Journal of Manipulative and Physiological Therapeutics
Volume 29, Issue 2 , Pages 115-125, February 2006

The Effect of Seat Belt Use on the Cervical Electromyogram Response to Whiplash-Type Impacts

  • Shrawan Kumar, PhD, DSc

      Affiliations

    • Department of Physical Therapy, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada
    • Corresponding Author InformationSubmit requests for reprints to: Sharwan Kumar, PhD, DSc, Department of Physical Therapy, Faculty of Rehabilitation Medicine, 3-75 Corbett Hall, University of Alberta, Edmonton, AB, Canada T6G 2G4
    • ,
  • Robert Ferrari, MD

      Affiliations

    • Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
    • ,
  • Yogesh Narayan, PEng

      Affiliations

    • Department of Physical Therapy, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada
    • ,
  • Troy Jones, BScPT

      Affiliations

    • Department of Physical Therapy, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada

Received 18 April 2005; received in revised form 23 June 2005

Abstract 

Objective

The objective of this study was to determine the effect of a standard 3-point lap-and-shoulder seat belt and car seat on the electromyogram (EMG) response of the cervical muscles to increasing low-velocity impacts in comparison with that of a rigid seat and 5-point restraint.

Methods

Seventeen healthy volunteers were subjected to rear, frontal, right and left lateral and bilateral anterolateral, and posterolateral impacts with an acceleration varying from 4.4 to 16.8 m/s2 while in a car seat with lap-and-shoulder seat belt.

Results

For rear-end impacts, whether straight on, right posterolateral, or left posterolateral, all muscles generated 50% or less of the maximal voluntary contraction (MVC) EMG. In straight-on rear impacts, the sternocleidomastoid was symmetrically the most active; however, in posterolateral impacts, the sternocleidomastoid contralateral to impact direction was more active than its counterpart. For a right lateral impact, at the highest acceleration, the left splenius capitis generated 47% of its MVC and the left trapezius did 46% of its MVC. In a left lateral impact, the right splenius capitis generated 48% of its MVC and the right trapezius did 57% of its MVC. In a straight-on frontal impact, the left trapezius generated 35% of its MVC and the right trapezius did 48% of its MVC. In a left anterolateral impact, the right splenius generated 60% of its MVC and the right trapezius did 66% of its MVC. Similarly, in a right anterolateral impact, the contralateral splenius muscle increased its activity to 52% of its MVC and the left trapezius was at 52% of its MVC.

Conclusions

Compared with previously reported impact studies with a rigid seat and 5-point harness, the use of a 3-point lap-and-shoulder seat belt with a standard car seat did not appear to adversely affect cervical muscle response. In very-low-velocity and low-velocity impact experiments, seat belt and seat type may not significantly alter cervical EMG and kinematics.

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 Sources of support: No funds were received for the preparation of this manuscript.

PII: S0161-4754(05)00370-2

doi:10.1016/j.jmpt.2005.12.008

Journal of Manipulative and Physiological Therapeutics
Volume 29, Issue 2 , Pages 115-125, February 2006

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