Sean Sankey

With developments in tactical complexity in association football (soccer) general intelligence and decision-making are becoming increasingly important attributes for players at all levels. However, an absence of evidence regarding general intelligence and decision-making across different positions within English Academy soccer indicates that it is unknown how specific intelligence in soccer needs to be for successful performance. This study aimed to 1) examine differences in general intelligence scores between different playing positions, 2) investigate differences in coach assessed decision-making ability between different playing positions and 3) assess differences between general intelligence test score ranks and decision-making ranks awarded by coaches to each player per position. One hundred and one participants, aged 16–18 years were recruited from eight clubs in the English Football League. Participants completed an established psychometric test of general intelligence and the lead development phase coach at each club ranked players' decision-making ability. There were 99 outfield players who participated: 37 defenders, 34 midfielders and 28 attackers. No difference was found in general intelligence scores between playing positions. However, a significant difference was found in decision-making ranks, with coaches determining attacker's decision-making to be lower than midfielders and defenders. Likewise , no difference was found between general intelligence and decision-making ranks for either defenders or midfielders, but a difference was observed between attackers' general intelligence and decision-making ranks. In conclusion, attacker's game intelligence appears to be underestimated by coaches. Consequently, utilisation of a psychometric test of general intelligence could enhance identification of talented players in Academy soccer.

Most athletes that return to sport (RTS) after Anterior Cruciate Ligament (ACL) injury undergo reconstruction (ACLR) to restore their knee stability. The major concern for RTS is for the patient to be able to perform chal-lenging dynamic tasks whilst adequately stabilizing the knee joint and maintaining their postural balance. Nevertheless, the interaction between knee protective mechanisms (such as knee unloading and knee stabilisa-tion) and postural balance strategies has not yet been comprehensively analyzed. Thus, the aim of this study was to investigate landing balance strategies in ACLR athletes at time of RTS. Twenty-one athletes with a unilateral ACLR were tested at the time of RTS while performing a single leg hop for distance on both limbs. Three balance mechanisms that influence the GRF during the landing phase (foot placement, center of pressure (CoP) excursion, counter-rotation of segments) were investigated and compared between the ACL injured and uninjured limb. Interactions between knee protective mechanisms and postural balance strategies were tested using a statistical parametric mapping regression analysis. Results show that CoP excursions in the injured limb increased, as well as ankle joint moment contribution to anterior-posterior (A-P) GRF. Besides, patients presenting reduced knee joint contribution to A-P GRF had to compensate with higher hip joint contribution in order to maintain postural balance. In conclusion, ACLR athletes who at RTS still protect their reconstructed knee are forced to employ compensatory postural balance strategies. Therefore, there is a persistent trade-off between knee protection and postural balance at the moment of RTS.

The purpose of this study was to identify the anticipatory effects on factors that influence the ability to generate medial ground reaction forces in changes of direction, and the implications for injury risk markers. Twenty recreational soccer players completed 12 anticipated and 12 unanticipated side cutting tasks, whilst 3D motion capture and force plate data were collected. Five distinct movement strategies were found to represent factors that influence the medial ground reaction force vector, and comparisons were made between the two conditions using multiple t-tests in SPM1D. Whole-body dynamic stability is compromised by limited anticipation time, with a greater demand on a corrective hip strategy following a narrower foot placement and reduced sagittal plane loading efficiency. This may have implications for change of direction performance and injury risk.

Control of the centre of mass (CoM) whilst minimising the use of unnecessary movements is imperative for successful performance of dynamic sports tasks, and may indicate the condition of whole-body dynamic stability. The aims of this study were to express movement strategies that represent whole-body dynamic stability, and to explore their association with potentially injurious joint mechanics and side cutting performance. Twenty recreational soccer players completed 45° unanticipated side cutting. Five distinct whole-body dynamic stability movement strategies were identified, based on factors that influence the medial ground reaction force (GRF) vector during ground contact in the side cutting manoeuvre. Using Statistical Parametric Mapping, the movement strategies were linearly regressed against selected performance outcomes and peak knee abduction moment (peak KAM). Significant relationships were found between each movement strategy and at least one selected performance outcome or peak KAM. Our results suggest excessive medial GRFs were generated through sagittal plane movement strategies, and despite being beneficial for performance aspects, poor sagittal plane efficiency may destabilise control of the CoM. Frontal plane hip acceleration is the key non-sagittal plane movement strategy used in a corrective capacity to moderate excessive medial forces. However, whilst this movement strategy offered a way to retrieve control of the CoM, mitigating reduced whole-body dynamic stability, it also coincided with increased peak KAM. Overall, whole-body dynamic stability movement strategies helped explain the delicate interplay between the mechanics of changing direction and undesirable joint moments, providing insights that might support development of future intervention strategies.

