An ecological dynamics approach to promote physical literacy and well-being of primary school children: a cluster randomised controlled trial study protocol.

BACKGROUND: Little is known about the impact of an ecological dynamics (ED) intervention (EDI) on primary school children's physical literacy and well-being in the Hong Kong context. The aim of this project is to introduce a physical literacy and well-being framework through an EDI that allows primary school children to develop good physical activity (PA) and daily behavioural habits. METHODS AND ANALYSIS: A four-arm (cluster) randomised controlled trial will be conducted to examine the effect of EDI on physical literacy and well-being in primary schools located in each of the 18 administrative districts of Hong Kong. Four classes in senior primary students (grade 4) at each school will be randomly assigned to the four different conditions. These participating schools will be equipped with sit-stand desks, PA recess facility and equipment, and sleep pillows. The research team will adopt both objective measures (aerobic fitness, fundamental movement skills, daily behaviour-physical activity and cognitive function) and self-reported measures (perceived physical literacy, quality of life, sleep quality) covering the elements and domains of physical literacy and well-being to examine the effects of EDIs at four time points, including baseline assessment, 3 months after intervention, postintervention and 3-month follow-up assessment. One-way analyses of variance (ANOVAs) will be used to test for differences in the baseline characteristics of participants between groups. Repeated measure ANOVAs and MANCOVA, with time (baseline, after intervention and follow-up) as within-subjects factor, and intervention group as between-subjects factors, will be used to evaluate the effects of different interventions on the students' physical literacy and well-being. A Bonferonni correction to the p value will be calculated to adjust for multiple tests. ETHICS AND DISSEMINATION: Ethical approval was sought from the Joint CUHK-NTEC Clinical Research Ethics Committee in Hong Kong (CREC Ref.No.:2024.027). The finding of this study will be disseminated via peer-reviewed journals, international conference presentations and academic lectures. For secondary analysis of the data, please contact the corresponding author for permission. TRIAL REGISTRATION NUMBER: ISRCTN84025914.

Different pedagogical approaches to motor imagery both demonstrate individualized movement patterns to achieve improved performance outcomes when learning a complex motor skill.

Cognitive training techniques such as motor imagery (MI)-cognitive simulation of movement, has been found to successfully facilitate skill acquisition. The MI literature emphasizes the need to accurately imitate key elements of motor execution to facilitate improved performance outcomes. However, there is a scarcity of MI research investigating how contemporary approaches to motor learning, such as nonlinear pedagogy (NLP), can be integrated into MI practice. Grounded in an ecological dynamics approach to human movement, NLP proposes that skilled action is an emergent process that results from continuous interactions between perceptual information of the environment and movement. This emergent process can be facilitated by the manipulation of key task constraints that aim to encourage learners to explore movement solutions that satisfy individual constraints (e.g., height and weight) and achieve successful performance outcomes. The aim of the present study was to explore the application of a NLP approach to MI approach for skill acquisition. Fourteen weightlifting beginners (two female and 12 male) participated in a 4-week intervention involving either NLP (i.e. analogy-based instructions and manipulation of task constraints) or a linear pedagogy (LP; prescriptive instructions of optimal technique, repetition of same movement form) to learn a complex weightlifting derivative. Performance accuracy, movement criterion (barbell trajectory type), kinematic data, and quantity of exploration/exploitation were measured pre-mid-post intervention. No significant differences (p = .438) were observed in the amount of exploration between LP (EER = 0.41) and NLP (EER = 0.26) conditions. Equivalent changes in rearward displacement (R×D) were observed with no significant differences between conditions for technique assessments 1, 2, or 3 (p = .13 - .67). Both NLP and LP conditions were found to primarily demonstrate 'sub-optimal' type 3 barbell trajectories (NLP = 72%; LP = 54%). These results suggest that MI instructions prescribing a specific movement form (i.e., LP condition) are ineffective in restricting available movements to a prescribed technique but rather the inherent task constraints appear to 'force' learners to explore alternative movement solutions to achieve successful performance outcomes. Although MI instructions prescribing specific techniques have previously supported improved skill development, the current findings indicate that learners may self-organise their movements regardless of MI instructions to satisfy individual and task constraints while achieving improved performance. Therefore, it may be beneficial to consider scripts that are more outcome focused and incorporate task constraints to facilitate learners' inherent exploration of individual task solutions.

Advice from "pracademics" of how to apply ecological dynamics theory to practice design.

