Injuries to the triceps surae muscle of elite rugby union front rowers: A 3 dimensional kinematic analysis of the front row during live scrimmaging

Introduction: The increasing incidence of injury to the triceps surae muscle in high performance front row rugby union (rugby) players has stimulated a need to investigate the events surrounding this injury. Previous research has linked triceps surae muscle injuries with both scrummaging and activities which mimic those of scrummaging, but possible mechanisms of injury remain uninvestigated. In addition, limited published data exists that has reported the biomechanics of scrum technique in high performance players. Of these studies the majority have been undertaken using scrummaging machines, with research on the biomechanics of live scrummaging even less well documented. Accordingly, the purpose of this study was to investigate the lower limb kinematics during a series of scrummaging drills. It was hypothesized that analysing the biomechanics of this aspect of game play would provide greater understanding of the possible causes and mechanisms for triceps surae injury.Methodology: Eleven high performance front row rugby players were landmarked for 16 anatomical points and then videoed during a series of 2-on-1 (attacking) and 1 -on-2 (defensive) live scrummaging drills using four digital camcorders (Panasonic NV-GS180GN) operating at 50 Hz. On completion of data collection, the 16 land marked anatomical points were digitised for each frame using APAS motion analysis software and a three-dimensional model of the trunk and lower limb developed. A series of one way ANOVA were used to determine if the spatio temporal descriptors of the lower limb kinematics differed between defensive and attacking scrummaging technique. All statistical analyses were performed using SPSS for Windows (version 17). A significance level of P less than 0.05 was used for all analysis.Results/conclusions: Results (presented as mean ± SD) showed numerous significant differences in a range of spatio temporal variables between defensive and attacking scrum types. Analysis indicated a clear trend towards more extended positions in the defensive scrum drills. For example, relative ankle angular displacement from foot strike to toe-off varied significantly (P less than 0.05) between the attacking (−13° [±7]) and defensive scrum drills (3° [±8]), as did relative ankle angular displacement at peak extension velocity between the attacking (108 deg [±12]) and defensive scrum drills (97° [±9]) during single leg stance. It was concluded that these more extended joint positions contribute to increased triceps surae load during attacking scrummaging activity. This study also showed that the scrummaging techniques of the subjects had the potential to predispose them to triceps surae injury