A major concern in competition taekwondo is the injury potential posed by many of the powerful kicks used. An investigation of the kinetics of four kicks frequently used in competition was performed with high speed video. Velocities were measured, and energy was calculated. Typical values for basic swing kicks were 15 ms-1 and 200 J. Basic thrust kicks possessed 45% less velocity but 28% more energy than swing kicks. Linkage models were developed to simulate the motion and kinetics of the kicking leg. Injury potential was evaluated through thoracic compression and viscous criterion models. These models predict a significant probability of serious injury with all kicks, with thoracic deflections from 3 to 5 cm and peak viscous tolerance values from 0.9-1.4 ms-1, when no protective body equipment is used.