Electromechanical delay of the harmstrings and its significance for the analyse and optimisation of sprint running

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Bibliographic Details
Title translated into German:Elektromechanische Verzögerung in der hinteren Oberschenkelmuskulatur und ihre Signifikanz für die Analyse und Optimierung des Sprintlaufs
Author:Jöllenbeck, Thomas
Published in:Sport Kinetics '97 : theories of human motor performance and their reflections in practice. Vol. 1: Lectures. Fifth International Scientific Conference of the International Association of Sport Kinetics common with the Section "Sportmotorik" of the German Association for Sport Science (dvs) and the Institute of Sport Science of Otto-von-Guericke-University of Magdeburg. Magdeburg, 3-6 September, 1997
Published:Hamburg: Czwalina (Verlag), 1998, S. 90-94, Lit.
Editor:Deutsche Vereinigung für Sportwissenschaft
Research institution:Universität Magdeburg / Institut für Sportwissenschaft; International Association of Sport Kinetics; Deutsche Vereinigung für Sportwissenschaft / Sektion Sportmotorik
Format: Publications (Database SPOLIT)
Publication Type: Compilation article
Media type: Print resource
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Identification number:PU200302000371


Only the exact knowledge of the electromechanical delay (EMD) of a muscle, the phase-shift between the onset of EMG and the onset of force provides important conclusions about the mechanical effectiveness of a muscle becoming evident via the corresponding EMG. By means of an underlying, hypothetical EMD of 40 ms for all investigated muscles TIDOW/WIEMANN (1994) could demonstrate that the horizontal acceleration in sprint running was not mainly generated by the knee extensors but to a predominant proportion by the hip extensors. However, in the past publications reported EMD values of the knee extensor and hip flexor muscles ranging between 32 ms and 118 ms. Under consideration of such EMD values the results of TIDOW/WIEMANN (1994) could be brought into question again. In order to shed light upon this question 68 subjects performed three explosive maximal iso-metric voluntary contractions (MIVC) with their hamstrings. The established EMD values for the before not examined hamstrings were only 24 ms +/- 7 ms. Hence the results of TIDOW/WIEMANN (1994) become even more significant concerning the importance of the hamstrings for sprint running. Underlying EMD values of 24 ms for the examined muscles the mechanical effectiveness of the knee extensors seems to be restricted to the front support, whereas the hip extensors generate mechanical energy throughout the complete support phase. The submitted results underline the importance of further investigation of the EMD in order to promote the analysis and optimisation of sprint running and suggest to redefine the EMD for all muscles involved in sprint running. Verf.-Referat