Ian Renshaw

Expert performance in sport and the dynamics of talent development.

Research on expertise, talent identification and development has tended to be mono-disciplinary, typically adopting genocentric or environmentalist positions, with an overriding focus on operational issues. In this paper, the validity of dualist positions on sport expertise is evaluated. It is argued that, to advance understanding of expertise and talent development, a shift towards a multidisciplinary and integrative science focus is necessary, along with the development of a comprehensive multidisciplinary theoretical rationale. Here we elucidate dynamical systems theory as a multidisciplinary theoretical rationale for capturing how multiple interacting constraints can shape the development of expert performers. This approach suggests that talent development programmes should eschew the notion of common optimal performance models, emphasize the individual nature of pathways to expertise, and identify the range of interacting constraints that impinge on performance potential of individual athletes, rather than evaluating current performance on physical tests referenced to group norms.

The Role of Nonlinear Pedagogy in Physical Education

In physical education, the Teaching Games for Understanding (TGfU) pedagogical strategy has attracted significant attention from theoreticians and educators for allowing the development of game education through a tactic-to-skill approach involving the use of modified games. However, some have proposed that as an educational framework, it lacks adequate theoretical grounding from a motor learning perspective to empirically augment its perceived effectiveness. The authors examine the literature base providing the theoretical underpinning for TGfU and explore the potential of a nonlinear pedagogical framework, based on dynamical systems theory, as a suitable explanation for TGfU’s effectiveness in physical education. Nonlinear pedagogy involves manipulating key task constraints on learners to facilitate the emergence of functional movement patterns and decision-making behaviors. The authors explain how interpreting motor learning processes from a nonlinear pedagogical framework can underpin the educational principles of TGfU and provide a theoretical rationale for guiding the implementation of learning progressions in physical education.

A constraints-led perspective to understanding skill acquisition and game play: a basis for integration of motor learning theory and physical education praxis?

Background: In order to design appropriate environments for performance and learning of movement skills, physical educators need a sound theoretical model of the learner and of processes of learning. In physical education, this type of modelling informs the organisation of learning environments and effective and efficient use of practice time. An emerging theoretical framework in motor learning, relevant to physical education, advocates a constraints-led perspective for acquisition of movement skills and game play knowledge. This framework shows how physical educators could use task, performer and environmental constraints to channel acquisition of movement skills and decision-making behaviours in learners. From this viewpoint, learners generate specific movement solutions to satisfy the unique combination of constraints imposed on them, a process which can be harnessed during physical education lessons. Aims: In this paper the aim is to provide an overview of the motor learning approach emanating from the constraints-led perspective, and examine how it can substantiate a platform for a new pedagogical framework in physical education: nonlinear pedagogy. We aim to demonstrate that it is only through theoretically valid and objective empirical work of an applied nature that a conceptually sound nonlinear pedagogy model can continue to evolve and support research in physical education. We present some important implications for designing practices in games lessons, showing how a constraints-led perspective on motor learning could assist physical educators in understanding how to structure learning experiences for learners at different stages, with specific focus on understanding the design of games teaching programmes in physical education, using exemplars from Rugby Union and Cricket. Findings: Research evidence from recent studies examining movement models demonstrates that physical education teachers need a strong understanding of sport performance so that task constraints can be manipulated so that information–movement couplings are maintained in a learning environment that is representative of real performance situations. Physical educators should also understand that movement variability may not necessarily be detrimental to learning and could be an important phenomenon prior to the acquisition of a stable and functional movement pattern. We highlight how the nonlinear pedagogical approach is student-centred and empowers individuals to become active learners via a more hands-off approach to learning. Conclusions: A constraints-based perspective has the potential to provide physical educators with a framework for understanding how performer, task and environmental constraints shape each individuals physical education. Understanding the underlying neurobiological processes present in a constraints-led perspective to skill acquisition and game play can raise awareness of physical educators that teaching is a dynamic ‘art’ interwoven with the ‘science’ of motor learning theories.

Movement Models from Sports Provide Representative Task Constraints for Studying Adaptive Behavior in Human Movement Systems

Researchers studying adaptive behavior in human movement systems have traditionally employed simplified, laboratory-based movement models in an effort to conserve experimental rigor. Brunswikian psychology raises questions over the representativeness of many of these popular experimental models for studying how movements are coordinated with events, objects, and surfaces of dynamic environments. In this article we argue that sports provide rich ecological constraints for representative task design in modeling the complex interactions of human performers with their environments. Adopting a functionalist perspective enriched by ideas from ecological psychology and nonlinear dynamics, we consider data from exemplar movement models in basketball and boxing to support this contention. We show that this preference for movement models from sports, although not completely novel, has accelerated over recent years, mainly due to the theoretical re-emphasis on studying the interaction of individual and task constraints. The implications of using such applied models of move ment behavior in studying the design of natural and artificial systems are also discussed.

