Analysis of GRF by Means of Wavelet Transform for the Performance Diagnosis of Weight Lifter**This work is partially supported by CNSF Grant #60505012 to Q. J. Song and #60575054 to Y.Yu

Weightlifting is one of the most physically demanding sports. A successful lift is influenced by many factors. Among them, the ground reaction force (GRF) which is exerted on weight lifers during the motion process is crucial to the performance of a weight lifer, so the acquisition and analysis of GRF is very important to the scientific research of weightlifting. This paper describes GRF acquisition using a force platform and analysis by means of wavelet transform (WT) for the performance diagnosis of weight lifters. The differences of GRF between the skilled weight lifters and the learners are reported. The method allows to detect and to quantify details not easily perceivable by coaches through traditional techniques. By wavelet transform of the GRF, it is possible for biomechanics experts to analysis mechanical behaviours of athletes and to direct them to improve their skills. GRF acquisition and analysis provides a very important tool for modern athletes training.