title: Changes in running mechanics over 100-m, 200-m and 400-m treadmill sprints.
abstract: Compare alterations in running mechanics during maximal treadmill sprints of different distances.
  
  
  
  Eleven physically active males performed short (100-m), medium (200-m) and long (400-m) running sprints on an instrumented treadmill. Continuous measurement of running kinetics/kinematics and spring-mass characteristics were recorded and values subsequently averaged over every 50-m distance intervals for comparison.
  
  
  
  Compared with the initial 50m, running velocity decreased (P<0.001) by 8±2%, 20±4% and 39±7% at the end of the 100, 200 and 400-m, respectively. All sprint distances (except for step length in the 100-m) induced significantly longer (P<0.05) contact times (+7±4%, +22±8% and +36±13%) and lower step lengths (-1±4%, -5±5% and -41±2%) and frequencies (-6±3%, -13±7% and -22±8%) at the end of the 100-m, 200-m and 400-m, respectively. Larger reductions in ground reaction forces occurred in horizontal versus vertical direction, with greater changes with increasing sprinting distance (P<0.05). Similarly, the magnitude of decrement in vertical stiffness increased with sprint distance (P<0.05), while leg stiffness decreases were smaller and limited to 200-m and 400-m runs. Overall, we observed earlier and larger alterations for the 400-m compared with other distances.
  
  
  
  The magnitude of changes in running velocity and mechanics over short (100-m), medium (200-m) and long (400-m) treadmill sprints increases with sprint distance. The alterations in stride mechanics occur relatively earlier during the 400-m compared with the 100-m and 200-m runs.
authors.affiliation: ISSUL, Institute of Sport Sciences, Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Switzerland.
authors.forename: O
authors.initials: O
authors.lastname: Girard
authors.affiliation: ISSUL, Institute of Sport Sciences, Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Brocherie
authors.affiliation: University of Ljubljana, Faculty of Sport, Ljubljana, Slovenia.
authors.forename: K
authors.initials: K
authors.lastname: Tomazin
authors.affiliation: Aspetar - Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.
authors.forename: A
authors.initials: A
authors.lastname: Farooq
authors.affiliation: Laboratory of Human Motricity, Education Sport and Health (LAMHESS), University of Nice Sophia Antipolis, 261, Route de Grenoble, BP3259, 06205 Nice, Cedex 03, France. Electronic address: jean-benoit.morin@unice.fr.
authors.forename: J-B
authors.initials: JB
authors.lastname: Morin
mesh_terms: D001696:Biomechanical Phenomena; D005080:Exercise Test; D006801:Humans; D008297:Male; D055595:Mechanical Phenomena; D012420:Running / Q000502:physiology*
keywords: Fatigue; Ground reaction forces; Running mechanics; Sprint