Well depending on the size of your arena, running full out can be dangerous. A horse can slip in the corners or miss them all together and hit a wall. It sounds to me that your mare is just trying to keep the both of you safe.

I agree. A mare named Daisy in my high school does that too. She'll run full out for me outside of the arena, but as soon as we're inside, she refuses to do it because she knows that she could slip or crash and we'd both get hurt as well as the surrounding horses and riders. It does depend on the size of the arena and the footing of the arena. It sounds to me that your mare knows how to keep you both safe and proper ring etiquette.

Well Ann I have the same problem with my Mare. You should start my just asking for more and more. Also her age might mean something too. My mare just turned 4 and now she knows her "big girl" run. This makes it easier for her to run faster in the arena and with shorter strides and still make the time.

If you have any other Questions i am willing to help! :)

well, make sure you are in a big enough space to run fiirst of all. if you dont, she could slip and fall and injure you both. then, you just have to be persistent. if the horse knows she can get away without doing something for you, it can sudenly become a bad habit of not listening to you. show her that you mean buisness, then everything should go smoothly!