A biomechanical approach to evaluating field sports performance using a model-based image-matching technique: A case report of 4 defensive football game situations

Defensive actions are considered to be of major importance for success in football games, yet the biomechanical aspects of defensive actions remain unknown. Providing information on movements from real game situations is crucial, as players can learn how to improve their performance. The main purpose of this case study was to evaluate the feasibility of a Model-based Image-matching (MBIM) technique to quantitatively analyse one-on-one defensive movement in real football game situations. Two of the 4 defenders studied performed side-step manoeuvres (side-1, -2) whereas the other 2 used cross-over-step manoeuvres (crossover-1, -2). Side-1 and crossover-1 were considered successful because the players were able to stop the attacker during the dribble. On the other hand, the side-2 and crossover-2 cases were considered unsuccessful because the players were not able to stop the dribble attack. Model-matching was successful in all situations and revealed that compared with the unsuccessful defenders, the 2 successful defenders performed cutting manoeuvres with shorter ground contact time, smaller centre of mass displacement, and lesser knee and hip flexion. It therefore seems feasible to use this technique in further studies with a larger number of players to study defensive performance in football. Moreover, we propose that the MBIM method and lab studies on field sports assessment should be combined to produce much better results as compared with the visual inspection approach.