In a new study, researchers examined why some weightlifters’ muscles grow much more quickly than others’.
They found genes that cause some people to gain muscle while others don’t.
The research was conducted by a team from McMaster University and elsewhere.
In the study, the team did a novel experiment in which a group of young men worked out one leg and immobilized the other over 10 weeks.
Throughout the experiment, participants built up muscle in one of their legs through a prescribed regime of weight training.
For the first eight weeks of the study, the opposite leg served as a non-exercising control.
For the last two weeks, the non-exercising leg was immobilized entirely with a brace to keep it from bearing weight.
The team found in just two weeks, the immobilized leg, on average, lost the same amount of muscle mass the opposite leg had gained through more than two months of weight training.
In other words, the average person lost muscle through inactivity at about five times the rate he had gained it through weightlifting.
Comparing the genetic responses of the muscles in the two legs helped the team more precisely isolate what drives exercise-related muscle growth, generating new knowledge in the fight against debilitating muscle loss in older people.
The key appears to lie in a set of 141 genes that regulate the growth of the body’s skeletal muscles. Tethered to the skeleton by tendons, they are the muscles that control power and movement.
The team says the variation in muscle growth between people makes it very challenging to isolate what drives that growth.
The findings can be particularly useful for helping to keep seniors healthy and safe. Building and retaining muscle is critical to overall health and quality of life.
If scientists can target those genes with lifestyle and drug therapies, they may be able to help seniors and others vulnerable to muscle loss.
One author of the study is Stuart Phillips, a professor of Kinesiology.
The study is published in Cell Reports.
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