What’s the best cross training for runners?
I do think LaRue is right that there will be variability across individuals training in the same discipline, and that each person will have somewhat different needs.
Buy I also agree with Jocelyn that yoga can be good for some runners. in fact I have members of runners groups in some of my classes. The stretching, particularly around the calfs and hips and legs is part of what is useful, but there are other things the discipline has to offer. This is a blog post I did recently on the subject, if you would be interested:
http://blog.ideafit.com/blogs/ariadne-greenberg/yoga-for-runners