Is it normal that i shart during a race if i don't poop before hand?

Okay, so indoor track season is coming up, but I have a major concern. Last year during my first track meet I had to run the 300m race. It's a straight out sprint the whole time and is a very difficult race. Since it was my first race of the year I wasn't really In incredible shape for long sprints like this one. It's a two lap race around my track and after my first lap I was beginning to give up, but I pushed myself so hard to finish that I was sick the next day. Also the day after, my butt felt very uncomfortable. I went to the bathroom to see what it was and it was that I sharted myself during the race and I didn't even realize it and I went through half of school with dried up shit on my ass. I almost threw up and was extremely ashamed in myself for such a childish mistake. The next week, the same thing happened again, but I knew I sharted as soon as the race was over. I tried to figure it out and it was that I needed to poop before a race or else the same thing would happen. Sure it was a pain in the ass to deal with, but it's a year later and I hope my body can keep my poop in. Also no one else knew that I sharted. It was all secret. My question is though, is that normal to happen if I run my butt off so hard that I will shart? Or do I might have some disorder?