Elderly, frail men experience benefits from testosterone treatment, such as increased strength, but the improvements disappear within six months once the therapy is halted, according to a new study.

"Whatever benefit that you might accrue from testosterone in the short term is not maintained beyond the period of treatment," said study researcher Dr. Frederick Wu, of the University of Manchester in the U.K.

As men grow older, they lose muscle mass and strength, which can lead to frailty and physical limitations. Testosterone levels naturally decrease with age, and low levels may contribute to some of this muscle deterioration, the researchers said. If frail men have to cut back on their physical activity, their muscles may experience even more loss of mass, leading to a vicious cycle of decreased activity and muscle decline.

Scientists had suspected a temporary boost in testosterone levels may break this cycle, leading to long-term benefits without the need for ongoing treatments, according to the researchers. Taking testosterone for prolonged periods may have adverse side effects for older men, including an increased risk of heart attacks , or stimulating the growth of prostate cancer if it is already present.

In the study, 274 frail men between the ages of 65 and 90 with low testosterone levels were given either testosterone therapy or a placebo for six months. Men given testosterone saw an increase in their muscle bulk and muscle strength , and improvements in their quality of life.

But six months later, their testosterone levels had returned to what they were before the study, and all the benefits previously seen with therapy had disappeared.

The participants received relatively low doses of testosterone compared to those given in other studies, and it's possible that higher doses may lead to even bigger physical improvements that would confer sustained benefits, the researchers said.

In order to break the cycle of muscle deterioration, a combination of therapies may be best, the researchers said.

"There are many different approaches to try to improve frailty, using hormones is just one of them," Wu told MyHealthNewsDaily. "You might need to consider more than one modality of treatment to manage people who are frail," he said.

Future studies involving more people need to be conducted before researchers can determine whether testosterone therapy is an effective, safe treatment for frail men, Wu said.

The study was will be published in the February 2011 issue of the Journal of Clinical Endocrinology & Metabolism.