With trails and parks snowed over, what do people think about supplementing winter training with a treadmill in order to try and stay off the roads (say 1/2-3/4 on the roads and the rest on a treadmill)? I searched the boards about the topic and it was hard to find conclusive answers. Are there any real downsides in terms of running form or running efficiency. I'm not too concerned about the pace conversions because most of the mill runs will be easy stuff and I can handle the boredom. I'm more concerned about the physical negatives (I saw weakening of hamstrings / quads, is this true?) thanks alot