In a large international study, researchers at Uppsala University have identified DNA regions that are associated with physical activity or leisure screen time. The findings confirm that physical activity is beneficial for health and suggest that a more sedentary lifestyle can be explained by how muscles respond to exercise.

 

It is well established that a physically active lifestyle and less time spent sitting are associated with better health. However, trends over time suggest that people in higher income countries are becoming increasingly less active. It is also known from twin and family studies that genetic factors influence physical activity levels, but the biological basis for why some people are more physically active than others remains poorly understood.

 

To improve our understanding of mechanisms that influence physical activity and its role in disease prevention, researchers from Uppsala University, together with researchers from around the world, combined genetic data from over 700,000 individuals participating in 51 research studies. In doing so, they identified 99 DNA regions that are associated with how much time people report spending on moderate-to-vigorous intensity physical activity or watching a screen during their leisure time.

 

The researchers used DNA variants as instrumental variables and showed that less screen time lowers the risk of obesity. Less screen time and more time spent in moderate-to-vigorous intensity physical activity also protect from diabetes, attention deficit hyperactivity disorder, depression, and earlier age at death.

 

"We confirmed that physical activity has beneficial effects on health outcomes. We also found that all outcomes that we examined are driven by physical activity's beneficial effect on body mass," says Zhe Wang from Icahn School of Medicine at Mount Sinai in New York and first author of the paper.

 

Further analyses showed that DNA variants associated with leisure screen time are more often located close to genes whose activity in skeletal muscle is changed by strength training. This suggests that these genes may influence the likelihood of adopting an active lifestyle by affecting the response to training.