Study: 2D qualitative movement assessment of a deceleration
The deceleration (pressing) is a common situational pattern leading to anterior cruciate ligament (ACL) injury in football. The aim of the present study was to describe a 2D scoring system for the assessment of the deceleration task and to associate it with the knee joint loading (knee abduction moment) evaluated through the gold standard 3D motion capture. The hypothesis was that lower 2D scores would be associated with higher knee joint loading.

34 competitive football players performed a series of deceleration tasks. 3D motion analysis was recorded using ten stereophotogrammetric cameras, a force platform, and three high-speed cameras. The 2D qualitative assessment was performed via a scoring system based on the video analysis of frontal and lateral planes joint kinematics for five scoring criteria.

--An ICC more than 0.94 was found for all the 2D scoring criteria, both for intra-rater and inter-rater reliability.

--The players with low 2D frontal plane scores and low total scores (0–4) showed significantly higher peak knee abduction moment values.

--A significant negative rank correlation was found between the total score and the peak knee abduction moment.

Finally, during a deceleration exercise, the qualitative 2D scoring system described correctly distinguished between athletes with high and low knee joint loads. The use of this qualitative movement evaluation based on a detailed and accurate scoring system is appropriate for identifying players and patients with high knee joint loading and directing extra training in the context of reducing the risk of primary and subsequent ACL injury.