Most of motions used in physical education and sports require generation of a great amount of mechanical energy and its effective use to achieve good performance. The purpose of this study was to investigate effects of technical training on the takeoff motion and mechanical energy-related parameters in the standing long jump. Twenty-one male adults were participated in the technical training session for two days, which was designed to improve the jumping technique and jumping distance of the standing long jump. Jumping motion of the subjects was videotaped with a high-speed video camera and ground reaction forces were measured with a force platform in pre and post training sessions. A two-dimensional motion analysis technique was used to calculate total mechanical work (Wtotal), effectiveness index of mechanical energy utilization (EI), joint force power (JFP) and segment torque power (STP).

After the technical training, the subjects increased the forward lean of the body at the instant of the takeoff. This change resulted in the more forward extended takeoff position and the increase in the horizontal takeoff velocity as well as the jumping distance. There were two types of change in mechanical energy-related parameters by the technical training. One was an EI+ type which increased EI but decreased Wtotal, and another was a Wtotal+ type which increased Wtotal but decreased EI. The EI+ type decreased the mechanical energy flow, especially to the trunk from the legs and the trunk backward rotation, while the Wtotal+ type increased both. These results indicated that the two-day technical training of the standing long jump was able to improve not only the jumping distance but also the takeoff technique, and that the effects could be categorized by the mechanical energy flow to the trunk from the legs and the change in the trunk rotation during the takeoff phase.