In December last year I pulled a ham string and boy was it painful! It was nearly 3 months before I could walk properly again! I've managed to do a couple of long hikes since with no problems, but I have been extremely nervous about starting to off road run again.
I decided last Sunday that enough was enough, so I took a tentative run, thinking that after so long I would find it difficult to get in the rhythm again. I decided to carefully run, walk, run, walk, run walk short distances (about 100yds at a time) to test myself out. I tried this for a mile, I then felt so good, I lost personal discipline and ran the next two miles without stopping. I was most surprised how easy it was!
I've since run every day since and so far no problems at all.
I used each run to test out my base layers, I have a merino, a bamboo and a synthetic. Interestingly, the most comfortable when sweating is the bamboo top, easy on the skin and even when damp with perspiration still so comfortable to wear. When I'm hiking I prefer the synthetic.