Interactive processes link the multiple symptoms of fatigue in sport competition

Muscle physiologists often describe fatigue simply as a decline of muscle force and infer this causes an athlete to slow down. In contrast, exercise scientists describe fatigue during sport competition more holistically as an exercise-induced impairment of performance. The aim of this review is to reconcile the different views by evaluating the many performance symptoms/measures and mechanisms of fatigue. We describe how fatigue is assessed with muscle, exercise or competition performance measures. Muscle performance (single muscle test measures) declines due to peripheral fatigue (reduced muscle cell force) and/or central fatigue (reduced motor drive from the CNS). Peak muscle force seldom falls by <30% during sport but is often exacerbated during electrical stimulation and laboratory exercise tasks. Exercise performance (whole-body exercise test measures) reveals impaired physical/technical abilities and subjective fatigue sensations. Exercise intensity is initially sustained by recruitment of new motor units and help from synergistic muscles before it declines. Technique/motor skill execution deviates as exercise proceeds to maintain outcomes before they deteriorate, e.g. reduced accuracy or velocity. The sensation of fatigue incorporates an elevated rating of perceived exertion (RPE) during submaximal tasks, due to a combination of peripheral and higher CNS inputs. Competition performance (sport symptoms) is affected more by decision-making and psychological aspects, since there are opponents and a greater importance on the result. Laboratory based decision making is generally faster or unimpaired. Motivation, self-efficacy and anxiety can change during exercise to modify RPE and, hence, alter physical performance. Symptoms of fatigue during racing, team-game or racquet sports are largely anecdotal, but sometimes assessed with time-motion analysis. Fatigue during brief all-out racing is described biomechanically as a decline of peak velocity, along with altered kinematic components. Longer sport events involve pacing strategies, central and peripheral fatigue contributions and elevated RPE. During match play, the work rate can decline late in a match (or tournament) and/or transiently after intense exercise bursts. Repeated sprint ability, agility and leg strength become slightly impaired. Technique outcomes, such as velocity and accuracy for throwing, passing, hitting and kicking, can deteriorate. Physical and subjective changes are both less severe in real rather than simulated sport activities. Little objective evidence exists to support exercise-induced mental lapses during sport.A model depicting mind-body interactions during sport competition shows that the RPE centre-motor cortex-working muscle sequence drives overall performance levels and, hence, fatigue symptoms. The sporting outputs from this sequence can be modulated by interactions with muscle afferent and circulatory feedback, psychological and decision-making inputs. Importantly, compensatory processes exist at many levels to protect against performance decrements. Small changes of putative fatigue factors can also be protective.We show that individual fatigue factors including diminished carbohydrate availability, elevated serotonin, hypoxia, acidosis, hyperkalaemia, hyperthermia, dehydration and reactive oxygen species, each contribute to several fatigue symptoms. Thus, multiple symptoms of fatigue can occur simultaneously and the underlying mechanisms overlap and interact. Based on this understanding, we reinforce the proposal that fatigue is best described globally as an exercise-induced decline of performance as this is inclusive of all viewpoints.

Cricket bowling deliveries and the discrimination ability of professional and amateur batters

Bowlers in cricket try to disguise their bowling action by movement pattern similarity. The batter’s task is, therefore, to solve rapidly perceptual discrimination problems. Previous research has suggested that batters can discriminate perceptual cues that provide depth or target information. However, at present, there is a lack of applied research evidence on further perceptual cue utilization, including bowling delivery identification. This ability is required when batting against wrist-spin bowlers who may use five different types of delivery. In the present study, we assessed this perceptual discrimination ability among three distinct standards of batters. In addition, the relative potency of body action and ball flight information was assessed by visual occlusion techniques. We found that more expert batters in general showed greater perceptual discrimination skills when faced with different ball types. However, this discrimination ability was linked specifically to delivery type and to previous experience. We also found that additional ball flight information provided no more advantage to this discrimination ability. This finding reinforces the importance of advanced cue information and the need to expose cricket batters to different bowling actions. Further study of the development of movement pattern recognition is recommended.

