An exercise plan that focuses on increasing levels of growth hormones and testosterone may not help you gain more muscle strength, says new research.
It is commonly believed that these exercise-related growth hormones help in muscle building, but two new studies now say that this is not true.
"A popular mindset for weightlifters is that increased levels of hormones after exercise play a key role in building muscle. That is simply not the case," said Daniel West, a graduate student in the Department of Kinesiology at McMaster. West is a lead author of the studies.
Unexpectedly, cortisol was found to be associated with muscle gain. Cortisol is considered to be just the opposite of growth hormones as it reduces protein synthesis in the body.
"Since new muscle proteins eventually add up to muscle growth, this is an important finding," says West.
In the first study, researchers analyzed how men and women respond to intense exercises. The exercises did increase the levels of testosterone in the body but it did not have any effect on the muscle growth.
The studies were based on hormones that are naturally produced in the body. Researchers say that hormone supplements do lead to muscle gain.
"While testosterone is definitely anabolic and promotes muscle growth in men and women at high doses, such as those used during steroid abuse, our findings show that naturally occurring levels of testosterone do not influence the rate of muscle protein synthesis," West said, in a university press release.
In the second study, some 56 men were recruited. They had to exercise for five times a week for 12 weeks. They gained a considerable amount of muscle mass at the end of the session but the increase wasn't associated with the levels of growth hormones.
"The idea that you can or should base entire exercise training programs on trying to manipulate testosterone or growth hormone levels is false. There is simply no evidence to support this concept," said Stuart Phillips, a professor in the Department of Kinesiology at McMaster University.