Hi, the easiest method is to compile say all the track records for all tracks over all distances then compute the the intersect an slope of distance an time using regression formula, then this will provide you with the rate of deceleration of track record holders as they progress up in distance, for tracks that have two turns as oppossed to one tracks you would use the centripedatal formula which makes allowance for the loss of speed negotiating the turns.
Cheers