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Breaks in Sitting Time: Effects on Continuously Monitored Glucose and Blood Pressure


Medicine & Science in Sports & Exercise: October 2017 - Volume 49 - Issue 10 - p 2119–2130
doi: 10.1249/MSS.0000000000001315
Applied Sciences

Purpose We examined the effects of interrupting prolonged sitting with multiple 2-min walking breaks or one 30-min continuous walking session on glucose control and ambulatory blood pressure (ABP).

Methods Ten overweight/obese, physically inactive participants (five men; 32 ± 5 yr; BMI, 30.3 ± 4.6 kg·m−2) participated in this randomized four-trial crossover study, with each trial performed on a separate, simulated workday lasting 9 h: 1) 30 min of continuous moderate-intensity (30-min MOD) walking at 71% ± 4% HRmax; 2) 21 × 2 min bouts of moderate-intensity (2-min MOD) walking at 53% ± 5% HRmax, each performed every 20 min (42 min total); 3) 8 × 2 min bouts of vigorous-intensity (2-min VIG) walking at 79% ± 4% HRmax, each performed every hour (16 min total); 4) 9 h of prolonged sitting (SIT). Participants underwent continuous interstitial glucose monitoring and ABP monitoring during and after the simulated workday spent in the laboratory, with primary data analysis from 12:30 h to 07:00 h the next morning.

Results Compared with SIT (5.6 ± 1.1 mmol·L−1), mean 18.7-h glucose was lower during the 2-min MOD (5.2 ± 1.1 mmol·L−1) and 2-min VIG (5.4 ± 0.9 mmol·L−1) trials and mean 18.7-h glucose during the 30-min MOD trial (5.1 ± 0.8 mmol·L−1) was lower than all other trials (P < 0.001). Postprandial glucose was approximately 7% to 13% lower during all trials compared with SIT (P < 0.001), with 30-min MOD having the greatest effect. Only the 30-min MOD trial was effective in reducing systolic ABP from 12:30 to 07:00 h (119 ± 15 mm Hg) when compared with SIT (122 ± 16 mm Hg; P < 0.05).

Conclusions Replacing sitting with 2-min MOD walking every 20 min or 2 min of vigorous-intensity walking every hour during a simulated workday reduced 18.7 h and postprandial glucose, but only 30-min MOD walking was effective for reducing both glucose and systolic ABP.

Supplemental digital content is available in the text.

1Exercise Science and Health Promotion, Healthy Lifestyles Research Center, Arizona State University, Phoenix, AZ; 2College of Nursing and Health Sciences, School of Health Sciences, Valdosta State University, Valdosta, GA; 3Departments of Kinesiology and Biology, Point Loma Nazarene University, San Diego, CA; and 4Department of Kinesiology, University of Texas at Arlington, Arlington, TX

Address for correspondence: Glenn Gaesser, Ph.D., School of Nutrition and Health Promotion, Arizona State University, 550N 3rd Street, Phoenix, AZ 85004; E-mail:

Submitted for publication November 2016.

Accepted for publication April 2017.

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© 2017 American College of Sports Medicine