Older Americans who watch more TV and exercise less are more likely to have walking disabilities, according to a new study in The Journals of Gerontology: Medical Sciences.
Published on Aug. 30, the study is based on prospective data of self-reported diet, physical activity and sedentary behaviors for over 300,000 people ages 50-71. A baseline questionnaire was completed by participants in 1995-1996, and a follow-up questionnaire, including questions about mobility status, was administered in 2004-2006. Spending less than three hours each week doing physical activity was classified as the lowest level of physical activity; more than seven hours was classified as the highest level. Participants were determined to have a mobility disability if they reported an inability to walk or maintain a normal walking pace of less than two miles per hour.
Researchers found participants who reported the lowest level of physical activity and sat the most — seven hours of daily sitting time or more — were twice as likely to have a mobility disability compared with participants who sat fewer than three hours and reported the highest level of physical activity. The most active participants who sat seven hours or more each day were 11 percent more likely to develop a mobility disability, but there was no relation to excess disability among those who sat fewer than six hours.
Researchers also found that across all levels of physical activity, the risk of developing a mobility disability rose with increasing amounts of TV time. Participants reporting the least amount of physical activity and the most amount of daily TV viewing were three times more likely to have a mobility disability compared with the most active people who watched the least amount of daily TV. Those who reported watching the least amount of TV but also the least physical activity had approximately the same odds of having a mobility disability as participants who spent four to seven hours each week doing physical activity and who reported watching the most TV.
The findings suggest that although sedentary time is a risk factor for disability, higher levels of physical activity can reduce some of the harmful consequences that stem from long periods of sedentary time in older people. Regardless of physical activity level, however, high levels of TV time are strongly associated with higher odds of mobility loss.
Previous studies suggest that the association between sedentary time and the risk of chronic diseases, including mobility loss, may be due to the fact that time spent sitting displaces time spent on lower-intensity physical activity that can improve health. TV viewing time may have a stronger association with mobility loss than sedentary time in part because people might tend to sit for long periods of time while watching TV in the evenings, compared with splitting up the time they spend sitting during the day. As watching TV can be structured around programming and specific periods of time, people might also report their TV viewing time with greater accuracy than separate sedentary time.
“Current U.S. public health recommendations for physical activity have not addressed sedentary time,” the researchers stated. “But our results suggest doing so may be useful for reducing mobility disability.”
For more information, visit https://academic.oup.com/bio-medgerontology/article-abstract/doi/10.1093/gerona/glx122/4056501/The-Joint-Associations-of-Sedentary-Time-andguest
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