HAMILTON, Ontario – When it comes to working out, some people seem to bulk up with very little effort. For others, they can go to the gym everyday and still see very little muscle gain. The reasons behind these differences in muscle development have been elusive. Now, scientists say a set of 141 genes may control the rate at which people “get pumped up.”
Researchers at McMaster University studied a group of young men (ages 18 to 30) as they completed an eight-week weight training routine. The catch is the group only exercised one leg. Following the exercise experiment, the men then had their non-exercised leg immobilized using a walking boot for two weeks to prevent it from bearing any weight.
“The variation in muscle growth between people makes it very challenging to isolate what drives that growth,” says first author Tanner Stokes in a media release. “Using both legs of the same person to both load and unload muscles allowed us to make a direct comparison.”
If you don’t use muscle, you lose it
The study reveals that weight trainers added on between one and 15 percent in muscle mass in their exercised legs. For the neglected leg, the men saw between a one to 18-percent reduction in muscle. Researchers say muscle loss occurs at a much faster rate than muscle gain, nearly five times faster for all participants.
The Canadian team compared the genetic response of the muscles in the two legs. The results reveal this specific group of 141 genes that factor into muscle growth. In subsequent experiments, they uncover that many of these genes also play a role in protein synthesis.
The researchers say that their findings have significant potential for keeping elderly adults healthy.
“Building and retaining muscle is critical to overall health and quality of life,” explains lead researcher Stuart Phillips. “If we can target those genes with lifestyle and drug therapies, we may be able to help seniors and others vulnerable to muscle loss.”
The study is published in the journal Cell Reports.