ABDOMINAL ELECTROMYOGRAPHY DURING MICTURITION.

Electromyographic tracings during micturition were obtained from the abdominal muscles of volunteer men by means of silver cup electrodes. Electromyographic tracings of cough, strain and volitional and sphincter contraction were made before and after voiding on desire and on volition. While the EMG activity of cough and strain remain unchanged, that of volitional and sphincter contraction underwent various changes following both types of voiding. Before or at the onset of micturition on desire the EMG remained unchanged in ten of 14 subjects, but with cessation of micturition it remained unchanged in only seven subjects while it increased in the remaining seven. Before or at the onset of micturition on volition the EMG remained unchanged in seven of nine subjects, and with cessation of micturition it remained unchanged in eight of the nine subjects. Interruption of micturition increased the EMG activity of six among seven subjects, but resumption of micturition did not alter the EMG in five of the seven subjects. Great variations existed in regard to urinary volume and flow rate. It is proposed that there is an association of movements between the abdominal and pelvic floor muscles and that these movements are more conspicuous with cessation and interruption than with onset of physiological micturition.