The Kipping Trainer

Kipping is a technique used in CrossFit that allows an athlete to build momentum while hanging from a bar. The motion of kipping involves moving from an arch position to a hollow body position. This movement is driven from the athlete’s shoulders and hips. Kipping helps an athlete to perform multiple pull ups, chest to bars, toes to bars, or bar muscle-ups without fatigue. The better an athlete is at kipping, the better the athlete will perform in a workout.

This paper uses a dynamic three-link model to simulate the motion of an athlete performing kipping. The links consist of the arms, trunk, and legs of the athlete. The joints consist of the grip to the bar, the shoulders, the hips and the feet of the athlete. Using desired positions of these joints, we are able to simulate a desired arch trajectory. We can then calculate the torque values over time starting from a neutral position where the only force acting on the system is gravity (the athlete dead hanging from the bar). This gives us three torque values changing during the duration of the motion.