Originally Posted by Mike ODonnell
I'd be curious to know also, as it was my assumption that osteoporosis needed weight bearing activity to stimulate the osteoblasts (bone building) cells.
weight bearing is a big part of it, but you'll also see osteoblast activity near tendon insertions that are under tension. so any kind of resisted movement is better than nothing. which is how most of these studies go... swimming is better than lying in bed. but does that mean swimming is the best, or even a good, activity for preventing/treating osteoporosis? not necessarily. the fact alone that there is no loaded eccentric portion of movement in a pool means that you're giving away half the potential resistance against the muscle and therefore bone strengthening potential.
the only time i would suggest swimming as the best option is if the person is presently super compromised and is a fall risk . in that case, i'd consider swimming as a wise first stage. once they improve some from that, then you get them back into dry land and on their feet so they can get the best adaptations.