Changing ecological constraints of practice alters coordination of dynamic interceptive actions

Abstract The ecological constraints of practice have a significant effect on the acquisition of functional information–movement couplings and learners need to converge on information-specifying perceptual variables. Consequently, the prolonged and widespread use of ball projection machines for the practice of interceptive actions may lack theoretical foundation because they afford information-specifying variables that are not present in competition. The timing and coordination of the forward defensive stroke in cricket batting were examined in experienced batters under two typical practice task constraints: batting against a representative “real” bowler and a representative bowling machine (mean delivery velocity 26.76 m·s−1 under both conditions). Significant adaptation of coordination and timing was observed under the different practice task constraints. For example, initiation of the backswing was later against a bowler and downswing was faster with a different ratio of backswing–downswing when batting against the bowling machine (47%–53%) compared with the bowler (54%–46%). Peak bat height differed under the two constraints (bowling machine: mean 1.56 m, s=19.89; bowler: 1.72 m, s=10.36 m). Mean length of front foot stride was shorter against the bowling machine (0.55 m, s=0.07 m) than the bowler (0.59 m, s=0.06 m). The correlation between initiation of backswing and front foot movement was much higher against the bowler (r = 0.88) than the bowling machine (r=0.65).

Information–movement coupling in developing cricketers under changing ecological practice constraints

Changing informational constraints of practice, such as when using ball projection machines, has been shown to significantly affect movement coordination of skilled cricketers. To date, there has been no similar research on movement responses of developing batters, an important issue since ball projection machines are used heavily in cricket development programmes. Timing and coordination of young cricketers (n=12, age=15.6+/-0.7years) were analyzed during the forward defensive and forward drive strokes when facing a bowling machine and bowler (both with a delivery velocity of 28.14+/-0.56ms(-1)). Significant group performance differences were observed between the practice task constraints, with earlier initiation of the backswing, front foot movement, downswing, and front foot placement when facing the bowler compared to the bowling machine. Peak height of the backswing was higher when facing the bowler, along with a significantly larger step length. Altering the informational constraints of practice caused major changes to the information-movement couplings of developing cricketers. Data from this study were interpreted to emanate from differences in available specifying variables under the distinct practice task constraints. Considered with previous findings, results confirmed the need to ensure representative batting task constraints in practice, cautioning against an over-reliance on ball projection machines in cricket development programmes.

“Essential noise” – enhancing variability of informational constraints benefits movement control: a comment on Waddington and Adams (2003)

This commentary proposes a dynamical systems perspective to re-interpret data from a group of international soccer players demonstrating that wearing textured insoles in soccer boots enhanced tactile information from the sole of the foot and increased movement discrimination capacity in ankle inversion sensitivity tests to levels similar to those in barefoot conditions. Theoretical arguments on the functional role of variability induced in the sensorimotor system by textured insoles, acting as a form of “essential noise” to enhance the accuracy of foot positioning are presented. It seems that, far from interfering with motor performance, variability can actually enhance perception of information to support motor performance. The addition of intermittent, intermediate levels of noise in a perceptual motor context may benefit performers by helping them to pick up information signals from background structure. Movement system variability is conceived as noise induced resonance benefiting the pick up of information to regulate behaviour. Variability can be functional in practical programmes to offset negative effects of losses in sensory sensitivity through ageing, disease, illness, or injury

Nested task constraints shape continuous perception–action coupling control during human locomotor pointing

Behavioural studies of human locomotor pointing have been dominated by specific task constraints of generating maximal approach velocity towards spatial targets. To examine locomotor pointing under different nested task constraints, at sub-maximal approach velocities and with concomitant differences in speed-accuracy trade offs, run-ups of professional cricket bowlers (n = 6) were analysed. Inter- and intra-trial analyses of step length adjustments revealed how differences between current and required locomotor pointing behaviour constrained visual adaptations of gait. Results supported a continuous perception-action coupling control mechanism, although no relationship was observed between step number in sequence and total amount of adjustment made, implying that visual adaptations did not continue to the end of a run-up once initiated. Rather, bowlers made step adjustments throughout the run-up, with strong associations for amount of adjustment made and amount needed. Significant variations were observed in inter-individual strategies for making most adjustments at different points of the run-up. A key premise of prospective control models of locomotor pointing was found to be robust, since regulation of cricketers gait was continuous and based on perception of current and required behaviour. Findings extend understanding of the nature and range of nested task constraints under which perception-action coupling controls locomotor pointing performance.