I used to run with an ankle support and a pair of Walsh fell boots which together provide some reasonable degree of support after some pretty nasty ankle sprains. one particularly memorable sprain was done on Caw in the duddon valley and I had to run\hobble back over the fells to the 3 shires stone. Not my brightest idea.I think in my case the wearing of a support and slight subconcious adaptation to my running style has brought chronic injury problems over time. My advice (which I probably would have ignored myself 2 years ago) would be to really invest time in rehabilitating your strength, proprioception and muscle recruitment before you go near the fells again.support or not. I think they also restrict your natural ankle movement to a degree.