Effects of acute exercise performed at different times of day on respiratory, blood pressure, and cardiac autonomic modulation outcomes in patients with obstructive sleep apnea: a randomized crossover trial.

This study aimed to analyze the effect of acute aerobic exercise at different times of the day on respiratory sleep parameters, blood pressure (BP), and cardiac autonomic modulation in patients with obstructive sleep apnea (OSA). In this randomized cross-over trial, 22 patients with OSA were recruited and completed four experimental sessions in random order: aerobic exercise and control in the morning (8:00-11:00 AM) and in the afternoon (3:30-6:30 PM). Each exercise session consisted of 40 min of aerobic exercise on a treadmill at 54-59% heart rate reserve; each control session consisted of seated rest for 40 min. Measurements were taken in the supine position before and after each session for clinic and central BP and cardiac autonomic modulation (by heart rate variability). After each session, all patients underwent at-home polysomnography using a portable polygraph. Clinic and central systolic BP decreased following both morning (Clinic: -16.1 mmHg; 95%CI = -22.5--9.7 mmHg; p < 0.001; Central: -13.3 mmHg -21.6--5.0 mmHg, p = 0.002) and afternoon (Clinic: -11.4 mmHg; 95%CI = -16.8--5.9 mmHg; p = 0.03; Central: -13.9 mmHg; 95%CI = -20.1--7.7 mmHg; p < 0.001) exercise sessions; however, no significant difference was observed between sessions. No significant changes were observed regarding diastolic BP, respiratory, or heart rate variability parameters (p > 0.05 for all). In conclusion, a single session of aerobic exercise has no effect on respiratory sleep parameters but led to a similar reduction in systolic blood pressure following both morning and afternoon sessions.