July 1 (HealthDay News) -- Elderly men who exercised and received the growth hormone known as "mechano growth factor" (MGF) showed increased muscle mass, according to a British study.

The results suggest that MGF may help treat age-related loss of muscle strength, which causes increased fragility, said Dr. Geoff Goldspink of the Royal Free and University College Medical School, who presented the study findings July 1 at the annual meeting of the Society of Experimental Biology in Glasgow, Scotland.

The growth hormone may also benefit patients who can't do intensive exercise because of diseases such as muscular dystrophy, amyotrophic lateral sclerosis (ALS), kidney disease or cancer. MGF may even help slow muscle loss among astronauts who spend long hours in zero gravity during space travel.

MGF, which is produced naturally when muscles are stretched during exercise, activates stem cells already present in muscle tissue, Goldspink explained. Once activated, the stem cells begin to divide and create additional muscle fibers that increase the size and strength of the muscle.

Levels of MGF decline as people age. This, combined with a lack of intense physical activity, may cause muscle wasting in the elderly. While treatment with MGF may prove beneficial in such cases, the downside "is that MGF has great potential for doping in sports," Goldspink added.

"A synthetic version is already available over the Internet, and although it is very expensive, it is expected that new technologies will bring down the price to make it comparable to that of human insulin," he said.

SOURCE: Society for Experimental Biology, news release, July 1, 2009