Weight training is one of the weapons to fight osteoporosis

TUCSON, Arizona (CNN) -- Researchers at the University of Arizona are looking for new ways to increase bone density in women. Early results show that combining strength training with hormone-replacement therapy and calcium supplements helps to strengthen bones.

"Our exercise training program is a rigorous resistance program with weight-bearing aerobic activity combined with exercises for strength and balance," said researcher Linda Houtkooper.

Study participant Mary Ornelia, 60, said she knows she is at risk of developing osteoporosis.

"I was having hip pain and went for x-rays and all of this," she said. "And now for two and a half years, I haven't been bothered at all."

She was one of more than 300 post-menopausal women who have been following the weight training routine for three years -- lifting weights, doing weight-resistance exercise and even wearing weighted vests -- to put stress on the muscles and tissue that are attached to the bone.

"There is some theory that it is not how much weight you expect the bone to be able to carry or resist, or how fast or slow you put that resistance to the bone, but doing them in different ways," Houtkooper said. "The terminology is if you can surprise the bone in the way you load it, that may be a way to continue to stimulate more bone mineralization and bone strengthening."

Taking the hormone estrogen may also help osteoporosis by increasing calcium absorption by the bones.

The research also shows adding vigorous strength training plus 800 milligrams of calcium daily can protect and even replenish bone mineral and hopefully, prevent bone fractures as people age.

"A woman's chance of getting a fracture in the hip is equal to her chance of combined risk of breast cancer, uterine cancer and ovarian cancer," said University of Arizona researcher Timothy Lohman.

Those fractures cost at least $10 billion each year in medical care and could climb to $62 billion 20 years from now, doubling again in another two decades.