Minor Thoughts from me to you

I've heard, from multiple sources, that weight training can increase bone density and strength. According to Gina Kolata, at The New York Times, that's not actually true.

The answer came a little more than a decade ago when scientists did rigorous studies, asking if weight bearing exercise increased bone density in adults. They used DEXA machines, which measure bone density by hitting bones with X-rays. Those studies failed to find anything more than a minuscule exercise effect — on the order of 1 percent or less, which is too small to be clinically significant. As expected, DEXA found bone loss in people who were bedridden and in astronauts. But there was no evidence that bone was gained when people walked or ran.

Scientists have continued to investigate as tests for bone density grow ever more sensitive. More recently, using new and very expensive machines that scan bone and are able to show its structure at a microscopic scale, they reported a tiny exercise effect in one part of the bone’s architecture known as the trabecula, little branches inside bone that link to each other. The cortical shell — the outer layer of bone — also seems to be slightly thicker with weight bearing exercise. But these are minute changes, noted Dr. Clifford Rosen, a bone researcher at the Maine Medical Research Institute. There is no evidence that they make bone stronger or protect it from osteoporosis, he said.

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