SATURDAY, Oct. 18 (HealthDayNews) -- Lifting weights and other kinds of strength training help older adults fight the loss of muscle mass and strength, and the resulting physical disability and frailty.

But it's not clear whether strength training helps keep older adults healthier and alive longer, says a study in a recent issue of the American Journal of Preventive Medicine.

A Tufts University researcher reviewed 17 studies about strength training in older adults and found some definite blessings.

"The benefits of strength training include increased muscle and bone mass, muscle strength, flexibility, dynamic balance, self-confidence and self-esteem," says Miriam E. Nelson, Friedman School of Nutrition Science and Policy at Tufts, says in a prepared statement.

"Strength training also helps reduce the symptoms of various chronic diseases such as arthritis, depression, type 2 diabetes, osteoporosis, sleep disorders and heart disease and, when combined with balance training, reduces falls," Nelson says.

But her study says there's no clear evidence on whether the benefits of strength training can actually delay the onset of disability, or on how such training helps avert chronic diseases or their symptoms in older adults.

She also notes questions remain about appropriate frequency and intensity of strength training for older adults. The American College of Sports Medicine recommends two to three days a week of strength training, a schedule that Nelson says is appropriate for the elderly.

"The key challenges as this field of exercise science moves forward are to best identify the most appropriate strength-training recommendations for older adults and to greatly increase the access to safe and effective programs in a variety of settings," Nelson says.

More information

Here's where you can learn more about exercise for seniors.