high-impact exercise;good for bones
bones should be jarred for their own good. experiments have definitively established that subjecting bones to abrupt stress prompts them to add mass or at least reduces their loss of mass as people age.
researchers at the University of Bristol gathered male and female adolescents and found that the body accumulates bone mass rapidly at this time of life. they had them go about their daily lives with activity monitors. A week later, the scientists reclaimed the monitors to check each teenager’s exposure to G forces, a measure of impact. Those who experienced impacts of 4.2 G’s or greater — though these were infrequent — had notably sturdier hipbones. it was also found that if you jump off of 15 feet boxes or run a mile or even sprint your hip bone mass could be greatly increased .