With a male, adult subject, this study measured the punch force and kick force of the Japanese martial art Nihon-Kempo, the movements of the dominant (right) arm, leg, and the movements of the legs using timed synchronization. Using an electromyogram (EMG), the relationship between the variation of punch force and the variation of the electrical potential of the muscles were examined. It was observed that when the punch force was at maximum, the electrical potential of the muscles was not at maximum. The relationship between the variation of the punch force and that of the ground reaction force was experimentally analyzed. The variation of punch force based on time progression was examined. The theoretical punch force values were calculated by establishing a differential equation for a fist with a glove and a target load cell to assure the validity of our experimental equipment. This second order differential equation was transformed into two first order differential equations. Using the Runge-Kutta methods, the two first order differential equations were solved simultaneously. The calculated results were compared with the experimental data. It was found that the theoretical solutions corresponded to the experimental data. Therefore, it has been recognized that the experimental equipment functioned reliably. For the kick, it was examined that the velocity of the heel and toes became maximum around the halfway point in the kick's trajectory and hit the target load cell while reducing in velocity. It is supposed that the trial subject began the kicking motion and aimed at the target load cell while experiencing a reduction in velocity of his heel and toes due to his leg reaching maximum extension. The force of the kick, about 4500 N, was roughly 2.8 times stronger than that of the punch. (Contains 9 figures.)