(CNN) - Patients suffering from heart failure may benefit from testosterone treatment, according to a new study.
Researchers found that people who took testosterone supplements could exercise longer than those who didn't.
About five million Americans have heart failure and it's a leading cause of hospitalization for people over the age of 65 in the U.S.
Testosterone occurs naturally in both men and women but levels go down with age.
The study appears in the journal Circulation.