According to a study by researchers from Karolinska Institute which was published in the journal PLOS Genetics, endurance training changes the activity of thousands of genes and gives rise to a multitude of altered DNA-copies and RNA. The study also nuances the concept of muscle memory.
How regular endurance works on a molecular level is not fully known but it is however known that it can be used to prevent cardiovascular disease, diabetes, obesity and other such conditions.
RNA, the molecular copies of the DNA-sequence in muscle tissue before and after endurance training has now been analyzed by the researchers at Karolinska Institute. The researchers found approximately 3,400 RNA variants which were associated with 2,600 genes that changed in response to training. A significance of the study is that training can incite the same gene to increase the production of one RNA variant and reduce that of another. According to the researchers, this can mean that genes can change function as a result of exercise and, for example, start to promote the production of certain protein variants over others.
“It has not been previously shown that training changes the expression of genes in this particular way. The study also provides new basic information about how the body adapts to regular endurance training and what role many of our genes play in the adaptation,” says Dr Maléne Lindholm at Karolinska Institute’s Department of Physiology and Pharmacology.
The study commenced with an exercise program that involved working only one leg and for 23 individuals. Samples of the muscles were taken before and after the training period. The participants then exercised both legs in the same way as in the first period of exercise, with muscle samples taken from both legs after a rest period of nine months.
“We were looking for any residual effects of previous training, a kind of muscle memory as it were, and trying to find out if this could influence the response to repeated training,” Said Dr Maléne Lindholm.
When the participants resumed training, the changed genetic activity in the previously trained leg was no longer present. The repeated response to training was however different in the trained and previously untrained legs in the second training period, which suggests that the exercise could have left other lasting impacts.
The study according to Dr Lindholm is important, above all, for the fundamental understanding of how muscles operate and how we take up endurance training.
“The results can also contribute to the future optimization of training effects in different individuals,” she says. “In the long run, it is conceivably of some significance to the possibility of preventing cardiovascular disease and the development of new, more precise drugs for people who, for whatever reason, are unable to exercise.”