Manifestation of morphofunctional specificity of muscles in spectral evaluations of the surface electromyogram.

Abstract It is shown that, when the global recording method is used, the muscles of upper limbs (in comparison with lower ones) and of distal parts of limbs (in comparison with proximal ones) generate wider surface electromyograms (EMGs) with a higher dominant frequency and lower saturation of power spectra owing to the specific features of the morphofunctional organization of both the muscles proper and corticospinal systems controlling their voluntary contractive activity. There is an interrelation among different spectral and amplitude-frequency response (EMG analysis according to Willison) characteristics of the surface EMG. Limb lengthening may be considered, on the basis of criteria of changes in spectral characteristics of the EMG of lengthened segment muscles and results of its analysis according to Willison, as a model of a decrease in reliability of corticospinal connections. [ABSTRACT FROM AUTHOR]