"There is no downside to physical activity." This is what the moderator, an MD, of the session at which the results of a study showing increased bone mass and bone size in 7 and 8 year olds who performed "intensive physical exercise." "The concern was that if you over-exercise young prepubertal individuals, you might actually increase the risk of fracture."
You have got to be kidding me! The medical profession never ceases to amaze me in their hesitancy to embrace good lifestyle habits. WOW!
Jack LaLanne has it right... just get up and get moving!