Neck muscle fatigue and postural control in patients with whiplash injury

Paul J. Stapley, Maria Vittoria Beretta, Elena Dalla Toffola, Marco Schieppati

Research output: Contribution to journalArticlepeer-review


Objectives: To examine if patients with whiplash injury show identifiable increases in neck muscle fatigability and associated increase in postural body sway after contractions of dorsal neck muscles, and if physiotherapy treatment reduces these effects. Methods: Sway was measured during stance in 13 patients before and after 5 min of isometric dorsal neck muscle contractions and after recovery, pre- and post-physiotherapy, using a force platform. Amplitude and median frequency of neck muscle EMG were calculated during the contracting period. After each stance trial, patients gave a subjective score of sway. Results: Pre-treatment, seven patients showed EMG signs of fatigue (increases in amplitude, decreases in median frequency) and increases in sway (eyes closed) after contractions. The other patients showed neither fatigue nor increased sway. Post-treatment, no signs of fatigue or imbalance were recorded in all patients, for the same levels of muscle contraction. Conclusions: As in normal human subjects, increases in sway are associated with signs of neck muscle fatigue in some whiplash injury patients. Physiotherapy decreases the susceptibility to fatigue of neck muscles and is an effective choice of treatment of subjective instability and sway. Significance: This study demonstrates a pathophysiological link between neck muscle fatigue and impaired postural control, and also that physiotherapy can relieve symptoms and signs of impaired neck muscle function by reducing muscle fatigability.

Original languageEnglish
Pages (from-to)610-622
Number of pages13
JournalClinical Neurophysiology
Issue number3
Publication statusPublished - Mar 2006


  • EMG
  • Fatigue
  • Isometric contraction
  • Neck muscles
  • Posture
  • Whiplash injury

ASJC Scopus subject areas

  • Clinical Neurology
  • Radiology Nuclear Medicine and imaging
  • Neurology
  • Sensory Systems
  • Physiology (medical)

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