Chris Button

Skill acquisition in sport: some applications of an evolving practice ecology

This paper builds on recent theoretical concerns regarding traditional conceptualizations of the skill acquisition process. The implications for the process of practice in sport contexts are explored with reference to the information-processing approach to motor behaviour and the newer ecological paradigm. Issues are raised with current principles of practice based on traditional theoretical ideas. A practice strategy that gives greater weight to the guided exploration of the practice workspace jointly defined by the properties of the individuals subsystems, the specific task and the environment is advocated. Such a constraints-led perspective supersedes previous distinctions between rudimentary and voluntary skills. Sports scientists, coaches, teachers and movement rehabilitation therapists are invited to review current practices in the light of recent theoretical advances from the ecological perspective.

Influence Of Familiarization On The Reliability Of Vertical Jump And Acceleration Sprinting Performance In Physically Active Men

The purpose of the present study was to determine the number of familiarization sessions required to obtain an accurate measure of reliability associated with loaded vertical jump and 20-m sprint running performance. Ten physically active men attended 5 separate testing sessions over a 3-week period where they performed unloaded and loaded (10-kg extra load) countermovement (CMJ) and static (SJ) jumps, followed by straight-line 20-m sprints. Jump height was recorded for the vertical jumps using a jump mat, while the time for 10 m and 20 m was recorded during the sprints using photocells. The highest (jump conditions) and fastest (sprint) of 3 trials performed during each of the 5 testing sessions was used in the subsequent analysis. Familiarization was assessed using the scores obtained during the 5 separate testing sessions. Reliability was assessed by calculating intra-class correlation coefficients (ICCs) and coefficient of variation (CV). No significant differences were obtained between the testing sessions for any of the measures. ICCs ranged from 0.89 to 0.95, while CVs ranged from 1.9 to 2.6%. These results indicate that high levels of reliability can be achieved without the need for familiarization sessions when using loaded and unloaded CMJ and SJ and 20-m sprint performance with physically active men.

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.

Examining Movement Variability in the Basketball Free-Throw Action at Different Skill Levels

Abstract The analysis of variability both within and between performers can reveal important information about how athletes satisfy situational constraints. Transitory changes in the basketball free-throw shot were examined across different stages in skill development. Six female basketball players were selected, representing a range of playing expertise (pretest: 0–90% baskets scored). Each participant was video recorded performing 30 shots. Contrary to predictions, there was not a clear pattern of a reduction in trajectory variability with increasing skill level. However, improvements in skill level were associated with an increasing amount of intertrial movement consistency from the elbow and wrist joints. It is suggested that the angular motions of the elbow and wrist joints were compensated for each other toward the end of each throw to adapt to subtle changes in release parameters of the ball.

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.

The Role of Ecological Dynamics in Analysing Performance in Team Sports

Performance analysis is a subdiscipline of sports sciences and one-approach, notational analysis, has been used to objectively audit and describe behaviours of performers during different subphases of play, providing additional information for practitioners to improve future sports performance. Recent criticisms of these methods have suggested the need for a sound theoretical rationale to explain performance behaviours, not just describe them. The aim of this article was to show how ecological dynamics provides a valid theoretical explanation of performance in team sports by explaining the formation of successful and unsuccessful patterns of play, based on symmetrybreaking processes emerging from functional interactions between players and the performance environment. We offer the view that ecological dynamics is an upgrade to more operational methods of performance analysis that merely document statistics of competitive performance. In support of our arguments, we refer to exemplar data on competitive performance in team sports that have revealed functional interpersonal interactions between attackers and defenders, based on variations in the spatial positioning of performers relative to each other in critical performance areas, such as the scoring zones. Implications of this perspective are also considered for practice task design and sport development programmes.

