Study author Dr. Justin A. Ezekowitz, an assistant professor and director of the Heart Function Clinic at the University of Alberta in Edmonton, and colleagues analyzed four randomized clinical trials of patients with moderate to severe chronic heart failure.
The analysis involved 198 patients -- 84 percent men, average age 67 -- were given commercial testosterone supplements by injection, patch or gel. One study involved only women.
The study, published in Circulation Heart Failure, found those who received supplemental testosterone scored 50 percent better than those receiving placebo in a 6-minute walking test, and the researchers noted gains in muscle and skeletal endurance that appeared quickly and lasted for a least one year. Those involved in the study involving only women were given lower doses of testosterone than men in the other trials received, but similar improvements were found.
"The improvement in exercise capacity was consistent across all of the studies," Ezekowitz said in a statement. "Compared to patients in placebo groups, the differences were striking."
None of the male patients developed signs of prostate disease and there was no increase in cardiovascular events, Ezekowitz said.