We compared different approaches to analyze running mechanics alterations during repeated treadmill sprints. Thirteen active male athletes performed five 5-second sprints with 25 seconds of recovery on an instrumented treadmill. This approach allowed continuous measurement of running kinetics/kinematics and calculation of vertical and leg stiffness variables that were subsequently averaged over 3 distinct sections of the 5-second sprint (steps 2–5, 7–10, and 12–15) and for all steps (steps 2–15). Independently from the analyzed section, propulsive power and step frequency decreased with fatigue, while contact time and step length increased (P < .05). Except for step frequency, all mechanical variables varied (P < .05) across sprint sections. The only parameters that highly depend on running velocity (propulsive power and vertical stiffness) showed a significant interaction (P < .05) between the analyzed sections, with smaller magnitude of fatigue-induced change observed for steps 2–5. Considering all steps or only a few steps during early, middle, or late phases of 5-second sprints provides similar mechanical outcomes during repeated treadmill sprinting, although acceleration induces noticeable differences between the sections studied. Furthermore, quantifying mechanical alterations from the early acceleration phase may not be readily detectable, and is not recommended.
Olivier Girard, Franck Brocherie, Jean-Benoit Morin, Francis Degache and Grégoire P. Millet
Simone Ciacci, Rocco Di Michele, Silvia Fantozzi and Franco Merni
Kinematic asymmetry is believed to be associated with elevated risk for muscle injury, but little is known about the links between hamstring injuries and asymmetry of sprinting mechanics.
To evaluate the value of kinematic analysis of sprinting for the detection of injury-related asymmetry in athletes with a history of hamstring strain.
Six sub-elite male sprinters, including two who sustained a hamstring strain injury.
Absolute differences between left and right symmetry indices and symmetry angles were both calculated for ground contact time and selected angular displacements. Measurements were acquired at foot strike, during the stance phase, and at toe-off.
At toe-off, injured athletes exhibited greater knee flexion and less hip extension for the injured extremity compared to the uninjured extremity. Symmetry indices for these variables markedly exceeded an established 15% threshold for clinically relevant asymmetry. Each of the uninjured athletes exhibited a high degree of symmetry for all parameters, with mean values for symmetry indices significantly lower than the 15% threshold (P < 0.05).
Kinematic analysis of sprinting asymmetry appears to be valuable for identification of elevated risk for hamstring injury.
Scott R. Brown, Erin R. Feldman, Matt R. Cross, Eric R. Helms, Bruno Marrier, Pierre Samozino and Jean-Benoît Morin
, Cross MR . Profiling sprint mechanics by leg preference and position in rugby union athletes . Int J Sports Med . 2016 ; 37 : 890 – 897 . PubMed doi:10.1055/s-0042-109067 27410766 10.1055/s-0042-109067 11. Zifchock RA , Davis I , Higginson J , Royer T . The symmetry angle: a novel
Reed D. Gurchiek, Hasthika S. Rupasinghe Arachchige Don, Lasanthi C. R. Pelawa Watagoda, Ryan S. McGinnis, Herman van Werkhoven, Alan R. Needle, Jeffrey M. McBride and Alan T. Arnholt
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Jeffrey D. Simpson, Ludmila Cosio-Lima, Eric M. Scudamore, Eric K. O’Neal, Ethan M. Stewart, Brandon L. Miller, Harish Chander and Adam C. Knight
been shown to induce altered sprint kinematic patterns, 11 , 12 which could result in a negative transfer of sprint mechanics when the WV is removed and diminish sprint performance. 10 Conversely, recent investigations incorporating WV during daily living only have reported improvements in sprint and
Gerda Strutzenberger, Adam Brazil, Timothy Exell, Hans von Lieres und Wilkau, John D. Davies, Steffen Willwacher, Johannes Funken, Ralf Müller, Kai Heinrich, Hermann Schwameder, Wolfgang Potthast and Gareth Irwin
International Society of Biomechanics in Sports. Beijing, China ; August 22–27, 2005 . https://ojs.ub.uni-konstanz.de/cpa/article/view/766/689 . Accessed June 18, 2018. 5. Rabita G , Dorel S , Slawinski J , et al . Sprint mechanics in world-class athletes: a new insight into the limits of human
Johan Cassirame, Hervé Sanchez and Jean-Benoit Morin
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Ryu Nagahara, Mirai Mizutani, Akifumi Matsuo, Hiroaki Kanehisa and Tetsuo Fukunaga
acceleration . Can J Appl Sport Sci . 1984 ; 9 : 42 – 52 . PubMed 6705128 8. Rabita G , Dorel S , Slawinski J , et al . Sprint mechanics in world-class athletes: a new insight into the limits of human locomotion . Scand J Med Sci Sports . 2015 ; 25 : 583 – 594 . PubMed doi:10.1111/sms.12389 10
Gareth N. Sandford, Sian V. Allen, Andrew E. Kilding, Angus Ross and Paul B. Laursen
P , Rabita G , Dorel S , et al . A simple method for measuring power, force, velocity properties, and mechanical effectiveness in sprint running: simple method to compute sprint mechanics . Scand J Med Sci Sports . 2015 ; 26 : 648 – 658 . PubMed ID: 25996964 doi:10.1111/sms.12490 10
Ryu Nagahara, Yohei Takai, Miki Haramura, Mirai Mizutani, Akifumi Matsuo, Hiroaki Kanehisa and Tetsuo Fukunaga
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