A KINEMATIC ANALYSIS OF JERK TECHMQUE IN OLYMPIC WEIGHTLIFTING

Abstract

It has been reported that the majority of failures in the performance of the clean and jerk lift in weight lifting competition, including the Olympic Games, are due to unsuccessful jerks. In an attempt, therefore, to determine the reason(s) of the poor rate of success in jerk, successful (2) and unsuccessful (I) jerks performed by a highly skilled weight lifter in a competition environment were kinematically analyzed. Three lifts (including an American record, and an unsuccessful attempt), performed at the 1988 U.S. National Weightlifting Championships, were videotaped at 60 Hz and analyzed utilizing an Ariel Performance Analysis System (APAS). Two dimensional position data of 14 body points and the center of both ends of the barbell were digitally smoothed before being submitted to further analysis. The results revealed that the successful American record lift was characterized by greater duration, barbell displacement and knee, hip and ankle joint flexion during the dip or half-squat phase of the jerk. In addition, in the unsuccessful American record attempt, the bar was driven forward substantially more than the two successful lifts. and the hip, knee and ankle joint angles in the split-squat position were smaller than in the successful lifts. A large sample of successful/unsuccessful trials must be studied before definite conclusions regarding the reasons for success/failure are reached.