Morning aerobic exercise produced a significantly greater net reduction in systolic blood pressure (-7 ±3 mmHg) compared to evening exercise (-3 ±4 mmHg) when controlling for circadian variations.
RCT (n=16)
Simple randomization
No
Does aerobic exercise performed in the morning versus the evening improve post-exercise hypotension in pre-hypertensive men?
Morning aerobic exercise produces a greater systolic post-exercise hypotensive effect than evening exercise in pre-hypertensive men when accounting for circadian blood pressure variations.
Absolute Event Rate: -7% vs -3%
p-value: p=<0.05
Post-exercise hypotension (PEH), calculated by the difference between post and pre-exercise values, it is greater after exercise performed in the evening than the morning. However, the hypotensive effect of morning exercise may be masked by the morning circadian increase in blood pressure. This study investigated PEH and its hemodynamic and autonomic mechanisms after sessions of aerobic exercise performed in the morning and evening, controlling for responses observed after control sessions performed at the same times of day. Sixteen pre-hypertensive men underwent four sessions (random order): two conducted in the morning (7:30 am) and two in the evening (5 pm). At each time of day, subjects underwent an exercise (cycling, 45 min, 50%VO2peak) and a control (sitting rest) session. Measurements were taken pre- and post-interventions in all the sessions. The net effects of exercise were calculated for each time of day by (post-pre exercise)-(post-pre control) and were compared by paired t-test (P<0.05). Exercise hypotensive net effects (e.g., decreasing systolic, diastolic and mean blood pressure) occurred at both times of day, but systolic blood pressure reductions were greater after morning exercise (-7±3 vs. -3±4 mmHg, P<0.05). Exercise decreased cardiac output only in the morning (-460±771 ml/min, P<0.05), while it decreased stroke volume similarly at both times of day and increased heart rate less in the morning than in the evening (+7±5 vs. +10±5 bpm, P<0.05). Only evening exercise increased sympathovagal balance (+1.5±1.6, P<0.05) and calf blood flow responses to reactive hyperemia (+120±179 vs. -70±188 U, P<0.05). In conclusion, PEH occurs after exercise conducted at both times of day, but the systolic hypotensive effect is greater after morning exercise when circadian variations are considered. This greater effect is accompanied by a reduction of cardiac output due to a smaller increase in heart rate and cardiac sympathovagal balance.
Brito et al. (Fri,) conducted a rct in Pre-hypertension (n=16). Morning aerobic exercise (cycling) vs. Evening aerobic exercise (cycling) was evaluated on Net effect of exercise on systolic blood pressure (mmHg) (p=<0.05). Morning aerobic exercise produced a significantly greater net reduction in systolic blood pressure (-7 ±3 mmHg) compared to evening exercise (-3 ±4 mmHg) when controlling for circadian variations.