If you sit a lot, take short walking breaks at least every hour. This may lessen or even prevent some of the adverse effects that prolonged sitting can have on the cardiovascular system, according to a small study published in September 2014 in Medicine & Science in Sports & Exercise.
Many studies have linked prolonged sitting to increased risk of heart disease, stroke, diabetes, and other chronic conditions, even in people who exercise regularly. Part of the reason may be that sitting impairs endothelial function—the ability of blood vessels to expand and contract.
When healthy young men sat for three hours without moving their legs, endothelial function (as measured in the main leg artery) dropped significantly beginning in the first hour. But when they broke up their sitting time with slow 5-minute walks—every 30 or 60 minutes—there was no decline in function.