Biomechanical investigations of sprint start technique and performance

Biomechanical investigations of sprint start technique and performance N. E. Bezodis, University of Bath, 2009 The start is an important part of any athletics sprint event, and has thus been the focus of considerable biomechanical research. However, relatively little is known about how differences in technique beyond the ‘set’ position can influence the consequent performance levels. A series of empirical and theoretical investigations were therefore undertaken to advance the understanding in this area. Initial investigations revealed the importance of appropriately quantifying performance. Horizontal external power production provided the most appropriate measure and was subsequently used to quantify the success associated with different aspects of technique. Block phase analyses of 13 trained and three international-level sprinters highlighted the importance of increasing hip extension and the rear leg push. It was revealed that over-extending the front ankle could impair performance due to an unfavourable increase in push duration. Empirical investigations of the first stance phase in international-level sprinters revealed the importance of configuration at touchdown positioning the stance foot further behind the centre of mass and generating a large gravitational trunk-segment moment appeared beneficial for performance. Joint kinetics patterns were identified which assisted performance by augmenting horizontal centre of mass translation during stance. To further investigate the first stance phase, a seven-segment angle-driven model was developed. Model evaluation revealed kinematic and kinetic outputs to match reality with a mean difference ranging from 5.2% to 11.1%. Individual-specific simulations identified alterations to stance leg angles at touchdown which influenced the centre of mass position and gravitational moment of the trunk, and consequently performance. Increases in the backwards velocity of the toe at touchdown and reductions in ankle dorsiflexion during early stance also improved performance by increasing the rate of horizontal force development. The combined empirical and theoretical understanding therefore highlighted several aspects of technique which could be altered in an attempt to improve sprint start performance.