Analysis of Direct Shots at Goal from Free Kicks in Elite Women's Football
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Please do not remove this page Analysis of direct shots at goal from free kicks in elite women's football Alcock, Alison Marie https://researchportal.scu.edu.au/discovery/delivery/61SCU_INST:ResearchRepository/1267138160002368?l#1375425850002368 Alcock, A. M. (2010). Analysis of direct shots at goal from free kicks in elite women’s football [Southern Cross University]. https://researchportal.scu.edu.au/discovery/fulldisplay/alma991012821687802368/61SCU_INST:Research Repository Southern Cross University Research Portal: https://researchportal.scu.edu.au/discovery/search?vid=61SCU_INST:ResearchRepository [email protected] Open Copyright A Alcock 2010 Downloaded On 2021/09/29 08:27:42 +1000 Please do not remove this page Analysis of Direct Shots at Goal from Free Kicks in Elite Women's Football by Alison Marie Alcock BSc (Hons) - Sports Science (Biomechanics) Liverpool John Moores University A thesis submitted for the degree Doctor of Philosophy November 2010 School of Health and Human Sciences Southern Cross University, Lismore, Australia Declaration I certify that the work presented in this thesis is, to the best of my knowledge and belief, original, except as acknowledged in the text, and that the material has not been submitted, either in whole or in part, for a degree at this or any other university. I acknowledge that I have read and understood the University's rules, requirements, procedures and policy relating to my higher degree research award and to my thesis. I certify that I have complied with the rules, requirements, procedures and policy of the University (as they may be from time to time). Miss Alison Marie Alcock Signature: Date: ii Supervisor's Declaration I certify that this thesis entitled "Analysis of Direct Shots at Goal from Free Kicks in Elite Women's Football," submitted by Alison Marie Alcock in fulfilment of the degree of Doctor of Philosophy is ready for examination. Associate Professor Wendy Gilleard Signature: Date: iii Abstract In elite football, approximately one third of all goals originate from set plays, and of those direct free kicks are the most effective for scoring goals. The purpose of this study was to determine the key attributes of successful direct free kicks in elite women's football and the mechanisms involved in expert performance of the skill. A method was developed that could reliably locate a football on a pitch within 0.24 m using television coverage and the official pitch markings, and then applied to all direct shots at goal from free kicks in the 2007 women's World Cup. All seven shots that resulted in a goal were taken from within 27 m of the goal, entered the goal within approximately 1 m of the goalpost, and had a significantly faster flight time than those that were unsuccessful. All shots directed towards the bottom and centre of the goal resulted in straightforward saves for the goalkeeper. This information can facilitate decisions on where direct shots from free kicks should be practised from in training and when a direct shot should or should not be attempted in competition. The attributes of a successful direct free kick were used to set up a replica laboratory-based free kick that would likely score in elite women's competition. Fifteen international female footballers performed simulated free kicks (curve kicks) and instep kicks at goal from the same location. Ball flight characteristics and full-body three-dimensional kinematics were analysed. Curve kicks had significantly greater lateral and vertical launch angles, increased sidespin and spin about the antero-posterior axis, and more spin about the vertical axis compared with instep kicks. Regression models demonstrated how carefully controlled the flight characteristics must be to hit the target with launch angles constrained to within 3°. To achieve the curved ball trajectory, players should take a wide approach angle to the ball, point the support foot to the right of the intended target, swing the kicking limb across the face of the target, and impact the ball with the foot moving upwards and in an abducted position. In both kick types, peak knee angular velocity and ankle linear velocity occurred at ball impact providing biomechanical evidence to support the common coaching recommendation of kicking through the ball. These findings could assist coaches by focusing their attention to the fundamental coaching points necessary to achieve a curved trajectory of the ball when observing and correcting technique. iv List of Publications I warrant that I have obtained, where necessary, permission from the copyright owners to use any third-party copyright material reproduced in the thesis (e.g. questionnaires, artwork, unpublished letters), or to use any of my own