Citation

Cazzola D, Preatoni E, Stokes K, England M, Trewartha G. Br. J. Sports Med. 2014; 48(7): 578.

Affiliation

University of Bath, Bath, United Kingdom.

Copyright

(Copyright © 2014, BMJ Publishing Group)

DOI

10.1136/bjsports-2014-093494.49

PMID

24620090

Abstract

BACKGROUND: The Rugby Union scrum has evolved into a highly dynamic activity, particularly during engagement. Although catastrophic spinal injuries in rugby are extremely rare, approximately 40% of these are associated with the scrum. Repeated scrum engagement may also contribute to premature chronic degeneration of the cervical spine in rugby players. OBJECTIVE: To compare the biomechanical stresses experienced by rugby forward players during live contested scrummaging under different scrum engagement processes, taking into account different playing standards. DESIGN: A cross-sectional design, where teams from five different playing levels performed live scrums under three engagement processes: 1) CTPE (Crouch-Touch-Pause-Engage, 2011-2012); 2) CTS (Crouch-Touch-Set, 2012-2013); and 3) PreBind (Crouch-Bind-Set, 2013-2014). Measures were made via body-worn sensors and video analysis. SETTING: Outdoors, natural turf rugby pitches. PARTICIPANTS: 27 rugby teams (i.e. 54 forward packs, n=432 players) from five playing levels - International, Elite, Community, Women and University. RISK FACTOR ASSESSMENT: The three engagement processes. PreBind differs from CTS/CTPE with a legal bind that is taken at the "Bind" call and maintained through the "Set" action. MAIN OUTCOME MEASUREMENTS: Biomechanical stresses (force, acceleration) and kinematics (engagement speed, joints angles) characterising the scrum motion. RESULTS: The PreBind process reduced biomechanical stresses by 15-25% with respect to both CTPE and CTS during the engagement phase without reducing force during the sustained push phase. For front row players, peak cervical acceleration was reduced from 8.2 g (CTPE) and 7.9 g (CTS) to 6.8 g (PreBind), and peak compression forces decreased from 8.4 kN (CTPE) and 8.3 kN (CTS) to 6.3 kN (PreBind). Players' movements/postures did not differ significantly between engagement processes. The mixed design ANOVA did not evidence any significant interaction effect (engagement type-playing level) in any variable. CONCLUSIONS: The PreBind process reduced the mechanical stresses on front row players and may lead to safer conditions without affecting performance.

Language: en