Supplements made with the male hormone testosterone helped heart failure patients breathe better and exercise more often, according to a new analysis of studies in the journal Circulation Heart Failure.
The analysis examined four studies that tested the effectiveness of testosterone patches, gels and injections in patients with moderate to severe chronic heart failure.
Based on the analysis, patients receiving testosterone performed significantly better in tests of exercise endurance than those not taking supplements. Two of the studies also showed the severity of heart failure improved in 35 percent of treated patients compared to less than 10 percent of those who didn't receive the supplements.
Researchers said gains in muscle and skeletal endurance appeared quickly and lasted for a least one year.
"The improvement in exercise capacity was consistent across all of the studies," said researcher Dr. Justin A. Ezekowitz, director of the Heart Function Clinic at the University of Alberta in Edmonton. "Compared to patients in placebo groups, the differences were striking."
The studies involved nearly 200 patients, averaging 67 years of age. No significant negative effects were reported.
Larger studies are now needed to confirm the findings, Ezekowitz said. "We don't want patients and their loved ones rushing to buy testosterone supplements online, or physicians to misinterpret the findings. First the results need to be corroborated in large clinical trials."