Head impact forces in rugby tackles are influenced by tackler position and the ball carrier instantaneous speed at contact in front-on, one-on-one tackle scenarios

Suzi Edwards; Andrew J Gardner; Kenneth L Quarrie; Timana Tahu; Gordon W Fuller; Gary Strangman; Grant L Iverson; Ross Tucker

doi:10.1016/j.jsampl.2025.100121

Head impact forces in rugby tackles are influenced by tackler position and the ball carrier instantaneous speed at contact in front-on, one-on-one tackle scenarios

JSAMS Plus. 2025 Nov 26:6:100121. doi: 10.1016/j.jsampl.2025.100121. eCollection 2025 Dec.

Authors

Suzi Edwards¹, Andrew J Gardner¹, Kenneth L Quarrie^{1

2}, Timana Tahu¹, Gordon W Fuller³, Gary Strangman⁴, Grant L Iverson^{5

6

7}, Ross Tucker⁸

Affiliations

¹ Sydney School of Health Sciences, The University of Sydney, Camperdown, NSW, Australia.
² New Zealand Rugby, 100 Molesworth Street, Thorndon, Wellington, New Zealand.
³ Emergency Medicine Research in Sheffield Group, School of Health and Related Research, University of Sheffield, Sheffield, UK.
⁴ Neural Systems Group, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.
⁵ Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, USA.
⁶ Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital and the Schoen Adams Research Institute at Spaulding Rehabilitation, Charlestown, MA, USA.
⁷ Mass General for Children Sports Concussion Program, Boston, MA, USA.
⁸ World Rugby, Pty (Ltd), Dublin, Ireland.

Abstract

Background: It is not well understood how tackling technique influences the inertial head kinematics of a tackler or ball carrier. This study identified the modifiable components of the tackler's technique (including instantaneous speed at contact) that predicted inertial head kinematics of a male tackler and ball carrier during a front-on, one-on-one, 'slow speed' rugby tackle.

Methods: Three-dimensional motion capture recorded 455 torso tackles across 15 rugby players. Principal component analysis identified four significant tackle related variables: 'flexed head-kyphotic posture'; 'body height lowering strategy'; 'instantaneous speed at contact-ball carrier'; 'instantaneous speed at contact-tackler'.

Results: The ball carrier's instantaneous speed at contact, not the tackler, predicts inertial head kinematics of the tackler's and ball carrier's inertial head kinematics (p < 0.05). Tacklers that adopt a more 'flexed head-kyphotic posture' (i.e., they were looking downwards towards the ground, adopted a kyphotic posture), resulted in higher inertial head kinematics for the tackler but lower inertial head kinematics for the ball carrier (p < 0.001). A tackler with a 'body height lowering strategy' resulted in higher inertial head kinematics for both players (p < 0.001) by tilting their pelvis forward to primarily flex their hips, and adopting an upright trunk posture with a neutral lordotic posture.

Conclusion: To reduce the tackler's peak inertial head kinematics, the tackler could adopt a tackle strategy that looks upwards (i.e., not looking to the ground) and adopts partially bent-at-waist (i.e., is not upright) and avoids a kyphotic posture or tilting their pelvis forward to primarily flex their hips to lower their body height.

Clinical trial registration: This is not a clinical trial.

Keywords: Acceleration; Biomechanics; Concussion; Head; Motion capture.