High-impact activities that stress the bones may be good for you, new research shows.
According a
New York Times report, researchers at the University of Bristol have found teens who participated in bone-jarring exercise had notably sturdier hip bones than those who did not.
Past experiments have found that subjecting bones to abrupt stress prompts them to add mass or at least reduces their loss of mass as people age. What has been in dispute, however, is how much force is needed to be beneficial.
The Bristol researchers tracked male and female adolescents — for whom bone mass expands rapidly — in their daily routines. The bone density of their hips was also measured.
After a week, the scientists checked each teenager's exposure to G forces — a measure of impact — and found those who experienced impacts of 4.2 Gs or greater had sturdier hipbones. They noted running a 10-minute mile or jumping up onto and down from a box at least 15 inches high was needed can produce forces that great.
The bottom line: People should probably run pretty fast or jump high to generate forces great enough to help build bone.
But follow-up experiments by the same researchers found few adults are doing so. The follow-up involved 20 women older than 60 who were outfitted with activity monitors as they ran through an aerobics class, several brisk walks, and a session of stepping onto and off a foot-high box. None of the women reached the 4-G threshold .
Lead researcher Jon Tobias, M.D., a professor of rheumatology at the University of Bristol, said while impacts that produce fewer than 4 Gs of force may help adults maintain bone mass, it is unclear what level of force below 4 Gs is needed.
So, Dr. Tobias suggested, young people and healthy adults should probably pound the ground.
He added: "I plan to keep running until my joints wear out."