How Much Exercise Is Too Much Exercise When It Comes To Your Bones?

culled from:.prevention.com

The numbers are grim: More than half of American adults over 50 have low bone mineral density, putting them at increased risk for fractures. Now for the good news: this bone loss can be reversed with regular exercise—and the more exercise you get, the stronger your bones will be, finds new research from the University of Texas School of Public Health.
Scientists have known that exercising, say 30 minutes a day, five days a week can help protect bones. However, some past research suggested that too much exercise might be bad for your bones.
Hoping to end the confusion, researchers in this new study checked bone mineral density in more than 12,000 adults, concentrating on the hips and lumbar spine—two of the most common spots for fractures—and also asked participants how much exercise they got in a typical week. 

After separating the study participants into groups based on their physical activity levels—those who got the recommended 150 minutes, those who doubled them, tripled them, and so on—Whitfield discovered that any amount of exercise would strengthen bones. "Even women who perform 6 times the recommended amount of exercise—which adds up to more than 2 hours a day—weren't at risk for low bone mineral density," says study author Geoffrey P. Whitfield, PhD. 
Every step you take seems to help: Compared to completely sedentary women, those who got any exercise at all had about a 1% increase in bone mineral density in their hips. "That may not sound like a lot, but there's evidence that even very small changes in bone mineral density can have a very significant impact on fracture risk," says Whitfield. 
Although Whitfield didn't ask participants what kind of workouts they were doing, he says "anything that involves contact with the ground" will help. "Walking, jogging, hiking—those are the activities that stimulate bone growth." And don't forget about strength training: Weights and bands will build your bones, as well.