Sedentary Behavior Increases Mortality Risk
Sitting for long hours without breaks increases the risk of death. Sedentary behavior is a health risk because it reduces blood flow and metabolism.
Based on decades-long observations of centenarians, author Dan Buettner (Blue Zones) conjectures that people live longer when they get up and move around after sitting for twenty minutes. Now, a rigorous new study published in the Journal of the American Heart Association (JAHA) has data showing that older women who sat for 11.7 hours or more per day increased their risk of death by 30 percent, regardless of whether they exercised vigorously.
Study co-author Steve Nguyen, Ph.D., M.P.H., a postdoctoral fellow at the University of California San Diego Herbert Wertheim School of Public Health and Human Longevity Science, examined measurements of sitting and daily activity collected from hip devices worn for up to seven days by 6,489 women, aged 63 to 99, who were followed for eight years for mortality outcomes. This data was collected in a study led by Andrea LaCroix, Ph.D., M.P.H., Distinguished Professor at the Herbert Wertheim School of Public Health, as part of a long-term national project known as the Women’s Health Initiative (WHI), which began in 1991 and is ongoing.
Nguyen’s paper is the first to apply a novel and validated machine-learned algorithm called CHAP to examine total sitting time and length of sitting bouts in relation to the risk of death. Sedentary behavior is defined as any waking behavior involving sitting or reclining with low energy expenditure. The CHAP algorithm was developed using machine-learning, a type of artificial intelligence, that enhanced its ability to accurately distinguish between standing and sitting. Fine-tuning “sitting” enabled Nguyen to parse total sitting time and usual sitting bout durations.
Sedentary behavior is a health risk because it reduces muscle contractions, blood flow, and glucose metabolism. When sitting, the blood flow throughout the body slows down, decreasing glucose uptake. Muscles aren’t contracting as much, so anything that requires oxygen consumption to move the muscles diminishes, and the pulse rate is low.
Unfortunately, exercise cannot undo these negative effects. According to the study, whether women participated in low or high amounts of moderate-to-vigorous intensity physical activity, they showed the same heightened risk if they sat for long hours.
