A biomechanical analysis of the rugby place kick.

Thesis (MEng)--Stellenbosch University, 2018.ENGLISH ABSTRACT: Compared to other professional sport codes such as soccer, the availability of rugby-based studies rooted in scientific principles is limited. This study forms part of a larger project that aims to broaden the knowledge base surrounding the rugby goal kick. This study set out to achieve the following three objectives: to determine the ideal frequency parameters for the use on kinematic variables during the analysis of the rugby goal kick, testing the validity of possible automatic filtering algorithms applied to the kinematic variables and the identification of a concrete kinematic sequence performed during the rugby goal kicks, by implementing biomechanical analysis principles. In order to achieve this, the three-dimensional kinematic data of twelve elite level kickers were recorded using an 8- camera Vicon system sampling at frequencies of 200 Hz. The testing was conducted at the motion-analysis laboratory at the University of Stellenbosch. The participants were all of national calibre at the time of testing. Each participant performed ten consecutive goal kicks. The testing was conducted on hard rubber floors with the participants wearing running shoes. The effect of the filtering process was visually observed in order to determine the ideal filtering parameters for the kinematic variables. Based on these findings, the validity of several automatic filtering algorithms was tested. It was established that none of the automatic filtering algorithms tested during the study achieved satisfactory results for the use with rugby goal kick kinematic data. The study, however, successfully identified an ideal filtering frequency that could be applied to biomechanical data of such a nature as a rugby goal kick. It furthermore established a kinematic sequence that is performed during the execution of a rugby goal kick.AFRIKAANSE OPSOMMING: In vergelyking met ander professionele sportkodes soos sokker, is daar beperkte beskikbaarheid van wetenskaplik gebasseerde studies rakende rugby. Hierdie studie vorm deel van ‘n groter projek wat daarop gemik is om die kennisbasis rondom die rugby stelskop te verbreed. Die studie het dit ten doel om die volgende drie doelwitte te bereik: om die ideale frekwensie parameters vir gebruik met kinematiese veranderlikes gedurende die analise van die rugby stelskop te bepaal, om die geldigheid van moontlike outomatiese filtrering algoritmes wat toegepas word op die kinematiese veranderlikes te bepaal, en om ‘n vasgestelde kinematiese reeks te bepaal wat tydens die rugby stelskop uitgevoer word, deur die implementering van biomeganiese beginsels. Om die bogenoemde doelwitte te bereik is drie-dimensionele kinematiese data versamel van twaalf professionele rugby stelskoppers. Die data is versamel deur ‘n 8-kamera Vicon sisteem te gebruik wat teen ‘n frekwensie van 200 Hz opneem. Die toetse is uitgevoer in die bewegingslaboratorium van Universiteit van Stelllenbosch. Die deelnemers hat almal op nasionale vlak aan rugby deelgeneem tydens die tydperk waartydens die data versamel is. Elke deelnemer het tien agtereenvolgende stelskoppe uitgevoer. Die toetse is binnenshuis afgeneem. Die laboratorium het ‘n harde rubber vloeroppervvlak en die deelnemers het die skoppe uitgevoer met hardloopskoene. Die invloed van die filtreringsproses op die kinematiese data is visueel waargeneem met die doel om die ideale filtreringsparameters vir kinematiese veranderlikes te bepaal. Na aanleiding van die boegnoemde resultate is daar tot die volgende gevolgtekking gekom: die outomatiese filtreringsalgoritmes wat in hierdie studie getoets is het nie bevredigende resultate vir die kinematiese data van ‘n stelskop gelewer nie. Die studie het egter wel ‘n ideale filtreringsfrekwensie bepaal vir die toepassing op rugby stelskop kinematiese data. Hierdie filtreringsfrekwensie het my in staat gestel om ‘n kinmatiese reeks vir die rugby stelskop te identifiseer