Researchers in the U.S. say they believe an experimental drug designed to kick-start growth hormones in humans may also be of advantage in the aging process.
The drug Capromorelin produced by drug manufacturer Pfizer appears to help people age without the frailty many suffer.
Experts predict that by 2010 more than 40 million people will be over age 60 in the United States and not all of them will be particularly fit.
Scientists have always questioned why some people manage to age quite successfully and live to very old ages with relatively little impairment, while others do not.
Capromorelin is a growth hormone stimulator which causes the body to secrete a human growth hormone in the way seen at puberty and in young adulthood.
Growth hormone is vital in childhood growth, and production of the hormone peaks during puberty but it continues to affect physical function throughout our lives, and it regulates metabolism and body composition.
In young adults, those spurts of the growth hormone are associated with a buildup of lean muscle mass and strength, while elderly people have much lower levels of the hormone and less lean muscle mass.
Many of the effects of aging - increased abdominal fat, reduced muscle mass, and decreased physical function - look very similar to the symptoms of growth hormone deficiency in younger people.
As those aging take effect, many older adults find it difficult to care for themselves, and they lose quality of life and are often forced to resort to long-term care.
Dr. George Merriam and colleagues of the University of Washington tested Capromorelin on 395 men and women aged between 65 and 84.
All were in some way frail and had suffered falls or lost grip strength and their walking ability had slowed down.
They were divided into groups which either received a placebo or one of four different levels of Capromorelin.
The researchers measured the participants' fat and lean body mass (muscle), as well as their performance in physical tests such as stair climbing and a heel-to-toe walk.
They also received blood tests to measure levels of growth hormones.
The treatment resulted in improved physical function over the 6 to 12 month study period with higher levels of growth hormone in the bloodstream.
There were some minor side effects which included increased fatigue, insomnia, and fasting glucose levels.
Patients who got the drug gained an average of 3 pounds (1.4 kg) in lean muscle mass after six months, and were more able to walk a straight line which is a test of balance, strength and coordination.
Dr. Merriam says a year later, they also showed an improvement in stair climbing.
However Dr. Merriam says though the drug promises an improvement in physical function enabling older people to continue to live independently, acquiring a license to produce and market such a therapy would be difficult, as the Food and Drug Administration does not consider aging to be a disease.
At present Capromorelin is only available for research purposes, not as a prescription or over-the-counter drug.
The report was presented to a meeting of the International Congress of Neuroendocrinology.