A recent research study in America has found at the end of a ten year trial with over 700 people, that yoga appears to safely raise bone mineral density in the spine and the femur. The participants followed a set programme of 12 yoga asana daily or at least every other day. The 12 poses were “tree, triangle, warrior II, side-angle, twisted (reverse) triangle, locust, bridge, supine hand-to-foot I, supine hand-to-foot II, straight-legged twist, bent-knee twist and corpse pose. Each pose was held for 30 seconds.” Although the study had some limitations (e.g. there was no control group not doing the yoga), the results lend support to the evidence of yoga’s health benefits.

On the other hand (or leg, rather), I also read recently that a research study in the UK conducted over one year with 30 men aged 65 to 80 yrs old, found that daily hopping on one leg increased the bone density in some parts of the hip on that leg. The participants did five sets of 10 hops, with a 15-second rest between each set, every day. More info on the NHS site. (The research was called Hip Hop!)
Hop to your next yoga class!