Sitting for more than 25 minutes: study finds muscles become markedly less active

People who sit for long stretches without a break appear to use their muscles far less, according to a team at Australia's Swinburne University led by Christian Brakenridge. The scientists fitted 84 adults with shorts whose conductive fabric records electrical activity in the thigh muscles. In total they analyzed 7,684 sitting periods, Men's Journal reported. The study was published in late September and presented by the university on Oct. 12; the outlet Shafaqna named the journal as npj Exercise Medicine and Health.

According to the findings, muscle activity declined the longer participants sat, approaching its lowest measurable level. People who typically sat for at least 25 minutes at a time had less active muscles while seated than those who broke up their sitting more often. Longer and more vigorous movement before sitting down was linked to more muscle activity afterward. “We use our muscles less when sitting for a prolonged time,” Brakenridge said. Even in participants who appeared motionless, the sensors picked up small muscle contractions.

According to Men's Journal, lower muscle activity may affect circulation and blood sugar regulation; the outlet Shafaqna links it to a possibly higher risk of heart disease and type 2 diabetes. However, the study did not establish that 25 minutes of sitting causes disease, Men's Journal noted. The authors estimated that more frequent, more vigorous breaks could add about five minutes of muscle activity per hour of sitting. Shafaqna describes so-called active sitting, such as driving or working at a desk, as less harmful than long, passive sitting.