Treadmills are the machines runners love to hate. Most of us would prefer the fresh air and sense of adventure that goes along with getting outside, to running in place on a moving belt. And yet on days when the road conditions are dangerous and it's just too cold to be outside, the treadmill is the only way to get in a workout. It is a saving for which we are profusely grateful. After all, when forced to choose between the monotony of the mill and risking a fall-induced injury on slick roads that could sideline you until spring, it’s an easy decision.