Electromyographic assessment of muscle fatigue after the Biering-Sorensen test in subjects with low back pain who underwent the McKenzie treatment.

Purpose: Chronic low back pain is a common disorder affecting about 80% of the population, caused by a disorder in the muscular system. The main aim of this study was to assess muscle fatigue during the Biering-Sorensen Test in people with chronic low back pain who underwent the McKenzie treatment.

Methods: Tests were conducted on 19 men (mean age of 41.4 years) with chronic non-specific lumbar-sacral pain syndrome, working in the seated position in front of a computer. Assessment of changes in fatigue of erector spinae, gluteus maximus and biceps femoris using surface electromyography during the Biering-Sorensen Test and subjective pain assessment using Visual Analog Scale were conducted on three test dates. Time-frequency representation of the electromyographic signal (Fourier transform) was used for the examination of muscle fatigue. The McKenzie method of diagnosis and therapy was applied before and between the tests.

Results: The McKenzie therapy resulted in increased endurance (test duration) of the examined spinal muscles between the 1st and 3rd test date ( p = 0.043), and a systematic decrease in pain assessment on the three test dates ( p = 0.000-0.004). Correlations were obtained between slope coefficients of the simple regression of median frequency of electromyographic signals on the one hand and duration of the BST ( p = 0.000-0.012) and anthropometric parameters (body mass, height and body mass index, p = 0.001-0.020) on the other.

Conclusions: The McKenzie method is an effective tool in reducing the level of lumbar pain and improving muscle endurance.