Motor unit synchronization is reduced in anterior knee pain

Mellor, Rebecca and Hodges, Paul W. (2005) Motor unit synchronization is reduced in anterior knee pain. Journal of Pain, 6 8: 550-558. doi:10.1016/j.jpain.2005.03.006

Author Mellor, Rebecca
Hodges, Paul W.
Title Motor unit synchronization is reduced in anterior knee pain
Journal name Journal of Pain   Check publisher's open access policy
ISSN 1526-5900
Publication date 2005-08-01
Year available 2005
Sub-type Article (original research)
DOI 10.1016/j.jpain.2005.03.006
Open Access Status Not yet assessed
Volume 6
Issue 8
Start page 550
End page 558
Total pages 9
Editor G. Gebhart
Place of publication Edinburgh
Publisher Churchill Livingstone
Language eng
Subject C1
320700 Neurosciences
321403 Motor Control
730303 Occupational, speech and physiotherapy
Abstract Anterior knee pain (AKP) is common and has been argued to be related to poor patellofemoral joint control due to impaired coordination of the vasti muscles. However, there are conflicting data. Changes in motor unit firing may provide more definitive evidence. Synchronization of motor unit action potentials (MUAPs) in vastus medialis obliquus (VMO) and vastus lateralis (VL) may contribute to coordination in patellofemoral joint control. We hypothesized that synchronization may be reduced in AKP. Recordings of single MUAPs were made from VMO and multiunit electromyograph (EMG) recordings were made from VL. Averages of VL EMG recordings were triggered from the single MUAPs in VMO. Motor units in VL firing in association with the VMO motor units would appear as a peak in the VL EMG average. Data were compared to previous normative data. The proportion of trials in which a peak was identified in the triggered averages of VL EMG was reduced in people with AKP (38%) compared to controls (90%). Notably, although 80% of subjects had values less than controls, 20% were within normal limits. These results provide new evidence that motor unit synchronization is modified in the presence of pain and provide evidence for motor control dysfunction in AKP. Perspective: This study shows that coordination of motor units between the medial and lateral vasti muscles in people with anterior knee pain is reduced compared to people without knee pain. It confirms that motor control dysfunction is a factor in this condition and has implications for selection of rehabilitation strategies. (c) 2005 by the American Pain Society.
Keyword Motor Unit
Vasti Muscles
Motor Control
Patellofemoral Pain
Clinical Neurology
Vastus Medialis Obliquus
Experimental Muscle Pain
Feedforward Postural Responses
Short-term Synchronization
Electromyographic Activity
Lateralis Muscles
Trunk Muscles
Q-Index Code C1
Institutional Status UQ

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Created: Wed, 15 Aug 2007, 15:57:01 EST