The finding comes from four small studies of people with heart failure. The studies included nearly 200 patients, mostly men around 67-years old.
About half the patients received testosterone by injection, patch or gel for as little as three months or as long as one year. The other half got a placebo.
Researchers concluded those who took testosterone supplements were able to exercise longer than those who did not.
The study appears in the journal Circulation.
Doctors say larger and longer studies are needed to prove the treatment is safe and effective for heart failure patients.
