Recently Morimoto et al. (1980) reported that the electrical responses of particular single motor units could be detect by the surface electrodes with good reproducibility.
　In this communication, we would report the responses of the particular motor unit during the submaximal voluntary prolonged activity before and after the muscular training.
　The results were as follows:
　1) Before the muscular training, the discharge frequency of the motor unit during the activity decreased for 3-4 min and increased gradually. The conduction velocity decreased monotoneously during the activity.
　2) Immidiately after the training, the discharge frequency showed no large variations compared with the result obtained before the training. The decrement rate of the conduction velocity was decreased by the training.
　3) At 4 weeks after the muscular training, the discharge pattern and the decrement rate of the conduction velocity showed the similar manners to the control.
　4) The changes of the recruitment threshold values was not observed by the muscular training.

DESCENTE SPORTS SCIENCE Vol.17/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE