Doug Thake

Multivariate analyses of individual variation in soccer skill as a tool for talent identification and development: utilising evolutionary theory in sports science

ABSTRACT The development of a comprehensive protocol for quantifying soccer-specific skill could markedly improve both talent identification and development. Surprisingly, most protocols for talent identification in soccer still focus on the more generic athletic attributes of team sports, such as speed, strength, agility and endurance, rather than on a player’s technical skills. We used a multivariate methodology borrowed from evolutionary analyses of adaptation to develop our quantitative assessment of individual soccer-specific skill. We tested the performance of 40 individual academy-level players in eight different soccer-specific tasks across an age range of 13–18 years old. We first quantified the repeatability of each skill performance then explored the effects of age on soccer-specific skill, correlations between each of the pairs of skill tasks independent of age, and finally developed an individual metric of overall skill performance that could be easily used by coaches. All of our measured traits were highly repeatable when assessed over a short period and we found that an individual’s overall skill – as well as their performance in their best task – was strongly positively correlated with age. Most importantly, our study established a simple but comprehensive methodology for assessing skill performance in soccer players, thus allowing coaches to rapidly assess the relative abilities of their players, identify promising youths and work on eliminating skill deficits in players.

The effect of carbohydrate ingestion on cardiorespiratory responses to inclined walking during normobaric hypoxia

