Acute Effects of Interrupting Prolonged Sitting With Intermittent Physical Activity on Blood Pressure in...

To compare the acute effects of intermittent physical activity (PA) across 4 different intensities on blood pressure.

Thirty children (12 males and 18 females; aged 7-11 y; 33% overweight/obese; 53% nonwhite) completed 4 experimental conditions in random order: 8 hours sitting interrupted with 20, 2-minute low-, moderate-, high-intensity PA breaks, or sedentary screen-time breaks. PA intensity corresponded with 25%, 50%, and 75% of heart rate reserve. Blood pressure was measured during each condition in the morning (0800 h), noon (1200 h), and afternoon (1600 h).

There were no significant differences across conditions for systolic blood pressure (SBP; all Ps > .05). There was a significant effect of time with SBP decreasing throughout the day for all conditions (average morning SBP: 106 [1] mm Hg, average noon SBP: 101 [2] mm Hg, average afternoon SBP: 103 [1] mm Hg; P = .01). There were no significant effects of condition or time on diastolic blood pressure (all Ps > .05).

While sedentary behavior is known to be associated with hypertension in both adults and children, a single bout of prolonged sitting may be insufficient to produce hypertensive effects in otherwise healthy children. Future research should examine the appropriate dose of intermittent PA to accrue hypotensive responses in preadolescent children.