Australian researchers believe they have discovered a way to hold back frailty in old age.
The research, carried out at Sydney's Garvan Institute, shows small doses of testosterone delivered directly to the liver could prevent the muscle wasting associated with ageing and many chronic diseases.
Weakening of the body is seen as an inevitable part of ageing and has major public health implications.
Endocrinologist Professor Ken Ho says the scale of dysfunction that arises as a result of muscle wasting is now preventable.
"Ageing is a very, very complex process but one of the consequences of ageing is frailty and frailty arises from a loss of muscle mass," he explained.
"It is my view that if our invention or discovery achieves what we predict it to do, then it would be a substantial contribution to this aspect of public health."
The findings, published in the European Journal of Endocrinology, show pure crystalline testosterone, taken orally, went straight to the liver without spilling into to the bloodstream and other organs.
Benefits of testosterone therapy can be outweighed by the side effects. Too much can poison the liver, damage heart muscles and cause aggression and unwanted hair growth.
The researchers believe this new approach allows people to benefit from testosterone while sidestepping the negative side effects.
"Our invention is really quite simple," Professor Ho said. "The novel aspect of this research is that only the liver gets tickled with testosterone.
"It is a new way of using an old hormone."
The liver then metabolises the testosterone so that none of this hormone spills into the peripheral circulation.
And as a result of that, all body tissues and organs apart from the liver do not get exposed to the hormone.
Professor Ho says this method stimulated protein synthesis at about the same level achieved by other, more risky methods.
He said a small study on post-menopausal women has proved the concept.
Now a larger study is needed to investigate the long term effect of oral testosterone on muscle mass and function.
The benefits could be enormous for a wide range of people, including patients with chronic kidney diseases.
Reducing muscle wasting in frail elderly people could also prevent falls and reduce osteoporotic fractures.