In developed nations, adults spend an average of 9-10 hours every day sitting, mostly during work hours. A highly sedentary lifestyle is associated with an increased risk of mortality. The World Health Organization (WHO) recommends 150-300 minutes of moderate to vigorous physical activity per week or at least 75 minutes of vigorous exercise, or a combination of both.
This study found 22 minutes of daily moderate to vigorous physical activity can reduce risk of dying prematurely as a result of a sedentary lifestyle. The beneficial effects of exercise were dose-dependent, so the more exercise, the greater a reduction in mortality risk, up to a point.
This study tracked 11,989 individuals who participated in several fitness-tracker-based studies: the Norwegian Tromso Study, the Swedish Healthy Aging Initiative, the Norwegian National Physical Activity Survey, and the U.S. National Health and Nutrition Examination Survey.
All participants were 50 years or older. Additional data included weight, height, sex, education level, alcohol use, smoking, and any incidence of previous cancer, cardiovascular disease, or diabetes.
A total of 5,943 participants spent less than 10.5 hours sitting every day, while 6,042 participants sat for 10.5 or more hours daily. For those exercising less than 22 minutes a day, sitting for more than 12 hours was associated with a 38% increased risk of mortality compared to sitting for 8 hours.
While a higher amount of moderate to vigorous physical activity was associated with a lower risk of death, irrespective of the amount of sedentary time, the association between sedentary time and mortality was largely influenced by the amount of moderate to vigorous physical activity. For example, an extra 10 minutes a day of moderate to vigorous physical activity was associated with a 15% lower mortality risk in those spending fewer than 10.5 sedentary hours, and a 35% lower risk among those spending more than 10.5 sedentary hours. Light intensity physical activity was only associated with a lower mortality risk among highly sedentary individuals (12+ daily hours).
The authors concluded efforts to promote physical activity may have substantial health benefits, and small amounts of moderate to vigorous physical activity may be an effective strategy to ameliorate mortality risk associated with high sedentary time.
