you need to be able run in a variety of conditions, in this country a race may be held in 25C heat, the next year the same race at the same time of year may be windy, raining and is nearly freezing. Eight miles also shows any chafing issues particular in raining conditions.
enough said, you went to the gym but next time go out and get use to rain
suffered from AT for the past two years or so, I think that I have finally got rid of it. Physio and insoles, researched the internet for insoles and found silly prices but bought some from Lidl and it seems to have worked. No pain whilst running and can walk the following morning rather than hobbling about for five minutes.