Sprint Start Kinetics of Amputee and Non-Amputee Sprinters.

Steffen Willwacher,Gert-Peter Brüggemann,Adam Brazil,Jan-Peter Goldmann,Volker Herrmann,Kai Heinrich,Johannes Funken,Björn Braunstein,Wolfgang Potthast,Gerda Strutzenberger,Gareth Irwin,Laurent Mourot

doi:10.1371/journal.pone.0166219

Steffen Willwacher, Gert-Peter Brüggemann + Show 10 more

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https://doi.org/10.1371/journal.pone.0166219

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Abstract

The purpose of this study was to explore the relationship between the forces applied to the starting blocks and the start performances (SPs) of amputee sprinters (ASs) and non-amputee sprinters (NASs). SPs of 154 male and female NASs (100-m personal records [PRs], 9.58–14.00 s) and 7 male ASs (3 unilateral above knee, 3 unilateral below knee, 1 bilateral below knee; 100 m PRs, 11.70–12.70 s) with running specific prostheses (RSPs) were analysed during full-effort sprint starts using instrumented starting blocks that measured the applied forces in 3D. Using the NAS dataset and a combination of factor analysis and multiple regression techniques, we explored the relationship between force characteristics and SP (quantified by normalized average horizontal block power). Start kinetics were subsequently compared between ASs and NASs who were matched based on their absolute 100 m PR and their 100 m PR relative to the world record in their starting class. In NASs, 86% of the variance in SP was shared with five latent factors on which measured parameters related to force application to the rear and front blocks and the respective push-off directions in the sagittal plane of motion were loaded. Mediolateral force application had little influence on SP. The SP of ASs was significantly reduced compared to that of NASs matched on the basis of relative 100-m PR (−33.8%; d = 2.11, p < 0.001), while a non-significant performance reduction was observed when absolute 100-m PRs were used (−17.7%; d = 0.79, p = 0.09). These results are at least partially explained by the fact that force application to the rear block was clearly impaired in the affected legs of ASs.

Highlights

Get ready, set, go! The start of the 100 m final is one of the most anticipated moments of any major athletics championship
The following interpretation was made based on analysis of the factor-loading structure (Fig 3): Variables associated with force application to the rear block and front block in the sagittal plane of motion were highly loaded on factors 1, 4 and 6, respectively (Fig 3), which were considered to represent underlying factors affecting the forces applied to propel the athlete forward out of the blocks
High factor-4 scores were correlated with high peak force application that was concentrated at the end of the push-off phase after a moderate initial rise in force (Fig 4A)

Summary

Introduction

Set, go! The start of the 100 m final is one of the most anticipated moments of any major athletics championship. The start of the 100 m final is one of the most anticipated moments of any major athletics championship. The importance of an athlete’s start performance (SP) is inversely related to the length of the track event. It is very important in the 100 m, less so in the 200 m and potentially most significant in 60 m indoor events. For a typical 100-m race, the start (including reaction time) only takes up about 5% of the PLOS ONE | DOI:10.1371/journal.pone.0166219. For a typical 100-m race, the start (including reaction time) only takes up about 5% of the PLOS ONE | DOI:10.1371/journal.pone.0166219 November 15, 2016

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