Testosterone ups older men's muscle performance

NEW YORK, 18 july 2009-- A testosterone patch, particularly in combination with a growth hormone injection, improves body composition and muscle performance in older men, according to a new study.

Elderly men often see a decline in the levels of such two hormones, and in previous studies, when researchers boosted levels to those found in men's youth, muscle strength and other characteristics improved.

However, it has been "unclear whether these benefits translate to enhanced functional performance," Dr. Fred R. Sattler, of University of Southern California, Los Angeles, and colleagues note in their report in the Journal of Clinical Endocrinology and Metabolism.

Sattler and colleagues studied 122 men with an average age of about 71 years. They report their findings in the Journal of Clinical Endocrinology and Metabolism.

All had levels of the growth hormone -- known as insulin-like growth factor-1 -- and testosterone typical of men their age. They received either a 5-gram testosterone patch per day, a 10-gram testosterone patch per day, alone or alone or along with three different daily doses of a standard growth hormone injection. That broke them into six different groups.

Across the six groups, following 16 weeks of treatment, there was an average increase of 1-3 kilograms (2.2-6.6 pounds) in lean body mass. The highest gain, of 7.5 kg (16.5 lbs), was seen in the highest testosterone and growth hormone dose group.

Total fat mass decreased by 0.4 to 2.3 kilograms (0.9-5.1 pounds) and fat in the torso was reduced by as much as 1.5 kilograms (4.9 pounds). Aerobic endurance increased by an average of 96 seconds, and one measure of muscle strength -- composite maximum voluntary strength of upper and lower body muscles -- rose by 14 percent to 35 percent.

The changes when the two treatments were combined "were of greater magnitude than treatment with testosterone alone," Sattler told Reuters Health.

There were some side effects, including increased blood pressure and aching and muscle pain.

Despite the gains, Dr. Sattler cautioned that the treatments required further study, particularly to test their effects on prostate and heart health.

SOURCE: Journal of Clinical Endocrinology and Metabolism, June 2009.