There has been an increase interest in knowing and enacting pedagogical approaches such as the Constraints-led Approach (CLA) and Nonlinear Pedagogy (NLP) which are underpinned by Ecological Dynamics in recent years among practitioners. While there seems to be a perceived uptake of such pedagogical approaches that encourages exploratory learning and the development of individualised movement solutions, there are still concerns on how these pedagogical approaches are enacted on the ground. In this paper, we the authors, as "pracademics", attempted to address some of the common concerns that we are aware of from our regular interactions with academics and practitioners. In brief, we highlighted some of the common challenges related to sense making concepts from Ecological Dynamics and building connections to practice. We stressed the need to invest time to think differently to create representative learning environment, rethink how assessment is to be done, finding a balance between theoretical jargon and practical application as well as intentionally situating coach development and support. We may not have all the answers, but we hope this paper could provide a useful starting point on how to apply Ecological Dynamics Theory to practice design.

The effect of nonlinear pedagogy on the acquisition of game skills in a territorial game.

Introduction: Nonlinear Pedagogy (NP), underpinned by Ecological Dynamics, provides a suitable pedagogical approach for practitioners (e.g., Physical Educators, coaches) to encourage exploratory learning that is learner-centered even in Traditional Sporting Games (TSG) that could be represented by invasion or territorial-like games. NP involves the manipulation of constraints which form boundaries for interacting components to self-organize, facilitating the emergence of goal-directed behaviours. Key pedagogical principles relating to representativeness, manipulation of constraints, awareness of focus of attention instructions, task simplification and the functional role of noise can encourage exploratory learning that helps develop 21st century competencies. This is in contrast to a Linear Pedagogy (LP) approach that is more teacher-centered and focuses on repetition in practices to promote movement form consistency in enhancing the acquisition of movement skills. Little is known about the effectivity of NP in the learning and transfer of invasion games. The aims of this study were to: (a) determine the impact of NP on the teaching and learning of an invasion game in the Physical Education (PE) context; (b) examine the transferability of game skills to other games in the same game category (i.e., floorball as a territorial game in this study). Methods: 224 (between 12 to 13 years old) students underwent a 10-week intervention program to learn to play an invasion game (football) with either a NP or LP approach (i.e., repetitive and prescriptive drills). Results: Performance outcome data were measured during Pre, Post, Retention, Transfer test 1 (larger playing area) and Transfer test 2 (floorball). Significant improvements in several performance outcome and game play measures in football was observed for the NP condition. Fewer improvements in the same measures were found for the LP condition. Discussion: Evidence for transfer of learning for NP was not as strong as anticipated although there was still some potential for encouraging transfer of learning. The key findings from this study further challenge the "one-size fits all" philosophy in the teaching of PE. Both LP and NP approaches would have a role to play in supporting teaching and learning which could be context dependent.

Is Prescription of Specific Movement Form Necessary for Optimal Skill Development? A Nonlinear Pedagogy Approach.

Purpose: Nonlinear Pedagogy (NLP) proposes that skill development is a nonlinear process, advocating the integration of variability into practice to facilitate individualized movement patterns. However, the influence of a NLP for skills that emphasize a specific movement form is relatively unknown. This study aimed to investigate the impact of a NLP approach when learning a movement form based skill. Method: Sixteen beginners in the power clean (PC), were randomly assigned into a linear pedagogy (LP) condition receiving instructions that prescribed explicit movement form, and a NLP condition presented with analogy-based instructions and two task constraints. Both conditions completed seven lessons across 4-weeks. Results: There were no significant differences in the quantity of exploration, with both conditions demonstrating a similar range of movement patterns. These findings were coupled with a significant improvement in performance accuracy (reduced forward movement of the barbell; F × D) for both conditions. No significant differences were detected in the distribution of barbell trajectory types, with type one, three and four trajectories being exhibited to a similar degree in both conditions. Conclusion: Findings from this study suggests both NLP and LP pedagogies can successfully develop movement form based skills. Overall, both NLP and LP approaches appear to positively influence skill development. These findings have important implications for practitioners suggesting that deviations from instructed technique in learners (i.e., LP approach) do not negatively impact performance. However, further research is needed to determine whether these approaches can more effectively facilitate learners' search for movement solutions that "fit" their individual abilities.

Effects of a blended classroom-based intervention on aerobic fitness, motor skills, inhibition, and daytime sleepiness among Hong Kong children.

