[Lyikmcmb]

I would advise against only treadmill running. A treadmill creates the same stresses on the same parts of your legs because the surface is flat and uniform. Running outside results in running on all sorts of different surfaces at different angles and such that it distributes the stress to other parts of your legs and helps a little to lessen the stress of running. I personally prefer running outside since it is more interesting. 30 minutes running outside feels like 15 minutes or so. 30 minutes on a treadmill feels like an hour. I hate treadmills...