time of day (TOD) for exercise may influence blood pressure (BP) reduction in hypertension because of the diurnal variation of BP and the duration of BP reduction following a single bout of exercise. The purpose of this study was to observe the effects of TOD for exercise on ambulatory blood pressure reduction in dipping (n = 5) and nondipping (n = 9) hypertension (< 10% drop in nighttime BP (BPnight)). HYPOTHESES: (1) evening exercise (PMex) would exhibit a greater BPnight reduction in Non-Dippers than Dippers, (2) morning exercise (AMex) would exhibit similar daytime BP (BPday) reduction in Dippers and Non-Dippers, (3) AMex would exhibit greater 24 h BP (BP-24 h) reduction than PMex in Dippers, and (4) AMex and PMex would exhibit similar BP-24 h reduction in Non-Dippers. BP responses to AMex (0600 to 0800 h; 30 min at 50% VO2peak) and PMex (1700 to 1900 h) were compared to each control day in a randomized design. Systolic (S) and diastolic (D) BP were averaged for BP-24 h, BPday, and BPnight. A two-way ANOVA (dipping x time of exercise) using BP reduction with repeated measures were performed at p < 0.05. FINDINGS: (1) Non-Dippers respond to exercise despite of TOD for exercise, (2) PMex exhibited a greater SBPnight reduction in Non-Dippers than Dippers, (3) AMex exhibited similar SBPday reductions in Dippers and Non-Dippers, and (4) AMex and PMex exhibited similar SBP-24h reduction in Dippers and Non-Dippers. Dippers and Non-Dippers respond differently to TOD for exercise. The duration of the BP reduction persists up to 24 h after exercise.
Reprinted by permission from Journal of Human Hypertension, Macmillan Publishers Ltd.

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