Originally Posted by ajax

Oh, yes. I agree. I've been a runner for 15+ years and took about the past six months off due to a strange knee condition - did the cross-trainer instead for the duration and there's almost no comparison. Although the impact on the joints is far less, the training benefits are somewhere between 2/3 and 3/4 of what you'd get on a treadmill - which means isntead of running 40 minutes, you have to spend an hour on the cross-trainer.