Washington ? Creatine may not be just for young athletes. Older men who took the supplement increased strength in just a week, a study found.

Athletes use creatine to get stronger for competition. But this study indicates the supplement may help older men in such ordinary things as getting out of a chair.

“There was added value for many of the typical activities of daily life,” said researcher William Kraemer of the University of Connecticut. “We were surprised it carried over into daily life activities.”

Creatine helps recharge the energy used in short-burst activities such as sprints or weight lifting. The amino acid is made naturally in the liver and kidneys, and is stored in the muscles. But the body’s creatine stores are limited, and it can use quickly what it has stored.

Creatine also is sold as a supplement and used by athletes from high school to the pro level as a legal alternative to steroids. Side effects, when they occur, are mild. Users sometimes report cramping and some weight gain from water retention as creatine draws more fluid into the muscle. Researchers advise users to drink more water.

There are strong indications creatine works, to a limited extent. Earlier studies have found athletes generally get performance increases of 5 percent to 10 percent with creatine supplements.

But Kraemer and his colleagues say earlier studies also have found that a reduced ability to make creatine comes with age. The researchers wanted to see if supplements would improve strength enough to make life easier for older men.

The scientists studied 18 men with an average age of 65. Some got creatine; the others did not, serving as the comparison group. All the men first were trained in the techniques to be tested, including the ability to rise from a chair without using their arms and to walk heel-to-toe for about 18 feet.

The findings are reported in the journal Medicine and Science in Sports and Exercise.

The men on creatine gained 7 percent to 15 percent in the strength of large muscles of the hip, chest and shoulders, but the comparison group made no such gains. The creatine group also took 6 percent to 9 percent less time to get up from a chair or walk heel-to-toe. The percentage gains in strength were in line with what younger people get, the researchers said.

The results demonstrate the potential value of creatine supplements in older people, Kraemer said. “It shows you the stress of the daily life activities is probably more in the untrained elderly than people expect,” he said.

However, Kraemer stopped short of recommending creatine for older people. Some may not respond to the supplements, he said. And other research has reported potential side effects, notably cramping and water retention. This study showed no harmful effects, but at seven days it could not rule out the possibility that side effects could develop with longer use.

And creatine’s benefits may not help all activities, said training supplements researcher Matthew Vukovich, an assistant professor of health, physical education and recreation at South Dakota State University. For instance, although creatine supplements could help people move, it might not help them open jars. “You don’t see it in handgrip,” said Vukovich, who was not a researcher in the study.

Another scientist, Eric S. Rawson of the University of Massachusetts Medical School, said not enough research has been done on creatine and the elderly to be sure the supplement can help them. “I would encourage them to exercise and follow a healthy diet, and not to think so much about nutrition supplements to increase their exercise capacity,” he said.

Frail older people or those with a disease that weakens muscle might benefit, but studies to test this are still being done, Rawson said.