Study aim: estimate reaction forces and muscle torque in lower limb joints during the Naeryo chagi technique in taekwondo.Material and methods: the parameters of the Naeryo chagi kick were measured with a Vicon motion tracking system comprising ten MX T40S cameras, two reference cameras and four AMTI BP600900-2000 force plates. Additional measurements were performed using the BTS-4AP-2K force analysis system equipped with a WB-4AP punching bag. The acquired raw data were processed and synchronized using Matlab v.R2007a software. A computer simulation created on the basis of the adopted mathematical model was used to identify reaction forces and control moments.Results: the highest joint loads occurred at the moment when the striking leg reversed its movement direction from rising to rapidly falling towards the target. The knee and ankle joints of the supporting leg were subject to greatest reaction forces and muscle torque.Conclusions: it is recommended to follow an exercise routine aimed at strengthening and stabilizing the structures of motor system subject to the greatest load.