The Rotor (ROT) is a cycle crank configuration that allows the pedals to move independently in an attempt to eliminate the “dead spots”, where torque output is minimal. Delta efficiency has been found to be significantly improved during an incremental test when using ROT in a group of untrained cyclists (Santalla et al., 2002: Medicine and Science in Sports and Exercise, 34, 1854-1858). However, no study has investigated whether ROT affects cycling performance directly. Therefore, the purpose of this study was to investigate the effect of ROT on time-trial cycling performance. Following institutional ethics approval, 12 competitive male cyclists (Age mean 34.6, s = 7.1 years, Mass mean 75.9, s = 7.8 kg, max mean 4.5, s = 0.3 L•min-1, Wmax mean 363, s = 37.7 W) provided written informed consent to participate. All subjects completed two 40.23-km time-trials on a Kingcycle ergometer in each of two conditions, i) using conventional bicycle cranks (CON) and ii) using the Rotor system (ROT). Cyclists trained for 6-weeks prior to the experimental trials as either habitual ROT users or habitual CON users. Power output, speed, heart rate, , RER and gross efficiency were measured for the duration of each time-trial. A two-way repeated measures ANOVA (pedalling system used during the test [CON, ROT] x habitual pedalling system [CON, ROT]) was performed to determine if there was a significant condition effect on the following variables: power output, speed, heart rate, , RER and gross efficiency. Statistical significance was set at P 0.05). Indeed, no effect due to the pedalling system used during tests was found for any of the measured variables (P > 0.05). Furthermore, there was no interaction effect between the two factors for any of the measured variables (P > 0.05). However, there were marked differences between conditions for some individuals. For example, power output was ~11% higher during the CON trial vs. the ROT trial for one subject but ~12% lower in another. These results suggest that the Rotor crank system does not impact on time-trial cycling performance. However, marked differences were observed between CON and ROT in some individuals, suggesting that ROT may be beneficial in some instances.Sport psychology researchers have long been interested in identifying the psychological qualities of peak athletic performance (see Krane & Williams, 2006: In Applied sport psychology: Personal growth for peak performance, edited by J. M. Williams. New York: MacGraw-Hill). Several recall studies, involving Olympic and World Champions, have provided insights into how athletes develop these qualities (e.g. Durand-Bush & Salmela, 2002: Journal of Applied Sport Psychology, 14, 154–171). However, there has been limited research investigating the psychological qualities perceived essential during specific stages of athlete development. Furthermore, the existent studies exploring ideal psychological qualities have tended to adopt the perspective of the athlete, while the perceptions of significant others (e.g. the coach) involved in athlete development, have often been overlooked. The importance of obtaining multiple perspectives is reinforced by investigations that have reported inconsistencies between coaches’ and athletes’ perceptions (e.g. Vargas-Tonsing, Myers, & Feltz, 2004: The Sport Psychologist, 18, 397–414). Therefore, the aim of the present research was to examine the perceived ideal psychological qualities deemed relevant to elite pathway under-16 rugby, and compare perceptions shared by under-16 players with the views expressed by their coaches and players who recently progressed from this level (under-18). Eight focus group interviews were conducted with under-16 (n¼28) and under-18 (n¼10) male rugby players, and coaches (n¼7). Each group consisted of 4–10 participants and lasted between 45 and 60 minutes. 11 first-order and 35 second-order themes emerged from content analysis of the data. Under-16 players generated the broadest set of qualities, and emphasised the importance of determination, self-confidence, and effective regulation of performance state. Under-18 players and coaches were more focused in their consideration of the desired qualities in under-16 district level rugby players. For under-18 players, themes of note included successful adaptation to novel environments and taking responsibility for oneself. Themes perceived critical by coaches included self-aware learning through honest selfappraisal and successful application of coach information into physical practice and performance. Altogether, the themes support previous research into the psychological characteristics of elite competitors, and contribute to our understanding of their manifestation in young talented team sport athletes. Moreover, this study extends previous research through the inclusion of the coaches’ perspectives of the ideal psychological qualities in their athletes. The information gathered should provide insight into the development of mental skills training programmes for this population.Many (or even most) fundamental cognitive operations that are driven by stimuli in our environment occur implicitly and generate knowledge that is ‘‘always ahead of the capability of its possessor to explicate’’ (Reber, 1993: Implicit learning and tacit knowledge: An essay on the cognitive unconscious. Oxford: Oxford University Press). The study of implicit processes in sport has developed primarily within the field of attention and motor learning (for a review see Masters & Maxwell, 2004. In Skill acquisition in sport: research, theory and practice, edited by A. M. Williams & N. J. Hodges. London: Routledge). Helmholtz (1867: Treatise on physiological optics. New York: Dover) proposed that perception relies upon a process of ‘‘unconscious inference’’ in which knowledge is encoded automatically without awareness, but it is only recently that researchers have begun to explore more directly the relationship between perception and performance in different sport environments and to realise that our perceptions of the environment can be dramatically influenced by cognitive processes of which we are unaware (see, for example, Masters, van der Kamp, & Jackson, 2007: Psychological Science, 18, 222–223). The purpose of this symposium is to present recent research that explores the influence of implicit processes on perception and performance in a variety of different sport contexts. Rich Masters (Institute of Human Performance, The University of Hong Kong) will provide a brief overview of the background to the work and will show how the different presentations are integrated within the theme of implicit cognition in sport. Rob Jackson (School of Sport & Education, Brunel University) will discuss the different ways in which expert performers and novice performers (in soccer) are influenced by deceptive movements that are designed to cause (mis)perception. John van der Kamp (Research Institute Move, VU University) will discuss whether goalkeepers can influence the perceptions (and perhaps the actions) of penalty-takers by imitating visual illusions. Jamie Poolton (Institute of Human Performance, The University of Hong Kong) will present a series of studies that show reputation can have a dramatic effect on perceptions of the size of an opponent. Finally, Rich Masters will present a study, which suggests that psychological pressure amplifies perceptions of the size and weight of objects or implements in sport, but only in those performers who are successful rather than unsuccessful under pressure.

