[application of electromyography (EMG) in recognition of lumbo-sacral back pain]

Power spectra of electromyograms (EMG) of back muscles in the lumbo-sacral area were compared in two groups of subjects. In the first one EMGs were registered in 49 young, healthy, males working in standing posture. The recordings were carried out at rest, after application of a 20 kg load and at the onset of pain. In the second group 31 subjects of both sexes and different age, suffering from intense back pain of various etiology, were investigated and compared with a group of 15 healthy persons. In the first group the power level increased after the loading, and in 42 subjects it showed further rise when the pain appeared. In the second group the power level at the range of 25 to 400 Hz, at rest, was significantly higher in the back pain patients than in healthy subjects. The results are discussed from the point of view of their applicability for the diagnosis of back pain.