Skill reproduction in a reduced time-frame by martial athletes

Taekwondo (TKD) and karate are martial sports which require athletes to reproduce whole-body complex skills in reduced time-frames during competition. It is important to determine whether differences exist between training 'maximum' (normal) and competition 'maximum' (100%) modes of execution of a movement combination, to ensure training executions adequately and specifically reflect those in competition. Three-dimensional analyses of five athletes from each sport were conducted. Kinematic differences between execution modes were measured and the kinetic causes for these differences were investigated and related to the motor control involved in these martial arts combinations. The analysis used a fourteen-segment representation of the martial athlete, incorporating both functional and predictive joint centres and subject specific inertia data, and was designed to best represent the explosive movements observed in both sports. The study showed that athletes lowered the execution times of their combinations in 100% mode, but did so using different strategies. If contact velocities of a technique increased this was achieved by increasing the peak velocity alone, if it decreased this was due to a lower peak velocity and a different deceleration pattern. The striking limb showed few angle differences at target contact between execution modes. More angle differences were observed for central segments which appeared to be related to controlling the effective mass of a technique and the athletes attempting to reduce the transfer time between techniques of the combination in 100% mode. The striking limbs demonstrated low variability in joint moments, while more moment variability was observed for other joints, -particularly in the central segments. Joint moments were more variable in 100% mode even though their trends and joint angle regularity were maintained. This variability in moments may be required to keep the movement on track. TKD athletes did not optimise their kicks for maximal impact when kicking the training target pads. Karate athletes controlled energy transfer to the target when attacking the head through controlling effective mass and the moment sequencing of the striking limb, rather than velocity. Practical implications of the study were: TKD athletes should include combination training on heavy targets; combinations can be improved by focussing on the initial and transfer phases; and strengthening central and support segments may reduce chronic injury.