Far-field potentials in muscle.

Far-field potentials have been predicted by computer simulations as well as demonstrated in both animals and humans with respect to the peripheral and central nervous systems. Computer simulations have also predicted far-field potentials originating at the termination of muscle tissue. This investigation demonstrates the occurrence of 2 far-field potentials in the human biceps muscle resulting from action potential termination at the musculotendonous junctions. A monophasic potential is produced at both the muscle's origin and insertion, and the polarity is entirely dependent upon the recording montage. Sequential stimulation of the biceps muscle at 2.5-cm increments resulted in the 2 far-field potentials and their respective latencies changing proportional to the distance between the stimulus site and the 2 musculotendonous junctions. Various stimulation and recording montages are used to investigate the properties of these far-field potentials. The leading/trailing dipole model is utilized to explain the production and polarity of far-field potentials generated by muscle tissue.