Background: The minimum duration of exercise needed to acutely lower blood pressure (BP) has not been established. The purpose of this study is to compare the effects of short and long duration on the BP response to a session of aerobic exercise.
Methods: Subjects were 45 men (mean +/- SEM, 43.4 +/- 1.5 years) with elevated BP (144.6 +/- 1.6/85.2 +/- 1.1 mm Hg). Using a parallel design, men were randomly assigned to 40% (LITE, n = 23) or 60% (MOD, n = 22) of maximal oxygen consumption. Following assignment, they completed 3 experiments: a no-exercise control, and a 15-minute SHORT and 30-minute LONG cycle bout. Subjects left the laboratory wearing an ambulatory BP monitor. Repeated measure analysis of variance tested if BP differed among experimental conditions (no-exercise control, LONG, and SHORT) and over time within groups (LITE and MOD).
Results: For 9 hours, systolic BP increased from baseline after all conditions (P < .001); however, systolic BP was reduced by 5.6 +/- 2.0 and 4.3 +/- 1.6 mm Hg after SHORT and LONG with LITE, and 4.1 +/- 1.6 and 4.9 +/- 1.9 mm Hg with MOD, respectively, compared with no-exercise control (P < .05). For 9 hours, diastolic BP (DBP) decreased from baseline after all conditions (P < .001). DBP was reduced by 2.1 +/- 1.0 and 3.6 +/- 1.4 mm Hg after SHORT and LONG with MOD for 3 hours (P < .05), and average DBP was lower by 2.4 +/- 1.0 mm Hg after LONG with LITE for 9 hours versus no-exercise control (P < .05).
Conclusions: The immediate BP-lowering effects of short-duration, lower intensity exercise are comparable to those of higher amounts of exercise. Additional investigation is needed to better quantify the dose of exercise needed to lower BP.