Get access

Bradykinesia, muscle weakness and reduced muscle power in Parkinson's disease

Authors

  • Natalie E. Allen BAppSc (Physio) Hons,

    1. Neurological Rehabilitation Research Group, Faculty of Health Sciences, The University of Sydney, Sydney, Australia
    Search for more papers by this author
  • Colleen G. Canning BPhty, MA, PhD,

    1. Neurological Rehabilitation Research Group, Faculty of Health Sciences, The University of Sydney, Sydney, Australia
    Search for more papers by this author
  • Catherine Sherrington BAppSc (Physio), MPH, PhD,

    1. The George Institute for International Health, The University of Sydney, Sydney, Australia
    Search for more papers by this author
  • Victor S.C. Fung MB, BS, PhD, FRACP

    Corresponding author
    1. Movement Disorder Unit, Department of Neurology, Westmead Hospital, Sydney, Australia
    • Movement Disorder Unit, Department of Neurology, Westmead Hospital, PO Box 533, Wentworthville, NSW 2145, Australia
    Search for more papers by this author

  • Potential conflict of interest: Nothing to report.

Abstract

Muscle power (force × velocity) could clarify the relationship between weakness and bradykinesia in Parkinson's disease (PD). The aims of this study were to determine if patients with PD were weaker and/or less powerful in their leg extensor muscles than a neurologically normal control group and to determine the relative contributions of force and movement velocity/bradykinesia to muscle power in PD. Forty patients with PD and 40 controls were assessed. Strength in Newtons (N) was measured as the heaviest load the participant could lift. Power in Watts (W) was measured by having the participant perform lifts as fast as possible. The PD group were 172 N weaker (95% CI 28–315) and 124 W less powerful at peak power (95% CI 32–216) than controls. However, velocity at maximal power was only reduced compared with controls when lifting light to medium loads. When lifting heavy loads bradykinesia was no longer apparent in the PD group. These results suggest that reduced muscle power in PD at lighter loads arises from weakness and bradykinesia combined, but at heavier loads arises only from weakness. The absence of bradykinesia in the PD group when lifting heavy loads warrants further investigation. © 2009 Movement Disorder Society

Ancillary