Public release date: 14-Jun-2012 [ | E-mail | Share ]

Contact: Michelle Donovan donovam@mcmaster.ca 905-525-9104 McMaster University

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 bodybuilders who look to manipulate those hormones through exercise routines are wasting their time.

In two separate studies, published in the Journal of Applied Physiology and the European Journal of Applied Physiology, researchers found anabolic hormoneslong thought to be essential for building a muscular framedo 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.

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