The purpose of this study is to analyze the changes in centers-of-gravity (COG), acceleration and body posture and their associated effects both on EMG and on the maximum capability of weight lifting during Clean & Jerk and Snatch motions. Displacement, velocity, acceleration of joints were obtained from film analysis. Also levels of exertions on 11 major muscle groups were obtained from EMG analysis during a lifting cycle. The EMG data were measured from Telemetry System which is useful in field experiments. Magnitude and direction of force, change in center-of-gravity were extracted from COG data which were measured from force platform. The results of this study can be to be useful both to coaches and to athletes in weight-lifting.