FUNCTIONAL CLASSIFICATION OF SELECTED SHOULDER MUSCLES BY ELECTROMYOGRAPHY

I summarize several studies kinesiologicals classify muscles in motor primary or accessory, based on this importance in the execution of a movement to articulate specific, it seems a clear criterion not to exist for such classification. In function of that, the objective of that study was to propose a mathematical criterion to classify the muscular function thru from electromyography activity (EMG). EMG signs were obtained of the muscles pectoralis major (clavicular head-PC), deltoid (anterior deltoid -AD and posterior deltoid -PD) and latissimus dorsi (LD) of 10 healthy subjects male. Torques were obtained from the subject’s dominant shoulder during flexion (FLX), extension (EXT) during maximal isometric voluntary contractions and during maximal (100%) and submaximal (30%) concentric contractions performed at an angular velocity of 30°/s. The used criterion was that the muscles should present great variation of the activation between the effort submaximal and maximum, and they should be more activated of the accessory muscles. The muscles PC and AD were classified as primary motors for flexion of the shoulder, because they presented great increase of the activation with increase of the effort (p < 005), and the muscle LD primary motor was considered for the extension of the shoulder (p < 005). The results suggest that the analysis of the EMG sign takes possible to classify the function of the skeletal muscles in primary motor or accessory starting from a quantitative analysis instead of the qualitative classification that is presented in most of the books of the area of the Kinesiology.