The Influence Of Second-Row Players On Lumbar Spine Kinematics Of Front-Row Players During Rugby Union Scrummaging

Objectives. - In rugby union scrummaging, front-row players often sustain lumbar spine injuries, which can lead to physical impairments and absence from play. Poor lumbar spine posture adopted by front-row players during scrummaging may contribute to these lumbar spine injuries. However, few studies have investigated lumbar spine kinematics in front-row players during scrummaging and therefore little is known about what factors influence lumbar spine posture. The focus of this study was to determine whether interactions with other players affect front-row players' ability to adopt and/or maintain a neutral lumbar spine posture.Equipment and methods. - Lumbar spine kinematics were investigated in 15 front-row players during scrums under two conditions: (i) one-man scrums, and (ii) scrums with the support of two second-row players. Lumbar spine three-dimensional kinematics were obtained using a system of five digital single-lens reflex cameras and photogrammetric software package. A Bayesian approach was used to determine the effect of scrummaging conditions.Results. - The results showed that players adopt neutral posture when scrummaging alone. In contrast, when supported by second-row players, participants adopted a flexed posture (kyphosis), which may contribute to lumbar spine injuries. However, the supported scrum condition did not change lateral-flexion (0 degrees to 2 degrees) and axial rotation (0 degrees to 2 degrees) of the spine substantially. These results suggest that training and rehabilitation programs should focus on practicing a neutral posture during scrums involving second-row players to minimise spinal stress. (C) 2020 Elsevier Masson SAS. All rights reserved.