Intercriteria Decision-Making Method for Speed and Load Effects Evaluation on Upper Arm Muscles in the Horizontal Plane

Speed and load effects on the number and type of pair interactions between six elbow and shoulder muscles or muscle (m.) heads were evaluated by the intercriteria decision-making method (ICrA). The surface electromyography (sEMG) signals of the m. deltoideus pars clavicularis (Dcla), m. deltoideus pars spinata (Dspi), m. biceps brachii (BB), m. triceps brachii caput longum (TB), m. brachialis (BR), and m. anconeus (AN) of ten healthy subjects were recorded. The data was collected during cycling movements (CMs) for continuous flexions and extensions in the elbow joint in the horizontal plane. The CMs were performed with and without an added load at four different speeds. The obtained sEMG data were subjected to the ICrA to identify muscle activity and speed correlations. The ICrA results demonstrate that added load resulted in a higher number of consonance relations between muscle activities. Positive consonance (PosC) appears between the Dcla-Dspi, Dspi-BR, BB-BR, and TB-BR criteria pairs for the loaded flexion phases. When extension is in the focus, Dcla-BB is in a consonance relation for no loaded phases, while for the loaded ones, five muscle pairs, namely Dcla-BB, Dcla-BR, Dspi-BR, BB-BR, and TB-BR, hit PosC. Also, the most correlations are found for the fastest phase (1 s) of flexion and extension, regardless of the load. Additionally, correlation dependencies between the two faster (Sp2-Sp1) and the two slower speeds (Sp10-Sp6) were found.