NEW YORK (Reuters Health) - Running, jumping and other high impact activities during childhood benefits bone health by increasing the size and strength of the growing skeleton, suggests new research. Moreover, the benefits in bone size and strength induced by exercise during growth persist lifelong -- even if exercise is ceased.

"The lifelong maintenance of exercise benefits gained during growth may help reduce an individual's risk of osteoporotic fracture as they age," said study chief Dr. Stuart J. Warden, director of research in physical therapy at the Indiana University School of Health and Rehabilitation Sciences in Indianapolis.

For their study, Warden's team exercised the right, but not the left, forearms of young growing rats for a few minutes three times per week for seven weeks. They analyzed the amount and structure of bone in the rats' right and left forearms before and after exercise, according to the report, published in the Journal of Bone and Mineral Research.

"The exercise resulted in an increase in the size and strength of the exercised bones," Warden told Reuters Health.

Following seven weeks of exercise, the rats did no exercise for another 92 weeks -- virtually their entire lifespan. "Despite not being exercised during aging, all of the benefits gained by exercise during growth remained throughout the animals' lifespan," Warden said.

The "take home" messages are straight forward, he said. "Children should be encouraged to undertake regular exercise during growth to enhance their lifelong bone health."

Exercises that appear beneficial to the growing skeleton include weight bearing activities that involve some form of impact loading, such as jumping and landing, like basketball and jump rope, Warden noted.

Although, exercise during growth appears particularly important, "continuing to exercise throughout the lifespan is highly recommended as it can help maintain skeletal benefits of exercise, as well as maintain balance and fitness, all of which aid in reducing the risk of osteoporotic fractures as an individual ages," he emphasized.