Premium
Motor unit properties of biceps brachii in chronic stroke patients assessed with high‐density surface EMG
Author(s) -
Kallenberg Laura A.C.,
Hermens Hermie J.
Publication year - 2009
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.21090
Subject(s) - biceps , medicine , motor unit , chronic stroke , physical medicine and rehabilitation , stroke (engine) , biceps brachii muscle , electromyography , cardiology , anatomy , physical therapy , rehabilitation , physics , thermodynamics
The aim of this study was to investigate motor unit (MU) characteristics of the biceps brachii in poststroke patients using high‐density surface electromyography (sEMG). Eighteen chronic hemiparetic stroke patients took part. The Fugl‐Meyer score for the upper extremity was assessed. Subjects performed an isometric step contraction consisting of force levels from 5%–50% maximal voluntary contraction while sEMG of the biceps brachii was recorded with a two‐dimensional 16‐channel electrode array. This was repeated for both sides. Motor unit action potentials (MUAPs) were extracted from the EMG signals, and their root‐mean‐square value (RMS MUAP , reflecting MU size) and mean frequency of the power spectrum (FMEAN MUAP , reflecting recruitment threshold) were calculated. FMEAN MUAP was smaller on the affected than on the unaffected side, indicating an increased contribution of low‐threshold MUs, possibly related to degeneration of high‐threshold MUs. The ratio of RMS MUAP on the affected side divided by that on the unaffected side correlated significantly with the Fugl‐Meyer score. This ratio may reflect the extent to which reinnervation has occurred on the affected side. © 2008 Wiley Periodicals, Inc. Muscle Nerve 2008