Rugby Tackle Height: head-down and low tackle height increase the cervical spine injury risk

Dario Cazzola, Pavlos Silvestros

Research output: Chapter or section in a book/report/conference proceedingChapter in a published conference proceeding

2 Downloads (Pure)

Abstract

Rugby tackling is a fundamental defensive movement used in open play to stop the opposition gaining territory, and unfortunately carries with it a high proportion of all catastrophic cervical spine injuries in the game of rugby [1]. Recently, governing bodies trailed rugby law changes, as lowering the tackle height, in an attempt to minimise concussion occurrence. However, this law change could potentially increase the risk of catastrophic neck injuries if inappropriate tackling positions are adopted. Computer modelling and simulation can provide key insight to support decision making processes through the estimation of the internal loads experienced during tackling [2]. The aim of this study was to investigate the effect of different tackling techniques on the neck internal loading using a musculoskeletal model, with the final view to inform the design of rugby tackle law changes. The parameters used in the analysis to modify the tackle technique were the tackler’s neck and trunk angles at impact, and tackler’s approaching speed.


One professional academy-level front-row rugby player (male, 22 years, 1.82 m, 113.7 kg) participated in this study. Experimental kinematics and neck muscles electromyography data was collected during staged rugby tackling trials. A subject-specific OpenSim musculoskeletal model [2] was firstly used in EMG-assisted inverse simulations to estimate neck muscles activation, and then inputted in forward dynamics simulation (n=2124) where neck angles (n=117), approaching speed (n=2), and trunk angle (n=6) were changed iteratively. The impact between the tackler with the ball carrier was modelled through a Hertzian contact model, where the geometric interaction of spheres was defined to approximate the relative size and stiffness of the tackler’s head and ball carrier’s torso/trunk (Figure 1). All impacts were carried out in the sagittal mid-line (i.e. front-on tackle), which simulated the worst-case scenario of head-on impacts. The effects of these tackle parameters on the maximal compressive loading, anteroposterior shear loading and flexion bending moment were tested using a generalised linear mixed model during a 50 ms impact simulations.

The mixed model analysis showed that the neck flexion angles had the largest significant effect on maximal compressive loads, which decreased by approximately 50% as the neck transitioned from 30° flexion to 30° extension (from 2900 N to 1500 N) at the instant of impact. Lower tackling velocity had a smaller but significant effect on shear loads but considerably reduced neck compressive loading. A lower tackle height (i.e. lower tackler’s trunk angle) significantly increased the compressive loading across the cervical spine levels. Finally, evidences of buckling of the cervical spine column was also observed in the cervical spine kinematics and loading during higher speed collisions when the head, neck and torso were aligned with the oncoming ball carrier.

These results highlight the importance of correct tackle technique, and the relatively lower compressive spinal loads experienced if the neck is extended compared to when flexed. Consideration should be taken regarding the likely increase of catastrophic neck injuries during head-on collisions when reducing tackle height in rugby.
Original languageEnglish
Title of host publicationAbstract Book of the 9th World Congress of Biomechanics, 10-14 July 2022, Taipei
Publication statusPublished - 10 Jul 2022

Keywords

  • rugby
  • cervical spine
  • injury prevention

Fingerprint

Dive into the research topics of 'Rugby Tackle Height: head-down and low tackle height increase the cervical spine injury risk'. Together they form a unique fingerprint.

Cite this