High testosterone levels in men may protect against loss of muscle mass as they age, a new study says.

Men over age 65 in the study who had higher testosterone levels lost less of their lean muscle mass over the four-year study, especially in their arms and legs, than men who had lower testosterone levels.

In addition, men with higher testosterone levels lost less leg function, and could stand up more easily from a chair.

"The amount of testosterone men have in their bodies may contribute to how much muscle and strength they lose as they get older," said study researcher Dr. Erin LeBlanc, of Kaiser Permanente Northwest in Portland. "Our study adds evidence to the growing body of literature that suggest higher levels of endogenous testosterone may be favorably associated with some key components of healthy aging in men," LeBlanc said.

Loss of muscle mass and strength contribute to frailty and are associated with falls, mobility limitations and fractures. Men lose more muscle mass and strength than women as they age, suggesting that sex steroids, and testosterone in particular, may contribute to body composition and physical function changes, according to the study.

The new study included 1,183 participants; researchers measured the amounts of muscle and fat in their bodies using dual energy X-ray absorptiometry (DXA) scans. Physical performance was measured using a series of exercises that assessed grip strength, lower extremity power, walking speed and the ability to rise from a chair without using its arms.

The study will be published in the December issue of the Journal of Clinical Endocrinology & Metabolism.

Pass it on: Higher testosterone levels may protect against muscle mass loss in men.