Scientists in Sweden have made looks to be a significant breakthrough in the quest to establish exactly how exercise leads to better health and fitness.

It’s an accepted principle that exercise helps us attain better levels of fitness and reduce the risk of many cardiovascular diseases, but the biology behind this has long remained unclear. Now, researchers at the Karolinska Institute in Stockholm believe they may have cracked the case, concluding that regular exercise has the power to actually change the shape and functioning of our genes by altering our DNA.

“Through endurance training — a lifestyle change that is easily available for most people and doesn’t cost much money,” the study’s lead researcher, Malene Lindholm, told The New York Times, “we can induce changes that affect how we use our genes and, through that, get healthier and more functional muscles that ultimately improve our quality of life.”

The study recruited 23 young and healthy men and women and placed them on a three month cycling programme whereby they only pedalled with one of their legs. With the relevant muscle metrics measured before and after the programme, the non-pedalling leg served as the control for each participant, showing how their genes would be affected by normal life without exercise.

As you might expect, after the three months, there were clear physical improvements evident in the exercised leg that were not present in the idle leg. Scientists were then able to home in on the changes that had taken place at cell level.

By using cutting edge genomic analysis, the researchers found that exercise has the ability to change the methylation patterns on the genome of muscle cells, altering the proteins these genes express. This in turn affects the physiological responses elsewhere in the body. A large majority of these genes play a role in energy metabolism, insulin response and inflammation within muscles – regulating how fit these muscles – and in turn our bodies – can become.

Lindholm says that now the focus should turn to whether these genetic changes would remain if someone was to stop exercising, as well as the impacts different types of training have on our genes. The scientist and her colleagues hope explore these areas in further studies.

To view the full study – An integrative analysis reveals coordinated reprogramming of the epigenome and the transcriptome in human skeletal muscle after training – click here.