In response to the all-round development of primary school children, this study aimed to evaluate the effectiveness of a blended intervention program on children's health-related outcomes of aerobic fitness, motor skills, inhibition and daytime sleepiness in classroom settings. Three experimental conditions include: (1) the "Stand + Move" group combining sit-stand desks and physical activity (PA) recess, (2) "Move" group with PA recess only, and (3) Control group (CG; normal class schedule). A total of 64 primary school children (37.5% girls and 62.5% boys, M [SD] = 9.6 [0.61], BMI mean = 17.0 ± 3.0) participated in all assessments, including aerobic fitness, motor skills, inhibitory control, and daytime sleepiness. The baseline data collection starts from January 2019, with the intervention lasting for 13 weeks and followed by post-intervention and follow up tests conducted in July and October 2019. There was a significant interaction effect on aerobic fitness [F (2,76) = 10.62, p < 0.001, η2 = 0.22] after the intervention period, whereas no significant interaction was observed for other variables. Significant main effects were observed in aerobic fitness (pre - post: -11.75 and -7.22) for both experimental groups, with the blended group showing greater improvements immediately post the test, while motor skills only showed a significant increase at the three-month follow-up, with the greatest increase in the blended group (pre-follow-up: -2.50). For inhibition control and daytime sleepiness, better improvements were shown for the experimental groups than for the control group. The blended designed intervention, by incorporating multiple components as an innovative strategy to reconstruct children's traditional classroom environment in Hong Kong, has demonstrated improved physical and psychological development of school children. Clinical trial registration: ChiCTR, ChiCTR2000035038. Registered 29 July 2020 - Retrospectively registered. http://www.chictr.org.cn/hvshowproject.aspx?id=46038.

Nonlinear Dynamic Measures of Walking in Healthy Older Adults: A Systematic Scoping Review.

BACKGROUND: Maintaining a healthy gait into old age is key to preserving the quality of life and reducing the risk of falling. Nonlinear dynamic analyses (NDAs) are a promising method of identifying characteristics of people who are at risk of falling based on their movement patterns. However, there is a range of NDA measures reported in the literature. The aim of this review was to summarise the variety, characteristics and range of the nonlinear dynamic measurements used to distinguish the gait kinematics of healthy older adults and older adults at risk of falling. METHODS: Medline Ovid and Web of Science databases were searched. Forty-six papers were included for full-text review. Data extracted included participant and study design characteristics, fall risk assessment tools, analytical protocols and key results. RESULTS: Among all nonlinear dynamic measures, Lyapunov Exponent (LyE) was most common, followed by entropy and then Fouquet Multipliers (FMs) measures. LyE and Multiscale Entropy (MSE) measures distinguished between older and younger adults and fall-prone versus non-fall-prone older adults. FMs were a less sensitive measure for studying changes in older adults' gait. Methodology and data analysis procedures for estimating nonlinear dynamic measures differed greatly between studies and are a potential source of variability in cross-study comparisons and in generating reference values. CONCLUSION: Future studies should develop a standard procedure to apply and estimate LyE and entropy to quantify gait characteristics. This will enable the development of reference values in estimating the risk of falling.

A Randomized Controlled Trial of a Blended Physical Literacy Intervention to Support Physical Activity and Health of Primary School Children.

BACKGROUND: The concept of physical literacy (PL) has been advocated as the need to create environments fostering sustainable engagement in PA. This study adopted ecological approach to evaluate the effectiveness of a blended PL intervention embedded into the school day to support children's PA and health. METHOD: Designed as a three-arm randomized controlled trial, a total of 79 participants (59.5% girls) were randomly assigned to: the "Quantity + Quality" blended PL group combining sit-stand desks and play-based recess (SSPlay), the "Quality" group with play-based recess only (Play) or the control group. The intervention lasted for 13 weeks, and all the variables were collected at baseline, post-intervention and 3-month follow-up. RESULTS: SSPlay and Play group significantly improved on two of the embodied PL domains, Physical Competence (- 2.96 vs - 5.15, p < 0.05) and Knowledge and Understanding (- 2.35 vs - 2.00, p < 0.05), total errors of cognitive flexibility (24.00 vs 12.92, p < 0.05), and this difference was maintained at follow-up (p < 0.05). Whilst there was no interaction effect between groups, and time effects were found for PA and planning from baseline to post-intervention. CONCLUSION: This was the first to adopt an ecological approach as an innovative strategy to provide the emergence of PA for children in Hong Kong. The blended intervention design that embedded both quantity and quality of PA into children's school day has shown promise in supporting children's all round development. PL intervention where environments are designed to increase the "Quantity + Quality" of children's everyday interactions has led to improvements in PA and health outcomes, which may provide insights for future studies to adopt cost-friendly and feasible measures for promoting children's PA in the school settings. TRIAL REGISTRATION: ChiCTR, ChiCTR2000035038. Registered 29 July 2020-Retrospectively registered. http://www.chictr.org.cn/hvshowproject.aspx?id=46038 .

