'Too much sitting may cause health risks'

Sitting for too long without taking a break may increase a wide range of health risks, even if one engages in recommended amounts of physical activity, scientists say.

Further studies are needed to determine "the most effective and practical interventions for reducing habitual sitting," said Linda Eanes from the University of Texas Rio Grande Valley in the US.

"Nurses have a pivotal role to play in increasing public awareness about the potential adverse effects of high-volume and prolonged uninterrupted sitting," Eanes said.

In recent years, studies have shown a direct relationship between prolonged sitting and the risk of several chronic health conditions.

Increased health risks have been reported both for high-volume sitting, such as sitting for seven or more hours per day, and for prolonged uninterrupted sitting, such as sitting for 30 minutes or longer without a break.

The health risks of prolonged sitting are independent of whether the person participates in recommended physical activity, according to the study published in the American Journal of Nursing.

Eanes summarised pivotal studies showing the association between high-volume and prolonged uninterrupted sitting and health risks including cardiovascular disease, diabetes, and all-cause mortality.

In conjunction with obesity, sedentary time is also linked to an increased risk of certain cancers, including ovarian, endometrial, and colon cancer.

Immobility decreases stimulation of weight-bearing muscles, leading to decreased activity of an enzyme (lipoprotein lipase) that plays an essential role in lipid metabolism, including production of "good" cholesterol as well as uptake of glucose from the blood.

In contrast, breaking up sedentary times with frequent bouts of standing or slow walking may reduce these metabolic risks -- although the optimal levels of standing or walking remain unclear, researchers said.

Nurses and other healthcare professionals now have a new priority: educating patients about the health risks of prolonged sedentary time and making suggestions to reduce and interrupt sitting times.

Proposed interventions include using a standing desk or taking frequent walking or standing breaks, as well as the use of computer or smartphone reminders to take brief physical activity breaks during the day.

In contrast to efforts to increase physical activity, merely providing people with information and education might be effective in promoting reduction of sedentary behaviour, researchers said.

"Nurses can also actively encourage all patients, regardless of demographics, to balance sedentary behaviour and physical activity simply by taking more frequent standing or walking breaks," Eanes writes.