Research debunks bodybuilding myth: Growth-promoting hormones don't stimulate strength

June 14, 2012

New research from scientists at McMaster University reveals exercise-related testosterone and growth hormone do not play an influential role in building muscle after weightlifting, despite conventional wisdom suggesting otherwise.

The findings indicate that who look to manipulate those hormones through are wasting their time.

In two separate studies, published in the Journal of Applied Physiology and the European , researchers found anabolic hormones—long thought to be essential for building a muscular frame—do not influence muscle protein synthesis, the process that leads to bigger muscles.

"A popular mindset for weightlifters is that increased levels of hormones after exercise play a key role in building muscle," explains Daniel West, lead author of both studies and a graduate student in the Department of Kinesiology at McMaster. "That is simply not the case."

In the first study, researchers examined the responses of both male and female participants to intense leg exercise. Despite a 45-fold difference in testosterone increase, men and women were able to make new muscle protein at exactly the same rate.

"Since new muscle proteins eventually add up to muscle growth, this is an important finding," says West.

"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."

In the second study, researchers analyzed the post-exercise hormonal responses of 56 young men, aged 18 to 30, who trained five days a week for 12 weeks in total.

The men experienced gains in muscle mass that ranged from virtually nothing to more than 12 pounds, yet their levels of testosterone and growth after exercise showed no relationship to muscle growth or strength gain.

Surprisingly, the researchers noted that cortisol—considered to have the opposite effect of anabolic hormones because it reduces protein synthesis and breaks down tissue—was related to the gain in muscle mass.

"The idea that you can or should base entire exercise training programs on trying to manipulate testosterone or levels is false," says Stuart Phillips, a professor in the Department of Kinesiology. "There is simply no evidence to support this concept."

Explore further: Proteins used to map the aging process

More information: A copy of study published in the European Journal of Applied Physiology can be found at: www.springerlink.com/content/2 … 751g19l/fulltext.pdf

A copy of the paper published in the Journal of Applied Physiology can be found at: jap.physiology.org/content/112/11/1805

Related Stories

Proteins used to map the aging process

June 19, 2011
Loss of muscle mass is not only associated with disease, such as HIV and cancer, but also with the normal aging process. Anabolic steroids are sometimes used to reverse loss of lean muscle tissue but they can have unwanted ...

Older men with higher testosterone levels lose less muscle mass as they age

October 27, 2011
A recent study accepted for publication in The Endocrine Society's Journal of Clinical Endocrinology & Metabolism (JCEM) found that higher levels of testosterone were associated with reduced loss of lean muscle mass in older ...

Researchers investigate muscle-building effect of protein beverages for athletes

August 18, 2011
Physical activity requires strong, healthy muscles. Fortunately, when people exercise on a regular basis, their muscles experience a continuous cycle of muscle breakdown (during exercise) and compensatory remodeling and growth ...

Building muscle without heavy weights

April 26, 2012
Weight training at a lower intensity but with more repetitions may be as effective for building muscle as lifting heavy weights says a new opinion piece in Applied Physiology, Nutrition, and Metabolism.

Recommended for you

Estrogen discovery could shed new light on fertility problems

December 12, 2017
Estrogen produced in the brain is necessary for ovulation in monkeys, according to researchers at the University of Wisconsin-Madison who have upended the traditional understanding of the hormonal cascade that leads to release ...

3-D printed microfibers could provide structure for artificially grown body parts

December 12, 2017
Much as a frame provides structural support for a house and the chassis provides strength and shape for a car, a team of Penn State engineers believe they have a way to create the structural framework for growing living tissue ...

Time of day affects severity of autoimmune disease

December 12, 2017
Insights into how the body clock and time of day influence immune responses are revealed today in a study published in leading international journal Nature Communications. Understanding the effect of the interplay between ...

Potassium is critical to circadian rhythms in human red blood cells

December 12, 2017
An innovative new study from the University of Surrey and Cambridge's MRC Laboratory of Molecular Biology, published in the prestigious journal Nature Communications, has uncovered the secrets of the circadian rhythms in ...

Team identifies DNA element that may cause rare movement disorder

December 11, 2017
A team of Massachusetts General Hospital (MGH) researchers has identified a specific genetic change that may be the cause of a rare but severe neurological disorder called X-linked dystonia parkinsonism (XDP). Occurring only ...

Protein Daple coordinates single-cell and organ-wide directionality in the inner ear

December 11, 2017
Humans inherited the capacity to hear sounds thanks to structures that evolved millions of years ago. Sensory "hair cells" in the inner ear have the amazing ability to convert sound waves into electrical signals and transmit ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.