Post-exercise blood pressure reduction is greater following intermittent than continuous exercise and is influenced less by diurnal variation.

Recently, we reported that circadian variation exists in the response of blood pressure (BP) following a bout of uninterrupted exercise. The usual phenomenon of post-exercise hypotension was absent or reversed when such exercise was performed between 04:00-08:00 h. Nevertheless, research examining BP changes following bouts of intermittent exercise at different times of the day is scarce, even though this type of activity is probably more popular. Therefore, we aimed to compare post-exercise BP reductions of continuous (CONT) and intermittent (INT) exercise protocols performed at 08:00 h and 16:00 h. At both of these times of day, eight normotensive males completed 30 min of continuous cycling in the CONT and three 10 min bouts of cycling separated by 10 min of rest in the INT protocol. The exercise intensity was set at 70% (.)VO(2peak) during both protocols. Heart rate, systolic (S) and diastolic (D) BP, and mean arterial pressure (MAP) were measured 5 min before and 20 min after exercise. Changes from pre-exercise baseline were analyzed using linear mixed modeling. MAP was 8+/-1 mm Hg lower following INT compared with CONT exercise (p<0.05). SBP and DBP were also significantly lower following INT compared with CONT exercise (p<0.05). Diurnal variation in MAP was evident, with attenuated hypotension being observed after morning exercise (p<0.05), although this diurnal variation was less marked following INT compared with CONT exercise (p<0.05). We conclude that intermittent exercise mediates greater post-exercise hypotension compared with a single continuous bout of equivalent work and that this protocol-dependent difference is greatest in the afternoon. Therefore, a bout of afternoon exercise that is occasionally interrupted with short rest periods is recommended for lowering BP acutely.