At my gym, there seems to be a new craze of people putting the treadmill to max incline, and walking. If done correctly, it can burn lots of calories and help tone, however EVERYONE I see holds on, and I have to fight the urge to tell them they're doing it wrong!
Holding on takes the weight off the legs and it's barely better than walking flat. They get mega (false) numbers on the calories burnt thing though, then go home and eat them all back.
At the very least I figured I'd share here to stop anyone here making that mistake.