First, stretch before and
after practice! Stretch in between your exercises and during breaks. Also, don't sit down during practice after hard exercise. Walk until your heart returns to normal, just you would a horse. It'll keep your muscles from freezing up. Warm up and cool down slowly. Once you get home, take some Motrin. It does miracles.
Take a warm bath and massage your legs.
I do track as well (discus thrower, primarily). I feel your pain. This time of year is tough, but it'll get easier once you get stronger. You use different muscles for riding then you do track running.