Swimming start model and determination of the optimal breakout position.

While many parameters contribute to swimming start performance, a few have been proven to affect the overall start performance more significantly than others; these include take-off velocity, flight time, entry water distance, time underwater during descent and ascent, and free-swimming velocity. This study aims to analyse the influential trajectory of these key parameters on the overall start performance, particularly focusing on determining the optimal breakout point. Ten national-level swimmers participated in this study, which combined kinematics and statistical analysis to propose a novel start model that can be used to explore the influential trajectory of key parameters on the overall start performance and assess the effect of some training factors for performance improvement. Further, this study investigated the optimal breakout position via a mathematical model. This is the first study to provide a solution to determine this parameter. The solution is verified to be practical through trial data, and the overall start performance is improved by 0.71-3.29%, depending on the swimmer's current level. Therefore, the results can be used as a reference for swimming start training and improvement.