A Biomechanical Analysis of the Karate Chop

Abstract Cinematography, accelerometry, and electromyography were used to study the preimpact movements of the arm and trunk during karate chops intended to break two or three 3/4-in. pine boards. Six experienced subjects were used to provide initial descriptive information from which three broad classifications of movement patterns were made. Subsequent analysis was limited to the subjects whose movements were confined principally to the sagittal plane. A kinematic analysis showed a sequential pattern of action at the shoulder and elbow joints, with shoulder extension normally 70% complete before elbow extension began. Angular velocities at the elbow joint reached 24.5 and 29.5 radians/sec for two and three boards, respectively. The component of linear acceleration, perpendicular to the forearm at the wrist, was a maximum of 7 g in both cases, as recorded by direct measurement. A second estimate of acceleration was obtained from numerical double differentiation and this showed considerable variation from the accelerometer measurement. Electromyography supported the finding of the sequential pattern of action at the shoulder and elbow joints by revealing a sequential pattern of muscular action. Triceps brachii activity was only 200 msec in duration and some activity in the biceps brachii was present immediately before impact.