Int J Sports Med 2013; 34(09): 832-840
DOI: 10.1055/s-0032-1329958
Orthopedics & Biomechanics
© Georg Thieme Verlag KG Stuttgart · New York

Changes in Running Mechanics and Spring-Mass Behaviour during a 5-km Time Trial

O. Girard
1   Research and Education Centre, ASPETAR – Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
,
G. P. Millet
2   ISSUL, Institute of Sport Sciences, Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
,
J. Slawinski
3   CeRSM (EA 2931), Faculty of Sport Sciences, University of Paris Ouest Nanterre la Defense, Nanterre, France
,
S. Racinais
1   Research and Education Centre, ASPETAR – Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
,
J. P. Micallef
3   CeRSM (EA 2931), Faculty of Sport Sciences, University of Paris Ouest Nanterre la Defense, Nanterre, France
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accepted after revision 05. Oktober 2012

Publikationsdatum:
02. April 2013 (online)

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Abstract

Research into the biomechanical manifestation of fatigue during exhaustive runs is increasingly popular but additional understanding of the adaptation of the spring-mass behaviour during the course of strenuous, self-paced exercises continues to be a challenge in order to develop optimized training and injury prevention programs. This study investigated continuous changes in running mechanics and spring-mass behaviour during a 5-km run. 12 competitive triathletes performed a 5-km running time trial (mean performance: ̴17 min 30 s) on a 200 m indoor track. Vertical and anterior-posterior ground reaction forces were measured every 200 m by a 5-m long force platform system, and used to determine spring-mass model characteristics. After a fast start, running velocity progressively decreased (− 11.6%; P<0.001) in the middle part of the race before an end spurt in the final 400–600 m. Stride length (− 7.4%; P<0.001) and frequency (− 4.1%; P=0.001) decreased over the 25 laps, while contact time (+ 8.9%; P<0.001) and total stride duration (+ 4.1%; P<0.001) progressively lengthened. Peak vertical forces (− 2.0%; P<0.01) and leg compression (− 4.3%; P<0.05), but not centre of mass vertical displacement (+ 3.2%; P>0.05), decreased with time. As a result, vertical stiffness decreased (− 6.0%; P<0.001) during the run, whereas leg stiffness changes were not significant (+ 1.3%; P>0.05). Spring-mass behaviour progressively changes during a 5-km time trial towards deteriorated vertical stiffness, which alters impact and force production characteristics.