I was out for a run over the brecon beacons horseshoe with extra ascent by coming up from pont yr daf car park. The weather was fair, with good visibility and ground conditions with minimal wind. The day had started out with a chill so I had warm kit on from the car. As the day warmed up and I drank my water, in the last few miles (second ascent up to pen y fan from cribyn), I started suffering from dehydration. On the descent, down the path from pen y fan to pont yr daf, I lost concentration and fell over at speed. I went head over heels and rolled over my shoulders back on to my feet. I came away with light cuts and grazes. However, I had pulled my shoulder and done some soft tissue damage which I occasionally still have issues with 3 months later.