title: Sprint Acceleration Mechanics: The Major Role of Hamstrings in Horizontal Force Production.
abstract: Recent literature supports the importance of horizontal ground reaction force (GRF) production for sprint acceleration performance. Modeling and clinical studies have shown that the hip extensors are very likely contributors to sprint acceleration performance. We experimentally tested the role of the hip extensors in horizontal GRF production during short, maximal, treadmill sprint accelerations. Torque capabilities of the knee and hip extensors and flexors were assessed using an isokinetic dynamometer in 14 males familiar with sprint running. Then, during 6-s sprints on an instrumented motorized treadmill, horizontal and vertical GRF were synchronized with electromyographic (EMG) activity of the vastus lateralis, rectus femoris, biceps femoris, and gluteus maximus averaged over the first half of support, entire support, entire swing and end-of-swing phases. No significant correlations were found between isokinetic or EMG variables and horizontal GRF. Multiple linear regression analysis showed a significant relationship (P = 0.024) between horizontal GRF and the combination of biceps femoris EMG activity during the end of the swing and the knee flexors eccentric peak torque. In conclusion, subjects who produced the greatest amount of horizontal force were both able to highly activate their hamstring muscles just before ground contact and present high eccentric hamstring peak torque capability.
authors.affiliation: Laboratory of Human Motricity, Education Sport and Health (EA6312), Faculty of Sport Sciences, University of Nice Sophia Antipolis Nice, France.
authors.forename: Jean-Benoît
authors.initials: JB
authors.lastname: Morin
authors.affiliation: Laboratory Culture Sport Health Society (EA 4660), University of Franche-Comté Besançon, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Gimenez
authors.affiliation: Laboratory of Exercise Physiology (EA4338), University of LyonSaint-Etienne, France; Sports Medicine Unit, Department of Clinical and Exercise Physiology, Faculty of Medicine, University Hospital of Saint-EtienneSaint-Etienne, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Edouard
authors.affiliation: Laboratory of Exercise Physiology (EA4338), University of Lyon Saint-Etienne, France.
authors.forename: Pierrick
authors.initials: P
authors.lastname: Arnal
authors.affiliation: Faculty of Physical Sciences and Sport, Catholic University of San Antonio Murcia, Spain.
authors.forename: Pedro
authors.initials: P
authors.lastname: Jiménez-Reyes
authors.affiliation: Laboratory of Exercise Physiology (EA4338), University Savoie Mont Blanc Le Bourget-du-Lac, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Samozino
authors.affiliation: School of Sport and Recreation, Sports Performance Research Institute New Zealand, Auckland University of Technology Auckland, New Zealand.
authors.forename: Matt
authors.initials: M
authors.lastname: Brughelli
authors.affiliation: Department of Physical Therapy, ZENTRUM Rehab and Performance Center Barañain, Spain.
authors.forename: Jurdan
authors.initials: J
authors.lastname: Mendiguchia
keywords: isokinetics; muscle; neuromuscular; performance; sprint kinetics; surface electromyography