Experts suggest 20 to 30 minutes of resistance exercises two to three times a week. [Photo provided to China Daily]

People turning 50 may want to consider tweaking their exercise routines because they face stiffer joints, slower recovery from injury and the loss of lean body mass among other perils as they age, fitness experts say.

Studies have shown that even a 90-year-old can build muscle, so the half-century mark is a good time to retire joint-stressing high jumps and to start lifting dumbbells to build strength.

Wayne Westcott, co-author of the book Strength Training Past 50, says maintaining lean body mass becomes harder with aging.

"The averageman in good shape is about 85 percent lean weight, organs, blood, bones, muscles and skin, to 15 percent fat. The average healthy woman has a 75/25 ratio," says Westcott, fitness research director at the South Shore YMCA in Quincy, Massachusetts.

"It's more challenging with age but if you do strength training you can maintain your lean muscle to about age 70, "he says, adding that an older woman who does no resistance training will lose up to 4.5 kg of lean mass per decade.

Westcott places equal value on cardiovascular training.

"We recommend approximately 20 to 30 minutes of resistance exercises two to three times a week. Then try to have an equal amount of aerobic activity four to five days a week," he explains.