Based on extensive observations of centenarians, author Dan Buettner, renowned for his work on Blue Zones, proposes that longevity is bolstered by regular movement, such as standing up every twenty minutes after sitting. This theory is now substantiated by compelling new research published in the Journal of the American Heart Association (JAHA). The study reveals that older women who spend more than 11.7 hours a day sitting escalate their mortality risk by a staggering 30%, irrespective of their levels of vigorous exercise. These findings underscore the critical role of sedentary behaviour in health and longevity.
The study, co-authored by Steve Nguyen, PhD, M.P.H., a postdoctoral fellow at the University of California San Diego’s Herbert Wertheim School of Public Health and Human Longevity Science, utilised data from a larger project, the Women’s Health Initiative (WHI), which began in 1991. This particular analysis involved 6,489 women aged between 63 and 99 who were monitored over eight years for mortality outcomes. The data included detailed measurements from hip-worn devices tracking sitting and daily activity over up to seven days.
Nguyen’s research is groundbreaking as it introduces a sophisticated, machine-learned algorithm named CHAP to assess total sitting time and the length of sitting bouts in relation to mortality risk. Unlike previous methods, which relied on simple movement thresholds, CHAP uses machine learning to more accurately differentiate between sitting and standing. This innovative approach has allowed Nguyen to refine the definitions and measurements of “sitting”, capturing both the total time spent seated and the typical duration of these periods. This novel method paves the way for more precise and comprehensive studies on the impact of sedentary behaviour on health.
The health implications of sedentary behaviour are significant, primarily because it inhibits muscle contractions, reduces blood flow, and decreases glucose metabolism. According to Andrea LaCroix, PhD, M.P.H., the Distinguished Professor at the Herbert Wertheim School, sitting leads to slowed blood circulation, diminished glucose uptake, reduced muscle activity, and a lower heart rate. These physiological changes highlight why sedentary lifestyles are problematic, regardless of exercise levels.
LaCroix points out that occasional exercise cannot counteract the hours spent sitting. She notes that even an hour of brisk walking is insufficient if the rest of the day is spent seated, as the negative impacts on metabolism persist. She recommends reducing the risk by limiting sitting to less than 11 hours daily and avoiding prolonged uninterrupted sitting. Even by standing briefly every 20 minutes, breaking up long sitting periods can mitigate some risks.
Nguyen, however, acknowledges that not all forms of sitting are equally detrimental. He considers the cognitive engagement involved in certain sedentary activities, such as studying a new language, which might have different implications for health. The complexity of determining the overall impact of sedentary behaviour on conditions such as dementia is an area Nguyen is exploring further, supported by a National Institute of General Medical Sciences K99 award.
LaCroix understands the challenge of altering sedentary habits in a world captivated by engaging but stationary activities like watching TV or browsing social media. Yet, she believes that cultural shifts away from prolonged sitting could significantly enhance our health, aligning more closely with our evolutionary design for movement. This optimistic view suggests that with awareness and concerted efforts, we can make significant strides towards a healthier, more active lifestyle. This blend of historical insight, contemporary research, and technological innovation in measuring physical activity provides a nuanced understanding of the profound effects our lifestyle choices have on longevity and health, and offers a beacon of hope for a healthier future.
More information: Steve Nguyen et al, Prospective Associations of Accelerometer‐Measured Machine‐Learned Sedentary Behavior With Death Among Older Women: The OPACH Study, Journal of the American Heart Association. DOI: 10.1161/JAHA.123.031156
Journal information: Journal of the American Heart Association Provided by University of California San Diego
