Christopher A. Barnes

Factors associated with increased propensity for hamstring injury in English Premier League soccer players.

The aim of this study was to concurrently model the influence of a number of physical and performance parameters on subsequent incidence of hamstring injury in a squad of English Premier League soccer players. Thirty six healthy, male, elite, professional soccer players (age 22.6+/-5.2 years, height 1.81+/-0.08 m, mass 75.8+/-9.4 kg, lean mass 69.0+/-8.0 kg) were assessed during the first week of pre-season training for anthropometry, flexibility, lower limb strength and power, speed and agility. Over the subsequent 45 week competitive season all hamstring injuries were diagnosed and recorded. Multiple logistic regression analysis was performed to link individual physical and performance capabilities with propensity to sustain a hamstring injury. A model containing age, lean mass, non-counter movement jump (NCM) performance and active hip flexion range of movement (ROM) was significantly (p<0.05) associated with increased propensity for hamstring injury. Odds for sustaining an injury increased x 1.78 for each 1 year increase in age, x 1.47 for each 1cm increase in NCM and x 1.29 for each 1 degrees decrease in active range of hip flexion. Older, more powerful and less flexible soccer players are at greater risk of sustaining a hamstring injury. Support staff should identify such individuals and make appropriate interventions to minimise risk without compromising performance capabilities.

The effects of contrast bathing and compression therapy on muscular performance.

UNLABELLED Contrast bathing (CB) and compression garments (CG) are widely used to promote recovery. PURPOSE To evaluate CB and CG as regeneration strategies after exercise-induced muscle damage (EIMD). METHODS Baseline values of muscle soreness, serum creatine kinase (CK) and myoglobin (Mb), joint range of motion, limb girth, 10- or 30-m sprint, countermovement jump (CMJ), and five repetition maximum squat were completed by 26 young men who then undertook a resistance exercise challenge (REC) to induce EIMD: 6 x 10 parallel squats at 100% body weight with 5-s one repetition maximum eccentric squat superimposed onto each set. After the REC, subjects were separated into three intervention groups: CB, CG, and control (CONT). Forty-eight hours after REC, the subjects exercise performance was reassessed. CK and Mb were also measured +1, +24, and +48 h post-REC. RESULTS CK was elevated at +24 h ( upward arrow140%; upward arrow161%; upward arrow270%), and Mb was elevated at +1 h ( upward arrow523%; upward arrow458%; upward arrow682%) in CB, CG, and CONT. Within-group large effect sizes for loge[CK] were found for CB at +24 h (0.80) and +48 h (0.84). Area under the [Mb] curve was lower in CB compared with CG and CONT (P < or = 0.05). At +48 h, significant differences from baseline were found in all groups for CMJ (CG, downward arrow5.1%; CB, downward arrow4.4%; CONT, downward arrow8.5%) and soreness ( upward arrow213%; upward arrow284%; upward arrow284%). Soreness transiently fell at +1 h compared with post-REC in the CB group. At +48 h, midthigh girth increased in CB ( upward arrow1.4%) and CONT ( upward arrow1.6%), whereas 30-m sprint time increased in CG ( upward arrow2%). CONCLUSION No hierarchy of recovery effects was found. Neither contrast bathing nor compression acted to promote acute recovery from EIMD any more effectively than passive conditions, although contrast bathing may transiently attenuate postexercise soreness.

Motion analysis of match-play in elite U12 to U16 age-group soccer players

Abstract The aim of this study was to quantify the motion demands of match-play in elite U12 to U16 age-group soccer players. Altogether, 112 players from two professional soccer clubs at five age-group levels (U12–U16) were monitored during competitive matches (n = 14) using a 5 Hz non-differential global positioning system (NdGPS). Velocity thresholds were normalized for each age-group using the mean squad times for a flying 10 m sprint test as a reference point. Match performance was reported as total distance, high-intensity distance, very high-intensity distance, and sprint distance. Data were reported both in absolute (m) and relative (m · min−1) terms due to a rolling substitute policy. The U15 (1.35 ± 0.09 s) and U16 (1.31 ± 0.06 s) players were significantly quicker than the U12 (1.58 ± 0.10 s), U13 (1.52 ± 0.07 s), and U14 (1.51 ± 0.08 s) players in the flying 10 m sprint test (P < 0.001). The U16 age-group covered significantly more absolute total distance (U16 > U12, U13, U14), high-intensity distance (U16 > U12, U13, U14, U15), very high-intensity distance (U16 > U12, U13), and sprint distance (U16 > U12, U13) than their younger counterparts (P < 0.05). When the data are considered relative to match exposure, few differences are apparent. Training prescription for youth soccer players should consider the specific demands of competitive match-play in each age-group.

