In a comprehensive global study, scientists from Uppsala University found DNA regions associated with physical activity or leisure screen use. The findings indicate that a more sedentary lifestyle may be explained by how muscles adapt to training and demonstrate the health advantages of physical activity.
The study’s results were released in the Nature Genetics publication. It is commonly known that living an active lifestyle and spending less time sitting down are linked to greater health. People in better income nations appear to be growing less active, nevertheless, according to patterns across time.
The genetic reason for why some people are more physically active than others is also known from twin and family studies, although the scientific underpinnings of this phenomenon are still poorly understood.
Researchers from Uppsala University integrated genetic information from more than 700,000 participants in 51 research projects in order to better understand the processes that affect physical exercise and its function in illness prevention. They did this in order to identify 99 DNA areas that are connected to the amount of time people report spending engaging in moderate-to-vigorous physical activity or watching a screen in their free time.
“We know that people tend to overreport how much time they spend on physical activity, but around half of the DNA regions we identified also show robust associations with physical activity as measured using devices that people wore during daily life. This adds further credibility to our findings,” says Ruth Loos from the Novo Nordisk Foundation Center for Basic Metabolic Research, at the University of Copenhagen.
The researchers then demonstrated that decreased screen time decreases the risk of obesity using DNA variations as instrumental factors. Less screen time and more time engaged in moderate-to-vigorous physical exercise also lower the risk of developing diabetes, ADHD, depression, and an earlier mortality age.
“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.
Additional research revealed that DNA polymorphisms linked to screen time during leisure are more frequently found among genes whose activity in skeletal muscle is altered by strength training. This shows that by changing the reaction to exercise, these genes may affect the chance of pursuing an active lifestyle.
More in-depth study on one gene led to the discovery of a DNA variation that alters a protein building block found only in fast-twitch skeletal muscle fibres.
“Our results show that this change results in more elastic muscle fibres that can deliver less force, but are likely less susceptible to exercise-induced muscle damage. We think that this reduced risk of muscle damage after exercise makes it easier for people to have a more active lifestyle,” says co-author Andrew Emmerich from the Department of Cell and Molecular Biology, Uppsala University.
Genes that may lead to less physical activity
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.
“We cannot currently claim that these 46 genes cause someone to be more or less physically active in daily life, but they provide great leads for further studies. Perhaps in the future it will even be possible to trigger the beneficial effects of physical activity without the need to be physically active,” says Marcel den Hoed, researcher at the Department of Immunology, Genetics and Pathology at Uppsala University, and lead author of the paper.