Androgens Alone Do Not Increase Muscle Quality
Androgens Alone Do Not Increase Muscle Quality
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Men who take supplemental androgens-the male hormone testosterone or similar medications-increase their strength by adding muscle mass, but androgens alone do not pack more might into the muscles, according to studies presented today by University of Southern California researchers.
Treatment with androgens increases lean body mass - which encompasses everything in the body except bone and fat - and strength increases proportionately with the amount of muscle added, says E. Todd Schroeder, at the Keck School of Medicine of USC. Schroeder presented his findings at the Endocrine Society's 85th Annual Meeting.
However, when men use androgen therapy combined with resistance training, such as weightlifting, their gains in strength may far outpace the amount of muscle that can be added with androgens alone. Each muscle cell packs a bigger punch, a concept known as improved muscle quality.
"The results of androgen therapy alone on muscle and strength are not necessarily bad, but they are not optimal," Schroeder says. "The men did improve their strength, but it was proportional to the muscle mass they added."
The findings wield health implications beyond the stereotypes of muscle-bound bodybuilders. Schroeder and his colleagues are studying the usefulness of androgens and exercise in helping maintain muscle strength, muscle power and physical function among seniors, for example. They also have studied androgen therapy's effectiveness in battling wasting among HIV-positive patients.
In their study, Schroeder and colleagues Michael Terk and Fred R. Sattler, looked at both young men and seniors. They followed two groups: 33 seniors ranging from their mid-60s to late 70s, and 23 HIV-positive men ranging from their early 30s to late 40s.
The younger men were randomly assigned to get 600 milligrams (mg) each week of nandrolone alone or in combination with resistance training. The older men were randomly assigned to receive 20 mg a day of oxandrolone or a placebo. These pharmacologic androgen doses were given over 12 weeks.
Researchers determined maximal strength-the most weight a participant could safely lift or push-using leg press, leg extension and leg flexion machines.
The researchers also measured the cross-sectional area of participants' thighs and the lean body mass of their lower extremities by magnetic resonance imaging, or MRI. They then determined the strength that participants exerted for each unit of muscle (muscle quality) and how muscle quality changed over time.
Androgens alone increased lean body mass and maximum strength in both groups of men, but "gains were modest," Schroeder says, and muscle quality did not change, since the muscle size and strength both increased proportionately. However, among those using nandrolone and undergoing resistance training, muscle quality improved significantly: Gains in strength were much greater than the gains that could occur from muscle-mass increase alone.
"It is clear from our studies and others that resistance training is critical for increasing muscle quality, but the effects can probably be augmented with androgens," Schroeder says. "In addition, not everyone can do resistance training, and a short course of androgens can help get people stronger and more functional."
Finally, results provide researchers insight into how to better design future studies to test strategies to best preserve and even improve muscle strength and physical function among seniors. Similar studies will be important for other types of patients who experience muscle loss and frailty, such as those with cancer, chronic lung disease, chronic renal failure and other conditions.
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