I started fell running a year ago and have had no injuries until 3 weeks ago. Terrain at 10 miles changed from soft ground to hard rock and my back and left hip started to ache - 2 miles later I was in agony (not helped by carrying the kids heavy kayak to the beacj and back when I got back). Just about recovered now after complete rest and a trip to the physio. I suspect it's been down to overuse and lack of rest but it got me thinking - is there any "essential" stretching and strengthening exercises I could be doing to help prevent injury?