Prolonged sitting is potentially damaging to the arteries but a new study published in Medicine & Science in Sports & Exercise, the official journal of the American College of Sports Medicine, reveals that it can be easily reversed with hourly 5-minute walks.

Sitting for long periods of time is associated with risk factors such as higher cholesterol levels and greater waist circumference that can lead to cardiovascular and metabolic disease. When people sit, slack muscles do not contract to effectively pump blood to the heart. Blood can pool in the legs and affect the endothelial function of arteries, or the ability of blood vessels to expand from increased blood flow.

The research involved 11 non-obese, healthy men between the ages of 20-35 who participated in two randomised trials. In one trial, they sat for three hours without moving their legs. Researchers used a blood pressure cuff and ultrasound technology to measure how each of the femoral arteries functioned when the men first sat down, and again at the one, two and three-hour mark.

In the second experiment, the men again sat for 3 hours, but also walked on a treadmill set at a speed of 2 mph for 5 minutes at the 30-minute, 1.5-hour and 2.5-hour marks. Again, the researchers measured how well the femoral arteries of the participants were functioning.

The researchers found that, while sitting, the dilation and expansion of the participants' arteries were impaired by up to 50% after just the first hour.

However, there was no decrease in arterial function among the participants who walked for 5 minutes each hour. The researchers think this is because the increase in muscle activity aided blood flow.

Lead study author Saurabh Thosar, a postdoctoral researcher at Oregon Health & Science University in Portland, US, said:

"There is plenty of epidemiological evidence linking sitting time to various chronic diseases and linking breaking sitting time to beneficial cardiovascular effects, but there is very little experimental evidence. We have shown that prolonged sitting impairs endothelial function, which is an early marker of cardiovascular disease, and that breaking sitting time prevents the decline in that function."