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Influence of a slow-start on overall performance and running kinematics during 6-h ultramarathon races

Matta, Guilherme G.; Bossi, Arthur H.; Millet, Guillaume Y.; Lima, Pedro; Lima, Jorge P. de; Hopker, James G.


Guilherme G. Matta

Guillaume Y. Millet

Pedro Lima

Jorge P. de Lima

James G. Hopker


The aim of this study was to describe the pacing during a 6-h ultramarathon (race 1) and to investigate whether a slow-start affects performance, running kinematic changes, ratings of perceived exertion (RPE) and fatigue (ROF) (race 2). After a critical speed test, participants completed two 6-h ultramarathons. Race 1 (n = 16) was self-paced, whereas in race 2 (n = 10), athletes performed the initial 36 min at speeds 18% below the mean speed of the initial 36 min of race 1. In race 1, participants adopted an inverse sigmoid pacing. Contact times increased after 1 h, and flight times decreased after 30 min (all P ≤ .009); stride length reduced after 1 h 30 min (all P = .022), and stride frequency did not change. Despite the lower speeds during the first 10% of race 2, and higher speeds at 50% and 90%, performance remained unchanged (57.5 ± 10.2 vs. 56.3 ± 8.5 km; P = .298). However, RPE and ROF were lowered for most of race 2 duration (all P < .001). For the comparison of kinematic variables between races, data were normalised by absolute running speed at each time point from 1 h onwards. No differences were found for any of the kinematic variables. In conclusion, decreasing initial speed minimises RPE and ROF, but does not necessarily affect performance. In addition, running kinematic changes do not seem to be affected by pacing manipulation.

Journal Article Type Article
Online Publication Date Jun 16, 2019
Publication Date Mar 15, 2020
Deposit Date Aug 16, 2022
Journal European Journal of Sport Science
Print ISSN 1746-1391
Electronic ISSN 1536-7290
Publisher Taylor & Francis
Peer Reviewed Peer Reviewed
Volume 20
Issue 3
Pages 347-356
Keywords Competitive behaviour, effort distribution, ultra-endurance, performance, biomechanics, running gait
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