The researchers from Uppsala University investigated the mechanisms that influence physical activity and its role in disease prevention through combining genetic data of over 700,000 people. As a result, 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.

Next, 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.

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.

In total, the researchers identified 46 genes in the 99 DNA regions that could be relevant for linking genetics and physical activity. The findings suggest that pathways related to locomotion and muscle weakness due to dysfunction of the muscle fibre are probably involved.