Replacing TV time with physical activity tied to better odds for healthy aging
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Key takeaways:
- Each 2-hour increment of television watching per day decreased the odds of healthy aging by 12%.
- Conversely, each 2-hour increase in light activity at work per day increased the odds of healthy aging by 6%.
Watching television significantly decreased the odds of healthy aging, but replacing this time with light, moderate or vigorous activity increased these odds, a study showed.
According to Hongying Shi, PhD, from the from the School of Public Health at Wenzhou Medical University in China, and colleagues, associations between sedentary behavior, light physical activity and healthy aging “are rarely reported.”
Additionally, “exploring the association of sedentary behavior with the health of older adults has become particularly important,” they wrote in JAMA Network Open.
In the cohort study, the researchers assessed correlations between light physical activity at home and work, moderate to vigorous physical activity (MVPA) and sedentary television watching with healthy aging among 45,176 women (mean age, 59 years) from the Nurses’ Health Study.
Healthy aging was defined as reaching the age of 70 years with no major chronic diseases and no impairment in subjective memory, mental health or physical function. Those who did not meet these requirements were defined as usual agers.
After 20 years of follow-up, only 8.6% of women were healthy agers.
The researchers found that each 2-hour increment per day of watching television reduced the odds for healthy aging by 12% (95% CI, 7-17).
In comparison, each 2-hour increase per day of light physical activity at work increased the odds of healthy aging by 6% (95% CI, 3-9), whereas each increase of 1-hour of MVPA per day increased the odds by 14% (95% CI, 11-16).
Shi and colleagues noted that replacing 1 hour of sitting watching television with light physical activity at home (OR = 1.08; 95% CI, 1.05-1.12), light physical activity at work (OR = 1.1; 95% CI, 1.07-1.14) or MVPA (OR = 1.28; 95% CI, 1.23-1.34) were all associated with increased odds of healthy aging.
Additionally, among participants who slept 7 hours or fewer per day, replacing television time with sleep was associated with increased odds of healthy aging.
The researchers highlighted several potential mechanisms behind the associations between sedentary behavior and healthy aging. For example, “prolonged sitting may affect physical function by causing distinctive cellular and molecular responses in the skeletal muscle that impairs its function and mitochondrial activity,” they wrote.
They added that television watching “typically displaces physical activity and thus reduces energy expenditure.”
Shi and colleagues reported that 61% (95% CI, 53-68) of usual agers could become healthy agers if they had:
- fewer than 3 hours of television watching per day;
- at least 3 hours of light physical activity at work per day;
- at least 30 minutes of MVPA per day; and
- no overweight or obesity.
There were some study limitations, according to the researchers. The participants self-reported their behaviors, making them less accurate than objective measurements. Additionally, because the study cohort consisted of nurses, the results may not be generalizable to other populations, the researchers noted.
Still, the findings support past research on links between sedentary behavior and mortality and “provide important evidence that a more meaningful reallocation of time in terms of daily activities could have significant implications for individuals and public health,” they concluded.