Associations between ground reaction force waveforms and sprint start performance

• Published in: International journal of sports science & coaching Vol. 14; no. 5; pp. 658 - 666
• Main Authors: Colyer, Steffi L, Graham-Smith, Philip, Salo, Aki IT
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.10.2019
• Subjects: sport biomechanics; track-and-field athletics; sprint running; kinetics; starting blocks; Centre of mass
• ISSN: 1747-9541; 2048-397X
• DOI: 10.1177/1747954119874887

Ground reaction forces produced on the blocks determine an athlete’s centre of mass motion during the sprint start, which is crucial to sprint performance. This study aimed to understand how force waveforms are associated with better sprint start performance. Fifty-seven sprinters (from junior to world elite) performed a series of block starts during which the ground reaction forces produced by the legs and arms were separately measured. Statistical parametric mapping (linear regression) revealed specific phases of these waveforms where forces were associated with average horizontal external power. Better performances were achieved by producing higher forces and directing the force vector more horizontally during the initial parts of the block phase (17–34% and 5–37%, respectively). During the mid-push (around the time of rear block exit: ∼54% of the block push), magnitudes of front block force differentiated performers, but orientation did not. Consequently, the ability to sustain high forces during the transition from bilateral to unilateral pushing was a performance-differentiating factor. Better athletes also exhibited a higher ratio of forces on the front block in the latter parts of unilateral pushing (81–92% of the block push), which seemed to allow these athletes to exit the blocks with lower centre of mass projection angles. Training should reflect these kinetic requirements, but also include technique-based aspects to increase both force production and orientation capacities. Specific training focused on enhancing anteroposterior force production during the transition between double- to single-leg propulsion could be beneficial for overall sprint start performance.