Validation of the Perception Neuron system for full-body motion capture.

Recent advancements in Inertial Measurement Units (IMUs) offers the possibility of its use as a cost effective and portable alternative to traditional optoelectronic motion capture systems in analyzing biomechanical performance. One such commercially available IMU is the Perception Neuron motion capture system (PNS). The accuracy of the PNS had been tested and was reported to be a valid method for assessing the upper body range of motion to within 5° RMSE. However, testing of the PNS was limited to upper body motion involving functional movement within a single plane. Therefore, the purpose of this study is to further validate the Perception Neuron system with reference to a conventional optoelectronic motion capture system (VICON) through the use of dynamic movements (e.g., walking, jogging and a multi-articular sports movement with object manipulation) and to determine its feasibility through full-body kinematic analysis. Validation was evaluated using Pearson's R correlation, RMSE and Bland-Altman estimates. Present findings suggest that the PNS performed well against the VICON motion analysis system with most joint angles reporting a RMSE of < 4° and strong average Pearson's R correlation of 0.85, with the exception of the shoulder abduction/adduction where RMSE was larger and Pearson's R correlation at a moderate level. Bland-Altman analysis revealed that most joint angles across the different movements had a mean bias of less than 10°, except for the shoulder abduction/adduction and elbow flexion/extension measurements. It was concluded that the PNS may not be the best substitute for traditional motion analysis technology if there is a need to replicate raw joint angles. However, there was adequate sensitivity to measure changes in joint angles and would be suitable when normalized joint angles are compared and the focus of analysis is to identify changes in movement patterns.

Teachers' Perceptions of Applying Contemporary Skill Acquisition Approaches in High School Physical Education.

Using contemporary skill acquisition approaches to skill learning appears to be a worthwhile pedagogical option for teachers and coaches in sports and Physical Education (PE). However, PE at the High School level in New Zealand has assessment components that are still underpinned by traditional and outdated skill learning theories. In response to this challenge, two motivated Heads of Department in PE undertook a department-wide professional development initiative to teach the national standard assessment via the use of a contemporary skill acquisition approach, which is student-centred, with an emphasis on enhancing exploratory learning and encouraging autonomy. Each department worked together over a 10-week period with a Higher Education specialist in skill acquisition to design and teach using contemporary skill acquisition approaches. Qualitative data was collected via semi-structured focus group interviews. Insightful data on the influence of teaching using contemporary skill acquisition approaches was acquired from the teachers in the two PE departments. It was found that substantial pedagogical practice changes were achieved by the teachers (e.g., less focus on ideal technique and more on varying the context). They also enjoyed the learning experience that the contemporary skill acquisition approach offered as compared to their previous experience of more traditional teaching approaches, which have a focus on knowledge acquirement with little opportunities for exploratory learning. In addition, from a practical perspective, teachers were observed to demonstrate greater engagement in professional conversations around learning and could see greater relevance in the transfer of learning in the use of contemporary skill acquisition approaches to other teaching contexts.

The Role of Nonlinear Pedagogy in Supporting the Design of Modified Games in Junior Sports.

Nonlinear Pedagogy has been advocated as an approach that views acquisition of movement skills with a strong emphasis on exploratory behaviors and the development of individualized movement skills. Underpinned by Ecological Dynamics, Nonlinear Pedagogy provides key ideas on design principles to support a teaching and learning approach that accounts for dynamic interactions among constraints in the evolution of movement behaviors. In the context of junior sports, the manipulation of task constraints is central to how games can be re-designed for children to play that are age and body appropriate so that the games can still capture the key elements of representativeness as compared to the adult form of the game. Importantly, these games offer suitable affordances that promote sensible play that could be transferable to other contexts. In this paper, we provide an in-depth discussion on how Nonlinear Pedagogy is relevant in supporting the design and development of modified games in the context of junior sports. Practical implications are also provided to share how games can be modified for meaningful play to emerge.

Perceptual-motor skill transfer: Multidimensionality and specificity of both general and specific transfers.

