Influence of the new starting block with back plate on the kinematic variables of the swimming start

Abstract

The swim start is the first component of a swimming race and although it is the shortest and the fastest phase, an effective start performance is essential for the success of a race, particularly in short events. The swim start allows swimmers to enter into the water faster than average swimming speed. Historically swimmers have performed several start techniques in competitions, whereas today the kick-start is the most popular technique due to its great advantages. This start technique is characterized by an asymmetrical position of the swimmer´s feet on the starting block where the front foot is placed on the front edge and the rear foot is placed on a stable and adjustable surface on the rear edge of the block. This surface also referred to as back plate provides higher stability and the advantage is that the swimmer is able to develop larger force levels on the block than with older techniques (grab start or track start). Among all variables included in the biomechanical analysis of the swimming starts, the angular momentum is a relevant variable due to its influence on the body position at the water entry and subsequently on the water phase performance. However, only a few studies focussed on the comparison of the different start techniques including the analysis of angular momentum data. Those studies comparing different starting techniques only analyse the amount of angular momentum produced at take-off and no study evaluates the development of the angular momentum during the block phase; flight phase and/or glide phase in a swimming start. The main objective of this thesis is to study the kick-start performance by analysing the development of angular momentum. Additionally, this study highlights the advantages in terms of angular momentum and body rotation swimmers provide to the kick-start. After a general introduction about the history, evolution and relevance of swim starts, and a brief description of the theoretical background about angular momentum, the thesis is divided into two chapters. Chapter 1 determines the most relevant factors for the improvement of the kick-start and Chapter 2 focuses on the analysis of the development of angular momentum about the mediolateral body axis from the starting signal until the gliding phase in the kick-start technique.