Archives of Physical Medicine and Rehabilitation
Volume 87, Issue 4 , Pages 496-503, April 2006

An Observational Electromyography Study of the Effect of Trunk Flexion in Low-Velocity Frontal Whiplash-Type Impacts

  • Shrawan Kumar, PhD (FRS(C))

      Affiliations

    • Department of Physical Therapy, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
    • Corresponding Author InformationReprint requests to Shrawan Kumar, PhD, FRS(C), 3-75 Corbett Hall, Dept of Physical Therapy, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB T6G 2G4, Canada
    • ,
  • Robert Ferrari, MD (FRCPC, FACP)

      Affiliations

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

      Affiliations

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

Abstract 

Kumar S, Ferrari R, Narayan Y. An observational electromyography study of the effect of trunk flexion in low-velocity frontal whiplash-type impacts.

Objective

To examine the effect of forward and lateral trunk flexion on the cervical electromyogram and head kinematic response to whiplash-type frontal impacts.

Design

Observational study of sled impacts.

Setting

Laboratory.

Participants

Twenty healthy volunteers.

Intervention

Twenty volunteers were subjected to increasing low-velocity (<8km/h) frontal impacts of 4.4, 7.6, 10.3, and 13.3m/s2 acceleration with trunk forward flexed by 45° and laterally flexed to the right and left by 45°.

Main Outcome Measures

Bilateral electromyography of the sternocleidomastoids, trapezii, and splenii capitis and acceleration of the sled, torso, and head were recorded.

Results

With either direction of lateral trunk flexion at impact, the trapezii electromyographic activity increased with increasing acceleration (P<.05). With the trunk flexed to the left, the left trapezius generated 39% of its maximal voluntary contraction (MVC) electromyographic activity, while the right trapezius generated 31% of its MVC electromyographic activity. The left splenius (ipsilateral to leftward trunk flexion) generated 24% of its MVC electromyographic activity, with all other muscles generating 15% or less of this measure. With the trunk flexed to the right, the right trapezius generated 38% of its MVC electromyographic activity, while the left trapezius generated 32% of this value. Again, the ipsilateral (to trunk flexion) splenius capitis generated 27% of its MVC electromyographic activity, and all other muscles 11% or less of this measure.

Conclusions

When subjects sit with trunk flexed out of neutral posture at the time of frontal impact, the cervical muscle response is low and unlikely to be injurious.

Key Words:  Electromyography , Muscles , Rehabilitation , Whiplash injuries

 

 No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated.

PII: S0003-9993(05)01533-9

doi:10.1016/j.apmr.2005.12.034

Archives of Physical Medicine and Rehabilitation
Volume 87, Issue 4 , Pages 496-503, April 2006

Article Tools

* Image Usage & Resolution