I mean, for example - good barrel racers tend to be downhill and have very powerful hindquarters. Jumpers tend to be uphill and have longer legs.
Here is a list of every discipline I could think of, feel free to add any I missed. Just add to the sport you have the best experience in, or know the most about.
Cowboy Mounted Shooting
Driving (any sub-catagory of it)
Halter (this one can be a very broad subject)