Can Riding Up Hills Be Considered Strength Training?

[Eden]

Here's a nice description of lots of activities and how they fit in the continuum
http://www.nof.org/prevention/exercise.htm

I don't think anything that is non-impact has a lot of effect on building bone density - but it all has other benefits including better balance and increased muscle tone, which both help to prevent bone breakage too. So no, cycling up hills, yoga, pilates, pushups and weight lifting do not build bone mass, but all can be useful for your overall health and for preventing the falls that cause fractures. Having strong muscles can help to protect weak bones!