CLASSIFICATION OF PARASPINAL MUSCLE IMPAIRMENTS BY SURFACE ELECTROMYOGRAPHY

The purpose of this article is to provide an overview of research to d evelop surface electromyographic (EMG) measurements for classification of paraspinal muscle impairments in persons with low back pain (LBP). The process of developing laboratory and clinically based protocols i s described. Results of studies to evaluate the reliability of these m easurements and their relationships with impairments and function are discussed. Research efforts to incorporate EMG spectral measurements, such as the median frequency, into a classification system to identify different types of muscle impairments are documented. Discriminant fu nctions have been calculated based on case-control studies to identify 2 kinds of LBP impairments from constant-force isometric tasks: (1) e xcessive fatigue due to muscle deconditioning and (2) inhibition of mu scle activation secondary to pain or pain-related behaviors. New areas of investigation designed to improve the classification accuracy of s uch functions using procedures other than discriminant analysis are de scribed. Work in progress to extend the application of the technique t o tasks other than those involving just isometric contraction, includi ng those involving repetitive trunk movement, is also described.