Robert Condliffe, 2018
Total Page：16
File Type：pdf, Size：1020Kb
Evaluating and developing the key determinants of push-start performance in bobsleigh Robert James Condliffe BSc (Hons) A doctoral thesis Submitted to the School of Sport at Cardiff Metropolitan University in fulfilment of the requirements for the degree of Doctor of Philosophy August 2018 Director of studies: Dr. Jon L. Oliver Supervisors: Dr. Rhodri S. Lloyd & Professor John Cronin Collaborating establishment: British Bobsleigh COPYRIGHT Attention is drawn to the fact that copyright of this thesis rests with its author. This copy of the thesis has been supplied on the condition that anyone who consults it is understood to recognise that its copyright rests with the author and that no quotation from the thesis and no information derived from it may be published without the prior written consent of the author. © Robert Condliffe, 2018 1 Declaration page This work is being submitted in fulfilment of the requirements for the degree of Doctor of Philosophy within the field of bobsleigh performance testing. I certify that this work has not been previously accepted in substance for any degree and is not being concurrently submitted in candidature for any other degree. I further certify that the whole of this work is the result of my individual efforts, except where otherwise stated. All quotations from books and journals have been acknowledged and a bibliography is appended. I hereby give consent for my thesis, if accepted, to be available for photocopying, and for inter-library loan, and for the title and summary to be made available to outside organisations. I hereby give consent for the University to electronically store, copy or translate the thesis to any approved medium or format for future preservation and accessibility. I hereby give consent that upon deposition in the digital repository, for the thesis to be made accessible to a wide variety of people and institutions, including automated agents and search engines via the World Wide Web. I hereby give consent for the thesis and its metadata to be incorporated into public access catalogues or services, such as national databases of electronic theses. Signed: Candidate: Robert J. Condliffe Date: Monday 6th August 2018 Certificate of supervising tutor in respect of the student’s submitted work. I am satisfied that this work is the result of the above-named student’s own efforts. Signed: Director of studies: Jon L. Oliver Date: Monday 6th August 2018 2 Abstract It is a common belief in bobsleigh that the push-start is a vital aspect of successful performance. Therefore, British Bobsleigh places a heavy emphasis on the use of field-based performance testing to assist with both athlete monitoring and talent identification. There is a general lack of published academic literature in bobsleigh. Thus, limited evidence exists confirming the importance of the push-start, as well as validating the field-based performance tests used by British Bobsleigh. The aim of this thesis was to validate and develop the core principles and scientific underpinnings of squad monitoring and talent identification specific to ‘brake-men’/’brake-women’ push-start performance in bobsleigh. Study 1 examined the relationship between the push-start and finish time across elite bobsleigh competitions for 2-man, 4-man and female event formats, across multiple tracks and over multiple on-ice seasons. The study demonstrated most tracks on the elite bobsleigh circuit to be either push-start dominant or moderately influenced by the push-start (common variance ≥ 10%). Thus, it highlighted the value of evaluating and developing push-start performance in British Bobsleigh athletes. Studies 2 and 3 investigated the current performance testing practices of British Bobsleigh, used in both talent identification and squad monitoring. Study 2 investigated the predictive validity of the ‘evaluation test’ used by British Bobsleigh to assess whether the whole test battery, as well as individual tests included within it relate to the bobsleigh push-start. Although this study confirmed the predictive validity of ‘evaluation test’ total points to assess athletes push-start capabilities (r = -0.86 to -0.94), completion of the entire testing battery proved somewhat unnecessary. This largely manifested from the major finding of this study that confirmed that the roll-bob push test could be used as a reliable (CV = 0.7 to 1.7%) and valid (r = 0.83 to 0.98) predictor of push-start performance. Subsequent attempts to explain push-start performance using only the general performance tests included within the 3 ‘evaluation test’, highlighted the importance of body mass and 30 m sprint time. However, the explained variance in male push-start performance (55 %), highlighted a clear need to examine other performance qualities beyond those in the current British Bobsleigh ‘evaluation test’. Study 3 explored the reliability, discriminative validity and predictive validity of the British Bobsleigh ‘Keiser Squat Test’. The findings of the study confirmed the reliability of the test protocol (CV = 6 to 10 %), as well as reporting very