Do snacks of exercise lower blood pressure? A randomised crossover trial.

AIM: To assess whether four 10-minute 'snacks' of exercise per day are as effective at lowering blood pressure as 40 minutes of continuous moderate exercise, when compared with no exercise. METHOD: Single blind randomised crossover trial of three 'exercise' regimes in general practice. PARTICIPANTS: 35 hypertensive adults without complications. INTERVENTIONS: Regimes included 4x10-minute episodes of brisk walking per day, 40 minutes continuous brisk walking per day, and no brisk walking. Each regime lasted 4 days with 10 days of no exercise in between. OUTCOMES: Change of systolic and diastolic blood pressure. RESULTS: Mean age 53 years and mean baseline blood pressure 166/103 mmHg. Systolic blood pressure changed by: -7.5 mmHg (95%CI: -8.9, -6.0) with 40-minutes regime; -7.3 mmHg (95%CI: -8.7, -5.8) with 4x10-minutes regime; and +1.0 mmHg (95%CI: -0.4, 2.5) with 'no brisk walking' regime (p<0.001). Diastolic blood pressure reduced by -4.0 mmHg (95%CI: -5.0, -3.0) with 40 minutes regime; -5.4 mmHg (95%CI: -6.4, -4.4) with 4x10 minutes regime; and -0.2 mmHg (95%CI: -1.2, 0.8) with 'no brisk walking' regime (p<0.001). CONCLUSION: Four 10-minute snacks of brisk walking were as effective as 40 minutes of continuous brisk walking per day at reducing blood pressure. This has implications for public health messages and advice to patients with hypertension.