The Interchangeability of Global Positioning System and Semiautomated Video-Based Performance Data During Elite Soccer Match Play

Harley, JA, Lovell, RJ, Barnes, CA, Portas, MD, and Weston, M. The interchangeability of GPS and semiautomated video-based performance data during elite soccer match play. J Strength Cond Res 25(8): 2334-2336, 2011—In elite-level soccer, player motion characteristics are commonly generated from match play and training situations using semiautomated video analysis systems and global positioning system (GPS) technology, respectively. Before such data are used collectively to quantify global player load, it is necessary to understand both the level of agreement and direction of bias between the systems so that specific interventions can be made based on the reported results. The aim of this report was to compare data derived from both systems for physical match performances. Six elite-level soccer players were analyzed during a competitive match using semiautomated video analysis (ProZone® [PZ]) and GPS (MinimaxX) simultaneously. Total distances (TDs), high speed running (HSR), very high speed running (VHSR), sprinting distance (SPR), and high-intensity running distance (HIR; >4.0 m·s-1) were reported in 15-minute match periods. The GPS reported higher values than PZ did for TD (GPS: 1,755.4 ± 245.4 m; PZ: 1,631.3 ± 239.5 m; p < 0.05); PZ reported higher values for SPR and HIR than GPS did (SPR: PZ, 34.1 ± 24.0 m; GPS: 20.3 ± 15.8 m; HIR: PZ, 368.1 ± 129.8 m; GPS: 317.0 ± 92.5 m; p < 0.05). Caution should be exercised when using match-load (PZ) and training-load (GPS) data interchangeably.

Factors affecting the likelihood to engage in adequate physical activity to promote health

The aim of this study was to assess the likelihood of individuals to participate in enough physical activity to promote fitness and, more conservatively, to accrue only health benefits. Sedentary ( n = 883; 20.5%) and active ( n = 1144; 26.5%) groups were identified from the 1990 Allied Dunbar National Fitness Survey of English adults ( n = 4316). The data were analysed using logistic regression. Participants were described using 20 variables identified from previous research, six of which made a significant contribution to the model ( P ≪ 0.05). The odds of being sedentary increased with age, self-perception of lifestyle problems, and lower scores on education, self-perception of motivation to exercise, perception of own participation in physical activity and recognition of exercising enough for health benefits. The odds of being active were associated with the opposite characteristics to those observed for sedentary behaviour. The extreme scores varied from individuals who may be 385 times more likely to be sedentary, to those who were 29 times more likely to be active, depending on scores on the selected variables. The results of this study provide a means to determine individual propensity to participate in adequate physical activity, and to identify those who may benefit most from health promotion campaigns.

A comparison of FA Premier League referee and player match work rates

Kinematic research into the golf swing has focused on significant differences based on handicap. Within these studies shot outcome has not been quantified or measured. The aim of this study was to determine whether kinematic and temporal differences exist, based on quality of shot, in skilled players.Physical activity promotion through activeThree-dimensional motions commonly models segments with six degrees of freedom (6 DOF) from which joint angles are determined. Implicitly it is assumed that, based on their position and orientations in the standing calibration, segments do not separate. However, marker movement artefacts and measurement error during tracking may lead to exaggerated motion about some of the degrees of freedom. Inverse kinematics (IK) is an alternative approach where joint constraints are explicitly defined and generalised coordinates required by the kinematic chain to achieve a desired pose are determined. The aim of this study was to compare lower limb joint kinematics during the golf swing using 6 DOF and IK models.

Motion characteristics of elite 12- to 16-year old soccer match-play

Kinematic research into the golf swing has focused on significant differences based on handicap. Within these studies shot outcome has not been quantified or measured. The aim of this study was to determine whether kinematic and temporal differences exist, based on quality of shot, in skilled players.Physical activity promotion through activeThree-dimensional motions commonly models segments with six degrees of freedom (6 DOF) from which joint angles are determined. Implicitly it is assumed that, based on their position and orientations in the standing calibration, segments do not separate. However, marker movement artefacts and measurement error during tracking may lead to exaggerated motion about some of the degrees of freedom. Inverse kinematics (IK) is an alternative approach where joint constraints are explicitly defined and generalised coordinates required by the kinematic chain to achieve a desired pose are determined. The aim of this study was to compare lower limb joint kinematics during the golf swing using 6 DOF and IK models.

The effect of prior training load on soccer referees’ physical match performances

Kinematic research into the golf swing has focused on significant differences based on handicap. Within these studies shot outcome has not been quantified or measured. The aim of this study was to determine whether kinematic and temporal differences exist, based on quality of shot, in skilled players.Physical activity promotion through activeThree-dimensional motions commonly models segments with six degrees of freedom (6 DOF) from which joint angles are determined. Implicitly it is assumed that, based on their position and orientations in the standing calibration, segments do not separate. However, marker movement artefacts and measurement error during tracking may lead to exaggerated motion about some of the degrees of freedom. Inverse kinematics (IK) is an alternative approach where joint constraints are explicitly defined and generalised coordinates required by the kinematic chain to achieve a desired pose are determined. The aim of this study was to compare lower limb joint kinematics during the golf swing using 6 DOF and IK models.

Motion characteristics and heart rate responses during soccer training games

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.