Enhancing assessment of intensive change of direction: minimal models for pelvis movements during approach and exit phases.

This study presents a minimum instrumentation methodology to assist sports biomechanics and coaching teams in improving the performance of individual athletes during the change of direction (COD) manoeuvre. A procedure is introduced to identify the deceleration and re-acceleration phases and evaluate the athlete's control velocity and stability maintenance. This is achieved by adopting a minimal limit cycle model to study sacrum kinematics. The methodology raises the coach's understanding of the athlete deficiencies and gain insight into how the nonlinearity of the pelvis movement could be considered a measure of skill level.