large to near perfect predictive ability for the female push-start (r = -0.86 to -0.96). Despite this, the strength of the prediction was only moderate in male athletes (r = -0.30 to - 0.47) and the test could only distinguish between world class performance (WCP) and national development (ND) male athletes at a moderate load. Subsequently, other performance tests outside the current practices of British Bobsleigh but identified from the winter sliding sport, strength and power diagnostic and sprinting literature were explored. Study 4 investigated the validity of vertical and horizontal jump test metrics, completed under both bilateral and unilateral conditions, to predict push-start performance. The major findings were that horizontally oriented tests (e.g. standing long jump (SLJ)) may represent better push-start predictive ability than vertically oriented tests (e.g. the countermovement jump (CMJ) and ‘Keiser Squat Test’). Also, maximising an athlete’s unilateral facilitation, as well as minimising any between limb asymmetries appears to be beneficial for push-start performance (r = 0.67 to 0.88). Thus, the addition of unilateral SLJ peak horizontal force, bilateral index and asymmetry index to the British Bobsleigh ‘evaluation test’, may help to account for some of the unexplained variance in push-start performance identified in study 2. Study 5 explored the discriminative validity and predictive validity of sprint force-velocity profiling for the bobsleigh push-start. Also, the study investigated the influence of a 16-week pre-season training phase on bobsleigh athlete’s sprint force-velocity mechanical profiles and associated changes in push-start performance. The sprint force-velocity mechanical variables Pmax, relative Pmax, V0 and Vopt were all shown to provide discriminative validity for the bobsleigh push-start. However, of these variables, Pmax demonstrated the strongest correlation with push-start performance (r = 0.80). At a group level, 4 the findings of the study detected training induced improvements in push-start performance, sprint speed and Pmax (absolute & relative), with the largest group-based improvements observed in absolute Pmax. This was reflected with all athletes making worthwhile gains in Pmax, however this did not always translate to improvements in push-start performance on an individual level. Thus, there may be other factors important for push-start performance beyond those measured in this study. To conclude, the push-start has a moderate to large influence on performance at most tracks on the elite bobsleigh circuit. The roll-bob push test provides a reliable and valid measure to quantify the push-start capabilities of bobsleigh athletes. When considering the key underpinning determinants of push-start performance in bobsleigh, this thesis highlighted the importance of body mass, sprinting speed (30 m sprint time), sprinting maximal mechanical power (sprint force-velocity profiling), unilateral horizontal force production (unilateral SLJ) and power production under moderate external loads (‘Keiser Squat Test’). Thus, practitioners working in bobsleigh should consider these key qualities when designing future squad monitoring and talent identification performance testing batteries and designing training programmes. 5 Acknowledgments The completion of this PhD thesis has been the most challenging experience I have completed to date and without the guidance, and encouragement from so many people it would have not been possible. My first thanks go to my director of studies Dr. Jon Oliver for his phenomenal support and guidance throughout the entire project. It has been a privilege to work with such a dedicated supervisor. Also, I would like to thank my other supervisors Dr. Rhodri Lloyd and Professor John Cronin for all the time they gave helping shape the project and reviewing the thesis. It’s been an honour to have such a world class team, who have been a fundamental part of me completing the thesis. Next, I would like to show my gratitude to all the staff and athletes at British Bobsleigh, who made this project possible. Particularly, I would like to thank Gary Anderson, Lauren Forrow and Chris Woolley, who have all been essential advisors throughout the project. Also, big thanks must go to the Sport Wales Institute and all its staff for their continual support during completion of this thesis, as well as throughout my professional career. Finally, and most importantly, thanks go to my Mum and Dad for all their sacrifice and support throughout not only my PhD, but my entire life. Particularly, the many evenings my Mum gave up to proof read chapters of this thesis. She is now an expert in bobsleigh. I would like to dedicate this thesis to my Nephew’s and Niece, Jake, Logan and Esmé Condliffe. 6 Conference Presentations from this Thesis Thesis Embargo At the beginning of the PhD candidature an embargo was placed on this thesis for a period of five years. This was a result of the potential influence the PhD findings could have on the applied practices of British Bobsleigh and therefore the organisation wanted to protect any possible competitive advantage.