Most of us are deskbound at our workstation for eight hours a day, and even bind ourselves to our couches when we go home to “six and relax.” It’s no surprise we behave so in the digital age, however, since our smartphones, computers, and other gizmos encourage us to adopt a sedentary lifestyle. While prolonged sitting can lead to health risks, from metabolic syndrome to a heart attack, the negative effects of sitting may be able to be reversed with short and even slow three five-minute walks, according to a study published online in the journal Medicine & Science in Sports & Exercise. But how effective can this really be?
When we remain stationary at our desks, the slack muscles do not contract to effectively pump blood to the heart. This can lead to blood pooling in the legs and affects the endothelial function of arteries, or the ability of blood vessels to expand from increased blood flow. A decrease in blood flow can lead to fatty acids collecting in blood vessels, including the heart tissue, while also limiting the amount of oxygen and nutrients supplied to the brain.
"Walking definitely increases blood flow in the legs," said Saurabh Thosar, a postdoctoral researcher at Oregon Health and Science University, who led the study as a doctoral candidate at IU’s School of Public Health-Bloomington, The Washington Post reported. "If it's static and people are not moving, perhaps people are still not using their muscles as much as during walking." Prior to Thosar’s study, there was a lack of experimental evidence that shows prolonged sitting time can lead to various chronic diseases.
To examine the effects of breaking sitting time on superficial femoral artery (SFA) endothelial function, Thosar and his colleagues recruited a total of 12 non-obese men, between the ages of 20 and 35, to participate in two randomized three-hour sitting trials. In one trial, the participants sat for three hours without moving their legs as the researchers used a blood pressure cuff and ultrasound technology to measure the functionality of the femoral artery at baseline and again at the one-, two- and three-hour mark. The men were required to sit during a three-hour period, but also walk on a treadmill for five minutes at a speed of 2 mph at the 30-minute mark, 1.5-hour mark, and 2.5-hour mark in the second trial. The researchers used the same method to measure the functionality of the femoral artery at the same intervals as in the other trial.
The findings revealed that during a three-hour period, the flow-mediated dilation, or the expansion of the arteries as a result of increased blood flow of the main artery in the legs, was impaired by as much as 50 percent after just one hour, according to the Indiana University Bloomington Newsroom news release. The participants who walked for five minutes for each hour of sitting saw their arterial function stayed the same, meaning it did not drop throughout the three-hour period. The researchers believe this is due to an increase in muscle activity and blood flow.
"The impairment in endothelial function is significant after just one hour of sitting. It is interesting to see that light physical activity can help in preventing this impairment," Thosar said. Although this small study suggests three five-minute walks can undo the negative effects of sitting, can these results be applied to a larger population? Are periods of short walks or a longer walk more effective?
Dr. Eric R. Saxton, a chiropractor at Saxton Chiropractic and Rehab in Sterling, Va., believes the effect of these walks would be twofold. “Primarily, walking around will increase blood flow and metabolic rate,” he told Medical Daily in an email. He recommends these five-minute walks be taken separately rather than together because they tend to be more effective when spread out. However, for those who are unable to leave their office, Saxton suggests “getting up at least every hour, even if it is just to stand at your desk while talking on the phone.”
His advice is supported by a recent study published in the Mayo Clinic Proceedings, which found going to the gym isn’t likely to reverse the damage caused by sitting all day. Six hours of sitting negated the positive health benefits of exercising for an hour. However, taking a break from sitting by doing moderate exercise or movement can positively impact your health.
So in short, yes, a few five-minute walks around the park can reverse the effects of sitting all day to keep your body powered on.
Bielko SL, Johnston JD, Mather KJ, Thosar SS, Wallace JP. Effect of Prolonged Sitting and Breaks in Sitting Time on Endothelial Function. Medicine & Science in Sports & Exercise. 2014.
Ayers CR, Berry JD, Blair SN et al. Association Between Cardiorespiratory Fitness and Accelerometer-Derived Physical Activity and Sedentary Time in the General Population. Mayo Clinic Proceedings. 2014.