Ok, I was riding my horse in the arena and getting a lesson from my trainer. I was performing an excersise my trainer had given me. He threw a little temper tantrum and my trainer said to work him in a circle and make him move his feet. I started off at a lope and went to turn him. He stumbled and fell on his left side into the fence. I managed to grab the fence while I remained partially still on him. He got up and by the grace of god I remained attached to the fence. He must of partially fell on my L leg but really aside from bruises and a pulled muscle, I am ok. I am really wondering what could have caused him to stumble and fall like that? His feet were a little long and he is extremely long legged. Anyone have any input?