Evaluation of nocturnal heart rate variability for strenuous exercise day using wearable photoelectric pulse wave sensor

In this study, we examined whether or not the strenuous exercise in the evening change nocturnal heart rate variability (HRV) and recovers. Subjects were 8 healthy men belonging to the mature futsal team (age: 35±3 years) and Futsal was held from 5:00 p.m. to 6:30 p.m. on Sunday. Pulse waves during sleeping were measured at home on exercise day and on control day. The mean pulse interval (MPI), standard deviation pulse interval (SDPI), low frequency component (LF, 0.04-0.15 Hz), high frequency component (HF, 0.15-0.45 Hz) and the ratio of LF to HF (LF/HF) were calculated from pulse interval time series every 30 min. As a re-sult, MPI, SDPI, LF, HF of exercise day were significantly lower than control day (P < 0.0001). LF/HF of exercise day was significantly higher than control day (P < 0.05). Regarding change of HRV for every 30 min, MPI (P < 0.05), SDPI (P=0.0003), LF (P=0.0038), HF (P < 0.05) were ob-served significant changes. MPI and HF before wake-up did not reach the level of control day. It is thought that strenuous exercise in the eve-ning promotes sympathetic nervous activity during night sleep and sug-gesting that pulse rate and HRV have not recovered by the wake-up time.