Go big or spin fast? Biomechanical deterministic models for snowboard freestyle tricks performed on a trampoline.

In snowboard freestyle, rotation is the key indicator of trick difficulty, encouraging riders to perform tricks with more rotation. In many cases, snowboarders learn and practice tricks using training tools such as trampolins and/or landingbags before they transfer this tricks on-snow. It has not yet been scientifically investigated which movement parameters are primarily responsible for the acquisistion of increasingly difficult cork tricks. Hence, the aim of this study was to investigate the influence of each theoretically defined performance parameter on the amount of rotation using deterministic models for halfpipe and kicker tricks, separated for the direction of rotation, performed on a trampoline with a bounce board. Kinematic motion tracking was used to determine biomechanical performance parameters of 157 corks performed by 15 riders, and random intercept models were used to develop deterministic models. The results show that regardless of the discipline and direction of rotation, angular velocity, take-off velocity and the moment of inertia are key performance indicators to increase the amount of rotation. The coefficient of determination showed a high goodness-of-fit and the standardized estimate was highly significant for all investigated performance parameters. These results are important for coaches and riders to teach and learn new skills.