500m Bareback flatout gallop on Horse

me and my 14 2 hh brumby mare, doing a 500m sprint being clocked by the car, it was amazing she held a speed of 62km, h and was still going at an even pace after 500m and it still felt like she had more to give, i wasn t going to ask her for it though as we ran out of straight track and i needed time to stop, for such a small horse my girl has amazing stamina and enduance, and when we pulled up she wasn t even breathing heavy, and no shes not 100 fit but thats just her born to run, its her fav activity, and