Researchers from Norway and Australia have found that it takes an hour or more of moderate intensity physical activity every day to eliminate the increased risk of death associated with prolonged sitting time. That’s about 3 times the recommended daily amount of physical activity. The American Cancer Society recommends adults get at least 150 minutes of moderate intensity or 75 minutes of vigorous intensity activity each week. But most Americans don’t get that much.
The researchers looked at data from more than 1 million people in 16 studies, including the records of people enrolled in the American Cancer Society Cancer Prevention Study II Nutrition Cohort. They grouped people into 4 categories, depending on how much physical activity they reported. The least active group reported getting less than 5 minutes of physical activity every day. The next group said they were active for about 25-35 minutes each day, the next group for about 50-65 minutes each day, and the most active group said they got about 60-75 minutes of activity each day. Examples of physical activity included brisk walking, or bicycling at 10 miles an hour.
The study was published July 27, 2016 in The Lancet. The analysis confirmed that people who sat for the longest periods of time and were the least active increased their risk of death the most.
People who sat for 8 hours a day but were physically active had a lower risk of death than those who sat for fewer hours a day but were not physically active. It took at least an hour of daily activity to eliminate the risks of sitting for 8 hours a day, but the study showed that shorter amounts of activity also helped. For example, those in the 25-35 minute group had a lower risk than the inactive group.
Alpa Patel, PhD, American Cancer Society Strategic Director, Cancer Prevention Study 3, said, “If you are not active, the single most important thing you can do for your health is to go from doing nothing to doing something.”
Patel says all adults should work toward reaching the minimum level of physical activity recommended by the American Cancer Society, and then work toward increasing the level of activity from moderate to vigorous. Moderate-intensity activities are those at the level of a brisk walk. Vigorous-intensity activities increase your heart rate and breathing, and make you sweat. Examples include running, aerobic dance, and soccer.
Patel says some studies also indicate there are health benefits to breaking up long periods of sitting. She suggests looking for ways to naturally incorporate movement into your work day:
The research team also looked specifically at time spent watching TV as a subset of sitting time. They found that watching TV for more than 3 hours per day was linked to an increased risk of death in all activity groups except the most active group. They also found that the increased risk of death from sitting and watching TV was even greater than the increased risk of death from total sitting time in general.
The authors speculate that watching TV may be associated with other unhealthy behaviors such as snacking or less physical activity. Patel also says it’s more likely that people report TV watching time more accurately than they do other periods of sitting time.
To reduce sitting time while watching TV, try doing a few simple exercises or stretches while you watch. Or make a new rule: no sitting down during commercials.
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Citation: Does physical activity attenuate, or even eliminate, the detrimental association of sitting time with mortality? A harmonised meta-analysis of data from more than 1 million men and women. Published July 27, 2016 in The Lancet. First author Ulf Ekelund, PhD, Norwegian School of Sport Sciences, Oslo, Norway.