The analysis revealed slight gains in bone mass of 1-2 percent, for those who exercised hardest and showed the greatest increases in aerobic fitness, muscle strength and muscle tissue.

The Hopkins study is believed to be the first to evaluate the effects of exercise independently from other factors, primarily diet, on bone mineral density, a strong gauge of bone health, against the risk of osteoporosis and bone fracture. Indeed, the researchers believe that more intense exercise may demonstrate significantly increased bone mass.

"Older people are very concerned about how best to reduce their body fat as a means of preventing other health problems, such as heart disease and diabetes,” says lead study investigator and exercise physiologist Kerry Stewart, Ed.D., director of clinical exercise physiology and heart health programs at Johns Hopkins. "However, excess fat does have the benefit of maintaining bone mass. But fat loss through diet alone can lead to loss of bone, worsening the body's natural bone loss due to aging, a major risk factor for bone fractures.”

For a six-month period, the Hopkins team assessed the benefits of a supervised program of exercise training in a group of 104 older men and women, measuring both fitness and fatness levels at the start and end of the study. Half were randomly placed in a widely recommended moderate exercise program, believed to improve fitness, heart health and body composition, while the rest maintained their usual physical routine and diet.

In both men and women who exercised and lost weight, overall bone density did not change, although results were mixed for women in specific sites of the hip. However, those who showed the greatest gains in fitness had modest gains in bone density at several sites, and loss of body fat was not associated with bone loss.

MEDICA.de; Source: Johns Hopkins Medical Institutions