An incremental step test for use in laboratory and field based hypoxia

The Rotor (ROT) is a cycle crank configuration that allows the pedals to move independently in an attempt to eliminate the “dead spots”, where torque output is minimal. Delta efficiency has been found to be significantly improved during an incremental test when using ROT in a group of untrained cyclists (Santalla et al., 2002: Medicine and Science in Sports and Exercise, 34, 1854-1858). However, no study has investigated whether ROT affects cycling performance directly. Therefore, the purpose of this study was to investigate the effect of ROT on time-trial cycling performance. Following institutional ethics approval, 12 competitive male cyclists (Age mean 34.6, s = 7.1 years, Mass mean 75.9, s = 7.8 kg, max mean 4.5, s = 0.3 L•min-1, Wmax mean 363, s = 37.7 W) provided written informed consent to participate. All subjects completed two 40.23-km time-trials on a Kingcycle ergometer in each of two conditions, i) using conventional bicycle cranks (CON) and ii) using the Rotor system (ROT). Cyclists trained for 6-weeks prior to the experimental trials as either habitual ROT users or habitual CON users. Power output, speed, heart rate, , RER and gross efficiency were measured for the duration of each time-trial. A two-way repeated measures ANOVA (pedalling system used during the test [CON, ROT] x habitual pedalling system [CON, ROT]) was performed to determine if there was a significant condition effect on the following variables: power output, speed, heart rate, , RER and gross efficiency. Statistical significance was set at P 0.05). Indeed, no effect due to the pedalling system used during tests was found for any of the measured variables (P > 0.05). Furthermore, there was no interaction effect between the two factors for any of the measured variables (P > 0.05). However, there were marked differences between conditions for some individuals. For example, power output was ~11% higher during the CON trial vs. the ROT trial for one subject but ~12% lower in another. These results suggest that the Rotor crank system does not impact on time-trial cycling performance. However, marked differences were observed between CON and ROT in some individuals, suggesting that ROT may be beneficial in some instances.Sport psychology researchers have long been interested in identifying the psychological qualities of peak athletic performance (see Krane & Williams, 2006: In Applied sport psychology: Personal growth for peak performance, edited by J. M. Williams. New York: MacGraw-Hill). Several recall studies, involving Olympic and World Champions, have provided insights into how athletes develop these qualities (e.g. Durand-Bush & Salmela, 2002: Journal of Applied Sport Psychology, 14, 154–171). However, there has been limited research investigating the psychological qualities perceived essential during specific stages of athlete development. Furthermore, the existent studies exploring ideal psychological qualities have tended to adopt the perspective of the athlete, while the perceptions of significant others (e.g. the coach) involved in athlete development, have often been overlooked. The importance of obtaining multiple perspectives is reinforced by investigations that have reported inconsistencies between coaches’ and athletes’ perceptions (e.g. Vargas-Tonsing, Myers, & Feltz, 2004: The Sport Psychologist, 18, 397–414). Therefore, the aim of the present research was to examine the perceived ideal psychological qualities deemed relevant to elite pathway under-16 rugby, and compare perceptions shared by under-16 players with the views expressed by their coaches and players who recently progressed from this level (under-18). Eight focus group interviews were conducted with under-16 (n¼28) and under-18 (n¼10) male rugby players, and coaches (n¼7). Each group consisted of 4–10 participants and lasted between 45 and 60 minutes. 11 first-order and 35 second-order themes emerged from content analysis of the data. Under-16 players generated the broadest set of qualities, and emphasised the importance of determination, self-confidence, and effective regulation of performance state. Under-18 players and coaches were more focused in their consideration of the desired qualities in under-16 district level rugby players. For under-18 players, themes of note included successful adaptation to novel environments and taking responsibility for oneself. Themes perceived critical by coaches included self-aware learning through honest selfappraisal and successful application of coach information into physical practice and performance. Altogether, the themes support previous research into the psychological characteristics of elite competitors, and contribute to our understanding of their manifestation in young talented team sport athletes. Moreover, this study extends previous research through the inclusion of the coaches’ perspectives of the ideal psychological qualities in their athletes. The information gathered should provide insight into the development of mental skills training programmes for this population.Many (or even most) fundamental cognitive operations that are driven by stimuli in our environment occur implicitly and generate knowledge that is ‘‘always ahead of the capability of its possessor to explicate’’ (Reber, 1993: Implicit learning and tacit knowledge: An essay on the cognitive unconscious. Oxford: Oxford University Press). The study of implicit processes in sport has developed primarily within the field of attention and motor learning (for a review see Masters & Maxwell, 2004. In Skill acquisition in sport: research, theory and practice, edited by A. M. Williams & N. J. Hodges. London: Routledge). Helmholtz (1867: Treatise on physiological optics. New York: Dover) proposed that perception relies upon a process of ‘‘unconscious inference’’ in which knowledge is encoded automatically without awareness, but it is only recently that researchers have begun to explore more directly the relationship between perception and performance in different sport environments and to realise that our perceptions of the environment can be dramatically influenced by cognitive processes of which we are unaware (see, for example, Masters, van der Kamp, & Jackson, 2007: Psychological Science, 18, 222–223). The purpose of this symposium is to present recent research that explores the influence of implicit processes on perception and performance in a variety of different sport contexts. Rich Masters (Institute of Human Performance, The University of Hong Kong) will provide a brief overview of the background to the work and will show how the different presentations are integrated within the theme of implicit cognition in sport. Rob Jackson (School of Sport & Education, Brunel University) will discuss the different ways in which expert performers and novice performers (in soccer) are influenced by deceptive movements that are designed to cause (mis)perception. John van der Kamp (Research Institute Move, VU University) will discuss whether goalkeepers can influence the perceptions (and perhaps the actions) of penalty-takers by imitating visual illusions. Jamie Poolton (Institute of Human Performance, The University of Hong Kong) will present a series of studies that show reputation can have a dramatic effect on perceptions of the size of an opponent. Finally, Rich Masters will present a study, which suggests that psychological pressure amplifies perceptions of the size and weight of objects or implements in sport, but only in those performers who are successful rather than unsuccessful under pressure.