published work (e.g. journal articles) in which the copyright is held by another party (e.g. publisher, co-author). Journal Publications Alcock, A, Hunter, A & Brown, N. (2009). Determination of football pitch locations from video footage and official pitch markings. Sports Biomechanics, 8, 129-140. Alcock, A. (2010). Analysis of shots at goal direct from free kicks in the women's football World Cup 2007. European Journal of Sport Science, 10,279-284. Alcock, A., Gilleard, W., Baker, J., Brown., N. A T., & Hunter, A, (in press). Initial ball flight characteristics of curve and instep kicks in elite women's football. Journal of Applied Biomechanics. Alcock, A, Gilleard, W., Hunter, A, Baker, J.,& Brown, N. A T., (submitted). Curve and instep kick kinematics in elite female footballers. Manuscript submitted for publication. List of Conference Presentations Alcock, A, Hunter, A & Brown, N. A T. (2008). Analysis of the direct free kicks in the 2007 Women's World Cup. Presented at The First World Conference on Science and Soccer. Liverpool, UK. May 2008. Alcock, A. (2009). Analysis of free kicks taken directly at goal in elite women's football. Presented at the Sports Medicine Australia ACT Branch Conference, Batemans Bay, Australia. January 2009. Alcock, A, Brown, N., Baker, J., Gilleard, W. & Hunter, A (2009). Comparison of straight and curve kick impact kinematics in elite female football players. v Presented at the 7th Australasian Biomechanics Conference, Gold Coast, Australia. November 2009. Alcock, A., Gilleard, W., Baker, J. & Brown, N. A. T. (2010). Flight characteristics of successful direct free kicks in elite women's football. Presented at the 2nd World Conference on Science and Soccer, Port Elizabeth, South Africa. June 2010. vi Statement of contribution of others Chapter 3 - Determination of Football Pitch Locations from Video Footage and Official Pitch Markings. Adam Hunter assisted with data collection and analysed the location of 18 balls on the pitch to determine the inter-reliability of the curve-fitting method which was developed. It was Nicholas Brown's idea to perform a sensitivity analysis on the data to determine how potential inaccuracies in pitch markings affected the reconstructed ball coordinates and he also provided advice on the writing phase of this chapter. Chapter 6 - Initial ball flight characteristics of curve and instep kicks in elite women's football, and Chapter 7 - Comparison of curve and instep kick kinematics in elite female footballers Wendy Gilleard, Nicholas Brown and John Baker provided advice on the research design and writing phase of these studies. The customised software used to calculate the ball centre was written by Adam Hunter. vii Acknowledgements I wish to acknowledge the Southern Cross University Division of Research, Southern Cross University School of Health and Human Sciences and the Australian Institute of Sport for their financial support in funding the projects undertaken to form this thesis, and for attendance at international conferences. In addition I would like to acknowledge the use of the University of Western Australia BodyBuilder model in the analysis of data. To my supervisors, Associate Professor Wendy Gilleard, Professor Keith Lyons, Mr. John Baker, Dr. Nick Brown, and Professor John Hammond, thanks for the expert advice, words of wisdom and valuable time you have spent guiding me through this journey. You have both challenged me and encouraged me along the way, you have influenced the scientist in me in many ways and for that I will always be grateful. Special thanks to Tom Sermanni and Robbie Hooker for their expert opinions on what contributes to performance of the different kick types in elite women's football, and to all the athletes who willingly gave up their time to participate. This thesis would not exist without your help and cooperation. To the staff from the Australian Institute of Sport who selflessly gave up their time to assist with equipment set-up and data collection, and for sharing your knowledge. Thank you all for your time, whether it was a lot or a little, I couldn't have done it without you. Finally, thanks to my family and friends for the love and support you have given me in everything I have ever decided to do. viii Table of Contents ANALYSIS OF DIRECT SHOTS AT GOAL FROM FREE KICKS IN ELITE WOMEN'S FOOTBALL. ............................ I DECLARATION .................................................................................................................................................... 11 SUPERVISOR'S DECLARATION ............................................................................................................................... III ABSTRACT .......................................................................................................................................................