Especially if they are going to be inverted. When in Park City, members of the U.S. snowboard team train at Black Diamond gymnastics, which allows snowboarders to practice aerials, with their boards, on trampolines. If these riders are going to be upside down a lot, they'd better get used to the feeling. Otherwise they'll be trying it out on snow. Which can end up down your pants, in your gloves and in your ears.
Simple lunges affect the hamstrings, glutes and quadriceps.
From a standing position, step forward, leaving the trailing foot in the same place. The front foot should be equal to the length of your arm span. When in the lunging position, push your hips straight down until your knee is bent 90 degrees from the ground. Push back up with your forward foot to the standing position. Repeat 15 times on each side three times.