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A DOWNWARD HEAD POSTURE LEADS TO HIGHER CERVICAL SPINE LOADING DURING HEAD-FIRST IMPACTS IN SIMULATED RUGBY TACKLES
  1. Elena Seminati,
  2. Ezio Preatoni,
  3. Grant Trewartha,
  4. Keith Stokes,
  5. Sean Williams,
  6. Dario Cazzola
  1. Department for Health, University of Bath, Bath, United Kingdom

    Abstract

    Background A rugby tackle is an open and unpredictable event, which can lead to intentional or unintentional head-first impacts rather than the preferred ‘shoulder first’ technique.

    Objective To identify the effect of head-neck orientation as well as collision speed on the loads experienced at the upper cervical spine and the relevance in terms of injury risk from head-first impacts.

    Design Repeated ‘tackles’ were simulated using a 40 kg punch bag (simulated ball carrier) making contact against a fixed instrumented head and neck anthropometric test device (ATD).

    Setting Biomechanics laboratory.

    Patients (or Participants) A single head-neck ATD was used to complete all the trials.

    Interventions (or Assessment of Risk Factors) 10 repetitions were recorded in each of two speed ranges (low and high) and 3 ATD sagittal plane orientations (head-up [+20°], neutral [0°], and head-down [-20°]), 60 trials in total.

    Main Outcome Measurements Forces experienced at the equivalent of the C1 vertebra were measured by a load cell at the head joint of the ATD. ANCOVA (covariate=punch bag speed) and effect sizes were used to assess differences between tackle conditions.

    Results Low speed (2.34±0.18 m/s) tackles resulted in 37% lower peak impact forces compared with high speed (3.43±0.17 m/s) tackles. Total force on neck acted in multiple directions (75% in compression; magnitude of total force was 2.37±0.18 kN in neutral high speed condition) and it was substantially higher in the head-down orientation compared with the neutral (13%) and head-up orientation (17%).

    Conclusions Our findings support the idea that: 1) collision speed during a tackle affects the load experienced by the head-neck structures; 2) a neutral or head-up orientation of the head is preferred to a head-down orientation in the event of head-first impacts during simulated rugby tackle, which aligns with current Rugby Union coaching recommendations.

    • Injury

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