Neutrophil activity and uphill walking in acute hypoxia equivalent to 3000 m

The Relative Age Effect (RAE) is a phenomenon that suggests that athletes at elite level are more likely to be born in the first 3 months after the eligibility cut-off date for a particular age group in sports. For example, with sports, such as football, which generally use a cut-off date of January 1st (any player born in 1998 is eligible to play at Under 15 level for the season beginning in 2013) players who compete at elite level of under-age sport are substantially more likely to be born in the months of January, February and March. Similarly if the cut-off date is July 1st then the likelihood of elite players being born in July, August and September increases dramatically. It has been shown that a change in eligibility cut-off date only serves to adjust the RAE to the months following the new date (Butler D; Butler R & Sherman M).Recently, it has been suggested that movement variability –particularly coordination variability – can be functional in reducing the risk of injury. Pollard et al. (2005: Journal of Applied Biomechanics, 21, 143 – 152) reported that females demonstrate lower coordination variability than males during performance of an unanticipated cutting movement. Furthermore, a history of lower extremity injury has been shown to effect lower extremity coordination variability during running (Heiderscheit et al., 2002: Journal of Applied Biomechanics, 18, 110 – 121). Therefore, the purpose of this study was to evaluate both the effect of gender and history of ACL injury on lower extremity joint coupling variability during performance of an unanticipated cutting technique. With approval from the University’s ethics committee, 8 female basketball players (age 21.6 +1.41 years, height 1.70 +0.08 m, mass 64.6 +7.3 kg), 8 male basketball players (age 22.9+ 2.95, height 1.90 +0.19 m, mass 77.1 + 11.7 kg) and 6 additional female basketball players with a history of unilateral ACL reconstruction (ACLr; age Abstracts S21 29.4 + 8.92 years, height 1.70 +0.05 m, mass 67.5 + 9.62 kg) provided written, informed consent. During performance of seven unanticipated cutting tasks, three-dimensional joint and segment kinematics were recorded using an eight digital-camera motion capture system (Motion Analysis Corp.,Santa Rosa, CA, USA) sampling at 240 Hz. Between groups differences in joint and segment coupling variability were evaluated with between group ANOVAs. Furthermore, the explained variance (Z2) for each joint coupling was calculated to demonstrate the magnitude of differences between the three groups. In support of Pollard et al. (2005), females demonstrated reduced variability in two joint couplings (hip abduction-adduction/knee rotation variability (P ¼ 0.03, Z2¼ 0.55) and hip rotation/knee abduction-adduction (P ¼ 0.01, Z2 ¼ 0.61). These differences may be associated with female increased risk of ACL injury (Pollard et al., 2005). Female athletes’ movement patterns may not be variable enough to adapt to environmental constraints during basketball play resulting in ACL injuries. Males displayed the most flexible movements in all couplings. Interestingly, the ACLr group demonstrated variability that was greater than females but less than males in the majority of couplings. This study warrants further investigation into the effects of gender and ACL reconstruction on lower extremity joint coordination variability, and its implications to female injury.Annual Conference of the British Association of Sport and Exercise Sciences 2007