A Review of Vision-Based Motion Analysis in Sport

Efforts at player motion tracking have traditionally involved a range of data collection techniques from live observation to post-event video analysis where player movement patterns are manually recorded and categorized to determine performance effectiveness. Due to the considerable time required to manually collect and analyse such data, research has tended to focus only on small numbers of players within predefined playing areas. Whilst notational analysis is a convenient, practical and typically inexpensive technique, the validity and reliability of the process can vary depending on a number of factors, including how many observers are used, their experience, and the quality of their viewing perspective. Undoubtedly the application of automated tracking technology to team sports has been hampered because of inadequate video and computational facilities available at sports venues. However, the complex nature of movement inherent to many physical activities also represents a significant hurdle to overcome. Athletes tend to exhibit quick and agile movements, with many unpredictable changes in direction and also frequent collisions with other players. Each of these characteristics of player behaviour violate the assumptions of smooth movement on which computer tracking algorithms are typically based. Systems such as TRAKUS™, SoccerMan™, TRAKPERFORMANCE™, Pfinder™ and Prozone™ all provide extrinsic feedback information to coaches and athletes. However, commercial tracking systems still require a fair amount of operator intervention to process the data after capture and are often limited by the restricted capture environments that can be used and the necessity for individuals to wear tracking devices. Whilst some online tracking systems alleviate the requirements of manual tracking, to our knowledge a completely automated system suitable for sports performance is not yet commercially available. Automatic motion tracking has been used successfully in other domains outside of elite sport performance, notably for surveillance in the military and security industry where automatic recognition of moving objects is achievable because identification of the objects is not necessary. The current challenge is to obtain appropriate video sequences that can robustly identify and label people over time, in a cluttered environment containing multiple interacting people. This problem is often compounded by the quality of video capture, the relative size and occlusion frequency of people, and also changes in illumination. Potential applications of an automated motion detection system are offered, such as: planning tactics and strategies; measuring team organisation; providing meaningful kinematic feedback; and objective measures of intervention effectiveness in teamsports, which could benefit coaches, players, and sports scientists.

Key properties of expert movement systems in sport

This paper identifies key properties of expertise in sport predicated on the performer-environment relationship. Weaknesses of traditional approaches to expert performance, which uniquely focus on the performer and the environment separately, are highlighted by an ecological dynamics perspective. Key properties of expert movement systems include ‘multi- and meta-stability’, ‘adaptive variability’, ‘redundancy’, ‘degeneracy’ and the ‘attunement to affordances’. Empirical research on these expert system properties indicates that skill acquisition does not emerge from the internal representation of declarative and procedural knowledge, or the imitation of expert behaviours to linearly reduce a perceived ‘gap’ separating movements of beginners and a putative expert model. Rather, expert performance corresponds with the ongoing co-adaptation of an individual’s behaviours to dynamically changing, interacting constraints, individually perceived and encountered. The functional role of adaptive movement variability is essential to expert performance in many different sports (involving individuals and teams; ball games and outdoor activities; land and aquatic environments). These key properties signify that, in sport performance, although basic movement patterns need to be acquired by developing athletes, there exists no ideal movement template towards which all learners should aspire, since relatively unique functional movement solutions emerge from the interaction of key constraints.

The influence of familiarization on the reliability of force variables measured during unloaded and loaded vertical jumps.

The purpose of this study was to determine the number of familiarization sessions required to obtain an accurate measure of reliability associated with force variables recorded during unloaded and loaded (30 and 60% of 1 repetition maximum squat [1RM]) static vertical jumps (SJ). Nine physically active men attended 4 separate testing sessions over a 2-week period. Force platform recordings of peak force, peak rate of force development (pRFD), average rate of force development, takeoff velocity, average power, and peak power were obtained for each jump. During each of the 4 testing sessions, 3 jumps were performed under each of the load conditions. The average of the force variables were used in the analysis. Familiarization was assessed using the scores obtained during the 4 separate testing sessions. Reliability was assessed by calculating intraclass correlation coefficients (ICCs) and coefficient of variation (CV) associated with the force variables. No significant differences (p > 0.05) were obtained between the testing sessions for any of the force variables. With the exception of pRFD, the force variables showed reasonably good levels of test-retest reliability (ICC range: 0.75–0.99; CV range: 1.2–7.6%). High levels of reliability can be achieved in a variety of force variables without the need for familiarization sessions when performing SJ under unloaded conditions and with loads of 30 and 60% of 1RM squat with physically active men.

Variation in coordination of a discrete multiarticular action as a function of skill level.

The authors investigated coordination modes that emerged as a function of the interaction between skill level and task constraints in a multiarticular kicking action. Five skilled, 5 intermediate, and 5 novice participants attempted to satisfy specific height and accuracy constraints in kicking a ball over a barrier. Skilled and intermediate groups demonstrated a functional coordination mode involving less joint involvement at the proximal joints and greater joint involvement at distal joints, mimicking a chip-like action in soccer. Conversely, the novice group tended to produce larger ranges of motion throughout the kicking limb in a driving-like kicking action. Key differences were also found for task outcome scores, joint angle-angle relations, and ball-trajectory plots between the skilled and intermediate groups and the novice group. Findings from this study demonstrated that joint involvement during this discrete multiarticular action is a function of skill level and task constraints rather than a consequence of a global freezing-freeing strategy suggested in some previous research. The authors also highlight the merit of using a model of the acquisition of coordination in examining how coordination modes for multiarticular actions differ as a function of skill.