This study analyses the reaction forces and variations of rock climbing in vertical and overhanging positions. Subjects voluntarily released their right foot and regained equilibrium. In the overhanging position the quadrupedal state was characterised by a significant involvement of the arms to prevent fall. Moreover, the horizontal forces applied to the holds were less important, which suggests that equilibrium was easier to maintain than in the vertical position. The tripedal state was characterised by less extensive contralateral supporting force transfer on the remaining holds in the overhanging position, which reinforces safety.