Graded exercise testing for uphill walking studies

Soccer instep kick kinematics has been examined in the literature through 2D analysis and more recently 3D analysis (Levanon and Dapena, 1998: Medicine and Science in Sports and Exercise, 30, 917–927). The importance of ball approach prior to kick execution has been recognised in other sports such as rugby (Jackson and Baker, 2001: The Sport Psychologist, 15, 48–65). However, there is limited research on the relationship between ball approach, shot accuracy and kick kinematics in soccer. The objective of this case study was to establish the effect of altering the ball approach, on kick kinematics and shot accuracy, when performing instep penalty kicks.Annual Conference of the British Association of Sport and Exercise Sciences Liverpool, 7th – 9th September 2004 PART I. BIOMECHANICS 20. Parameter determination for a torque-driven model of springboard diving takeoff P.W. Kong, M.R. Yeadon and M.A. King School of Sport and Exercise Sciences, Loughborough University, Ashby Road, Loughborough, LE11 3TU In order to develop a planar computer simulation model of a springboard and a 8-segment diver suitable for investigating diving takeoffs (Fig. 1), it is necessary to determine subject-specific model parameters. These include: 1) springboard, 2) segmental inertia, 3) strength, 4) wobbling mass, and 5) foot-springboard interface parameters. The aim of this study was to determine such parameters either directly from measurements or indirectly using an angle-driven model. Subject-specific parameters were determined from an elite female diver who provided informed consent. Testing procedures were approved by the University Ethical Advisory Committee. The vertical behaviour of the springboard was modelled as a linear mass-spring system with no damping and with stiffness as a linear function of foot placement. The stiffness and effective board mass were measured using a dynamic board loading method (Miller and Jones, 1999: Research Quarterly for Exercise and Sport, 70, 395–400). The horizontal deflection was a quadratic function of the vertical deflection and the board angle was a linear function of the vertical deflection. Body segmental inertias were calculated from 95 anthropometric measurements of the diver using a mathematical model of the human body (Yeadon, 1990: Journal of Biomechanics, 23, 67–74). To ensure that the torque generators produced realistic joint torques, maximum isometric and isovelocity torques of the diver were obtained using an isokinetic dynamometer. Movements measured included flexion and extension of shoulder, hip, knee and ankle. A 10parameter fit was used to express torque as a function of joint angle and angular velocity. Wobbling masses were included in the shank, thigh and trunk segments to model the movement of soft tissues during impact. The wobbling mass inertias were calculated from body composition and density reported in the literature and scaled to the diver. Each wobbling mass was attached to the body segment through two pairs of non-linear damped springs. Initial estimates of stiffness and damping were chosen so as to produce appropriate displacement and oscillation frequency. The elastic properties of the foot-springboard interface were represented by three pairs of spring-dampers acting on the heel, ball and toes. The stiffness and damping of these elastic elements, along with the refined estimation ofwobblingmass parameters and springboard stiffness, were determined using an angle-driven model. This was achieved by driving the model with joint angle time histories obtained from 200 Hz video recordings of diving performance from a one-metre springboard and minimising the difference in orientation and linear and angular momentum between simulation and performance using the Simulated Annealing optimisation algorithm (Corana et al., 1987: ACM Transactions on Mathematical Software, 13, 262–280). Four dives with minimum and maximum angular momentum in the Fig. 1. Simulation model of a springboard and a diver. Journal of Sports Sciences, 2005, 23, 93–223 Journal of Sports Sciences ISSN 0264-0414 print/ISSN 1466-447X online # 2005 Taylor & Francis Group Ltd DOI: 10.1080/02640410512331334413 forward and reverse groups were used to obtain a common set of parameters. The mean difference between simulation and performance was 8.3%. This paper described how subject-specific parameters could be measured experimentally or determined indirectly using an angle-driven model. These model parameters will then be used in a torque-driven model which, after satisfactory evaluation, will be used to investigate diving takeoff techniques and to optimise performance. Acknowledgment: This study was supported by the International Society of Biomechanics. 21. Strategies for maximum velocity movements in relation to reaction time and performance