic adjustment period at the beginning of each trial in order to achieve a stable MST. More interestingly, HR and MST decreased simultaneously during apnea conditions and the finger-taps occur most frequently around the ventricular systole. Assuming that apnea increases arousal level, this parallelism between cardiac and motor rhythms is in contradiction with the sympathetic hypothesis that suggested that MST is mainly influenced by arousal.