ANGULAR MOMENTUM ANALYSIS OF MEN’S DISCUS THROWERS IN 1998 USA TRACK & FIELD CHAMPIONSHIPS

Abstract

Twenty-five discus throwers for USA Track & Field Championships 1998 were videotaped and analyzed using the three-dimensional (3D) DLT method. 3D coordinates of body segments and discus were then obtained. Angular momentum (H) of the thrower and discus was calculated using the link-segmental inverse dynamics approach. Positive HZ for the thrower-plus-discus system was produced during the initial double-support and first single-support phases. Negative HX for the system was a large increase, prior to, or in correspondence with the increase of the negative HY, during the latter half of the second single-support phase and the delivery phase. It seems reasonable to conclude that the increase of vertical speed of the discus (negative HY of the system) results from the interaction between the positive HZ and the negative HX of the system during the second single-support and delivery phases. This paper discusses the mechanism (“Gyro Model”) for the discus throwing motion, based on the principle of the gyroscope.