Taking Short Walking Breaks Reverses Negative Effects of Prolonged Sitting

Taking Short Walking Breaks Reverses Negative Effects of Prolonged Sitting

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Title: Effect of Prolonged Sitting and Breaks in Sitting Time on Endothelial Function

Author: Thosar et al

Journal: Medicine & Science in Sports & Exercise

Objective: To examine the effects of breaking sitting time on superficial femoral artery endothelial function.

Background

In the modern society, many folks at their day jobs find themselves seated for long periods of time. Additionally, with the increased availability of television and computers, seated activity at home is on the rise. In fact, the average American sits for about 8 hours per day.

When people walk around, the contracting muscles of the lower extremities facilitate pumping blood back to the heart and keep the blood of the body flowing smoothly. When people sit, those muscles are not contracting as effectively and their ability to pump blood back to the heart is limited. This allows blood to pool in the legs, which limits the ability of the blood vessels to do their job.

Prolonged sitting is associated with increased risk of a variety of things

  • Heart attack
  • High cholesterol
  • Metabolic syndrome
  • Obesity
  • Colon cancer
  • Death from cancer
  • Increased overall mortality
  • Worsening mental health
  • Increased risk of disability
  • Muscle atrophy
  • Weakened bone structure
  • Blood clots in legs (DVT)
  • Back pain
  • And more…

Methods

This study included 12 nonobese men who participated in two randomized 3 hour sitting trials.

  • Sitting trial: seated firmly on cushioned chair for 3 hours without moving lower extremities
  • Breaking sitting time trial: similar seating to sitting trial, however they walked on a treadmill for 5 minutes at 30 minutes, 90 minutes and 150 minutes during that 3 hour period.

The authors measured superficial femoral artery flow mediated dilation at baseline, and every hour of the study up to 3 hours. Flow mediated dilation is a way of describing expansion of the arteries as a result of increased blood flow.

Results

In the sitting trial, flow mediated dilation diminished rapidly from baseline. (baseline: 4.72±3.78%, 1hr: 0.52±0.85%, 2hr: 1.66±1.11%, 3hr: 2.2±2.15; p<0.05 by ANOVA).

When the participants took 5 minute walks, this prevented the sitting-induced decline in flow mediated dilation from baseline. (baseline: 4.5±2.3%, 1hr: 5.04±2.85%, 2hr: 5.28±5.05%, 3hr: 6.9±4.5%).

Conclusions

First, 3 hours of uninterrupted sitting resulted in significant decline in flow mediated dilation.

When 5 minute activity breaks were introduced hourly during sitting, the decline in flow mediated dilation was reduced by as much as 50%.

The results of this study suggest that light exercise breaks during prolonged periods of sitting can reduce pooling of blood in lower extremities and may have implications for risk factors associated with prolonged sitting.

Original Article

Thosar, S. S., Bielko, S. L., & Mather, K. J. (2015). Effect of Prolonged Sitting and Breaks in Sitting Time on Endothelial Function. Medicine & Science in Sports & Exercise, 47(4), 843-849. doi:10.1249/mss.0000000000000479

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