Introduction. The quality of the lessons conducted is influenced by among others, the test results of biomechanics in the sphere of the teachings of sport and science of physical education. Therefore, the aim of this research was to obtain knowledge about the influence of selected external factors on the loads of the lower limbs during Gyaku-Zuki karate punch. Material and Methods. The analyses took into account a Karate athlete holding 2nd dan black belt. During the examination, he was performing right and left Gyaku-Zuki punch starting from zenkutsu-dachi (without
a physical target or into a board measuring 30 × 20 cm and one inch thick). Two dynamometric Kistler platforms (Kistler force plate, Type 9286AA, Kistler, Switzerland) were used for examination. The maximum ground pressure (P) for the left and right leg during Gyaku-Zuki performance was recorded while the Karate athlete was hitting the wooden board or had no target (into the air). Results. The following values were registered: punch without target – front foot 1150.27-1329.72 N,
back foot 621.78-748.13 N; punch on the board: front foot 912.28-697.76 N, back foot 721.44-670.63 N. Conlusions. The research conducted indicates that during the course of administering a blow with the fist, namely Gyaku-Zuki, the leg thrust forward bears more weight (the leg opposed to the hand administering the blow). The occurrence of a motionless object that constitutes the target of the blow, or its lacking, have an impact on the pressure force on both feet of the karate fighter, while blows administered to a wooden board reduces the pressure force of the feet on the floor.