Abstract: A generally flat, rectangular rubber pad supports (63) discrete, non-invasive electrodes in a 7 by 9 array and a ground electrode to collect surface electromyographic (EMG) signals from an underlying muscle group of a patient. Electronic apparatus conditions the EMG signals and is programmed to survey the electrode array simultaneously to provide a description of the activity of individual muscles in the muscle group at that point in time. The description is displayed on a video monitor or the like, juxtaposed over a display of normal muscle anatomy, with differences being emphasized by color enhancement. The electrode pad is particularly suited for the lower back muscle groups and may be retained in position by a lumbar support belt having a pad molded to the contours of the human spine.