A method for electromyographic analysis of muscular contraction frequencies

A method for evaluation of muscular contraction frequencies during prolonged work is presented. It is based upon computer-aided electromyographic (EMG) analyses. Variations in muscular tension, expressed as the relative force of contraction or torque in the joint, are followed using previously described EMG techniques. The number of times muscular tension crosses an amplitude band from below is then estimated. The band represents a predetermined range of amplitude. It is moved in steps from the lowest to the highest force level which occurred during the work task, and the frequency of band-crossings is computed for each band position. The frequencies are then plotted against the force levels at which the upper limit of the band was placed. From this relationship a frequency/force index is computed. The analysis is repeated several times using different band-widths. Thus, the method considers the contraction frequencies according to the load levels. It was developed to study the function of the musculo-venous pump in the legs during prolonged sedentary work, but might also be used to analyse such factors as muscular strain during work.