Published in Medicine & Science in Sports & Exercise (2012; www.ncbi.nlm.nih.gov/pubmed/22776874), the study compared the effects of different exercise bouts on blood pressure over a 24-hour period. Scientists recruited 11 hypertensive individuals around 28 years old. Each was randomly selected to participate in one of the following protocols: one 30-minute continuous exercise session; three 10-minute exercise sessions evenly spaced throughout the day; or no exercise (the control option). The mode of exercise in each case was treadmill walking at 75%–79% of heart rate maximum. Subjects were monitored with an automated ambulatory blood pressure (ABP) device for 24 hours.
So which protocol yielded the best results?
Both protocols were associated with lower systolic blood pressure than the control option during daytime and evening hours (1:00–11:00 pm). However, subjects who completed the three short bouts also had lower blood pressure overnight (11:00 pm–8:00 am) and the following morning (8:00 am–noon). This could not be said of the single-bout group.
“In prehypertensive individuals, fractionized exercise (e.g., three 10-minute aerobic exercise sessions spread out evenly throughout the day) reduces 24-hour systolic ABP by more than a single 30-minute exercise session,” the authors reported. “Fractionized exercise may be a viable and effective exercise alternative to continuous exercise for cardiovascular risk reduction in this population.”