Exercise intensity and blood pressure during sleep

Exercise, of appropriate intensity and duration, could help maintain normotension if post-exercise hypotension persists over subsequent everyday activities. Therefore, we monitored ambulatory blood pressure (BP) for 24 h following four separate exercise bouts which differed in intensity, duration and total work completed. At 08:00 h, six normotensive males completed a no exercise control and, in two further trials, 30 min of cycling at 70% V̇O_2peak and 40% V̇O_2peak. A fourth trial involved cycling at 40% V̇O_2peak for a time which equated total work with that in the most intense exercise trial. Between 20 min and 24 h after exercise, ambulatory BP, heart rate (HR) and wrist-activity were compared between trials using general linear models. Participants slept normally at night. Post-exercise changes in BP and HR were not affected by exercise intensity or total work completed from 20 min after exercise until nocturnal sleep-onset (p > 0.21). During sleep, mean arterial BP was lower following exercise at 70% V>O_2peak compared to the other trials (p = 0.03), including the 40% V>O_2peak trial equated for total work (90% CI for difference = - 22.1 to - 0.1). We conclude that daytime exercise can elicit a physiologically meaningful lower BP during sleep and exercise intensity is the most important factor in this phenomenon.