Introduction: Side-cutting tasks are commonly used in dynamic assessment of ACL injury risk, but only limited information is available concerning the reliability of knee loading parameters. The aim of this study was to investigate the reliability of side-cutting data with additional focus on modelling approaches and task execution variables.
Methods: Each subject (n=8) attended six testing sessions conducted by two observers. Kinematic and kinetic data of 45° side-cutting tasks was collected. Inter-trial, inter-session, inter-observer variability and observer/trial ratios were calculated at every time-point of normalised stance, for data derived from two modelling approaches. Variation in task execution variables was regressed against that of temporal profiles of relevant knee data using one-dimensional statistical parametric mapping.
Results: Variability in knee kinematics was consistently low across the time-series waveform (≤5 °), but knee kinetic variability was high (31.8, 24.1 and 16.9 Nm for sagittal, frontal and transverse planes, respectively) in the weight acceptance phase of the side-cutting task. Calculations conveyed consistently moderate-to-good measurement reliability. Inverse kinematic modelling reduced the variability in sagittal (~6 Nm) and frontal planes (~10 Nm) compared to direct kinematic modelling. Variation in task execution variables did not explain any knee data variability.
Conclusion: Side-cutting data appears to be reliably measured, however high knee moment variability exhibited in all planes, particularly in the early stance phase, suggests cautious interpretation towards ACL injury mechanics. Such variability may be inherent to the dynamic nature of the side-cutting task or experimental issues not yet known.

This study aimed to investigate whether treadmill versus overground soccer match simulations have similar effects on knee joint mechanics during side cutting. Nineteen male recreational soccer players completed a 45 min treadmill and overground match simulation. Heart rate (HR) and rating of perceived exertion (RPE) were recorded every 5 min. Prior to exercise (time 0 min), at ‘half-time’ (time 45 min) and 15 min post exercise (time 60 min) participants performed five trials of 45° side cutting manoeuvres. Knee abduction moments and knee extension angles were analysed using two-way repeated measures ANOVA (α = 0.05). Physiological responses were significantly greater during the overground (HR 160 ± 7 beats ∙ min-1; RPE 15 ± 2) than treadmill simulation (HR 142 ± 5 beats ∙ min-1; RPE 12 ± 2). Knee extension angles significantly increased over time and were more extended at time 60 min compared with time 0 min and time 45 min. No significant differences in knee abduction moments were observed. Although knee abduction moments were not altered over time during both simulations, passive rest during half-time induced changes in knee angles that may have implications for ACL injury risk.

Strength assessment is often part of the objective periodical observation of teams, squads, or large groups of athletes. Equipment that provides assessment that is mobile and is easy to use will reduce the impact on the athletes’ training and competitive calendar. However, any equipment used must be reliable to allow accurate monitoring of performance. The aim of this study was to examine the reliability of the Concept2 Dyno dynamometer. Forty-six competitive athletes (males: n = 36, age 23.3 6 6.8 years, height 1.80 6 0.09 m, body mass 82.3 6 15.6 kg; females, n = 10, age 20.7 6 1.4 years, height 1.65 6 0.09 m, body mass 62.7 6 11.8 kg), with a strength training background of more than 2 years, performed a familiarization session and 3 experimental sessions with 1 week intervening each. Each experi- mental session consisted of 3 maximal efforts of seated chest press (CPress), seated row (SRow), and seated leg press (LPress) exercises. Reliability was assessed examining systematic bias, intraclass correlation coefficient, coefficient of variation (CV), and 95% limits of agreement (95% LoA) between sessions. No systematic bias was found for any of the exercises. Intraclass correlation coefficients were high (0.89–0.98) with relatively low CV (6.2–4.3%). Finally, 95% LoA indicated that subsequent testing could underestimate by a factor of 0.87 or overestimate by a factor of 1.17, on average. These results indicate that Concept2 Dyno dynamometer is reliable and can be used in the field to efficiently monitor strength performance. Coaches and researchers should use “analytical goals” to help decide as to the use of Concept2 Dyno for their purposes.

Purpose: As drop vertical jumps (DVJ) are widely used as a screening task, the assessment of the reliability of lower-limb biomechanical parameters during DVJ is important. The aim of this study was to assess the reliability of the kinematic and kinetic peak values as well as of the waveforms for lower-limb parameters obtained with the Liverpool John Moores University biomechanical model (LJMU model) during performance of DVJ. Methods: The reliability was analyzed by calculating the intertrial (o¸trial), intersession (o¸sess), and intertherapist (o¸ther) errors of hip and knee joint parameters in a repeated-measures design including two therapists and a total of six sessions. Results: The results showed o¸trial that ranged from 1.1- to 3.5- for all peak kinematic parameters and from 3.6 to 12.9 NIm for all peak kinetic parameters. The o¸sess of the peak values ranged from 1.9- to 5.7- for all angles and from 5.4 to 19.8 NIm for the hip and knee joint moments in all planes. The o¸ther of the peak values ranged from 2.7- to 6.4- for all angles and from 5.8 to 22.4 NIm for all moments. Most of the kinematic and kinetic peak parameters had o¸ther-trial e 2.0- and 4.3 NIm, respectively, suggesting a small extrinsic variability. Furthermore, the entire waveforms also showed a rather high o¸trial relative to other types of variability. Conclusions: The present findings indicated that DVJ kinetics and kinematics show small extrinsic variability. The reported errors are useful for clinical interpretation processes of DVJ performance as screening task for injury risk and rehabilitation outcome taking into consideration the different types of measurement error over time.