Time of day for exercise on blood pressure reduction in dipping and nondipping hypertension
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 (BP24 h) reduction than PMex in Dippers, and (4) AMex and PMex would exhibit similar BP24 h reduction in Non-Dippers. BP responses to AMex (0600–0800 h; 30 min at 50% VO2peak) and PMex (1700–1900 h) were compared to each control day in a randomized design. Systolic (S) and diastolic (D) BP were averaged for BP24 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 SBP24 h 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.