This paper aims to investigate perceptual-motor skill transfer, both through the specific as well as the general aspect of skill transfer. Specifically, we examined differences in skill transfer that occurred between participants who are skilled in practicing a perceptual motor activity involving striking with an implement and participants who are skilled in their own sports but are novice to striking task (i.e., batting an immobile ball). Skill transfer was assessed through the effect of practicing a new, novel task on the performance (ball velocity), intrinsic behavior (elbow and shoulder kinematic) as well as on the impetus for exploratory behavior (variability of elbow and shoulder kinematics) in the two groups of participants (n = 8 for each group), with reference to another group of expert participants (n = 8) for this batting task. Results showed that positive skill transfer was present and was multidimensional in the group of participants who have experience in using an implement in striking tasks. In addition, both specific transfer as well as general transfer were dependent on the task dynamics. More precisely, positive transfer was observed both through a sharing of similar movement patterns, an impetus for exploration and a direct transfer of performance in a novel task between groups who have experience in using an implement in striking tasks.

Acute effects of wearing compression knee-length socks on ankle joint position sense in community-dwelling older adults.

Functional proprioceptive information is required to allow an individual to interact with the environment effectively for everyday activities such as locomotion and object manipulation. Specifically, research suggests that application of compression garments could improve proprioceptive regulation of action by enhancing sensorimotor system noise in individuals of different ages and capacities. However, limited research has been conducted with samples of elderly people thus far. This study aimed to examine acute effects of wearing knee-length socks (KLS) of various compression levels on ankle joint position sense in community-dwelling, older adults. A total of 26 participants (12 male and 14 female), aged between 65 and 84 years, were randomly recruited from local senior activity centres in Singapore. A repeated-measures design was used to determine effects on joint position awareness of three different treatments-wearing clinical compression socks (20-30 mmHg); wearing non-clinical compression socks (< 20 mmHg); wearing normal socks, and one control condition (barefoot). Participants were required to use the dominant foot to indicate 8 levels of steepness (2.5°, 5°, 7.5°, 10°, 12.5°, 15°, 17.5°, and 20°), while standing on a modified slope box, in a plantar flexion position. Findings showed that wearing clinical compression KLS significantly reduced the mean absolute errors compared to the barefoot condition. However, there were no significant differences observed between other KLS and barefoot conditions. Among the KLS of various compression levels, results suggested that only wearing clinical compression KLS (20-30 mmHg) improved the precision of estimation of ankle joint plantar flexion movement, by reducing absolute performance errors in elderly people. It is concluded that wearing clinical compression KLS could potentially provide an affordable strategy to ameliorate negative effects of ageing on the proprioception system to enhance balance and postural control in community-dwelling individuals.

Anxiety on Quiet Eye and Performance of Youth Pistol Shooters.

In adults, longer quiet-eye (QE) durations have been associated with more successful sport performances and less deterioration in skill during anxiety-inducing situations. This study aimed to establish if QE patterns in youth are similar to those reported in adults. Ten youth shooters, age 13.13 ± 0.83 years, completed an air-pistol task under a control and an anxiety condition. Mixed-design 2 (performance outcome) × 2 (condition) ANOVA tests were conducted with two performance measures-objective and coach rated. No significant main or interaction effects were found. Unlike in adults, performance and anxiety did not differentiate QE duration in youth athletes, although QE duration was longer during good shots than poor shots across both performance measures, and the shortest durations were recorded during poor shots in the anxiety condition. This preliminary exploration encourages more research with youth athletes to determine the efficacy of QE patterns across different learners.

Reliability of a Novel Badminton Intermittent Exercise Protocol.

Purpose: Badminton is a sport characterized by high-intensity activity interspersed with short rests requiring specific physiological fitness, skills and game tactics. This study aimed to develop, describe and establish the reliability of a novel badminton intermittent exercise protocol, to simulate singles match-play (Part A) and assess match-fitness (Part B). Method: Twelve well-trained male badminton players performed a two-part protocol, mimicking the demands and activity of match-play, on two occasions with at least 72-h recovery. Part A imitated match-play and consisted of 40 stages alternating between 20 s work - receiving shuttlecocks from a launcher and ghosting (simulated) actions - and 40 s rest. Part B was an open-ended period, challenging match-fitness, designed to exhaust participants within 10 min. Physiological responses (heart rate, blood lactate and ratings of perceived exertion) (Part A and B) and time to exhaustion (Part B) were determined both times. Results: There were no differences in performance and physiological responses between trials (p > .05). The protocol demonstrated excellent reliability (intraclass correlation coefficient > 0.89) for all variables. Time to exhaustion (Part B) was 198 ± 98 s and 194 ± 82 s, respectively. Mean (Part A) and peak (Part B) heart rates were 166 ± 9; 191 ± 8 b∙min-1 and 166 ± 9; 191 ± 7 b∙min-1 and blood lactate concentrations (Part B) 11.8 ± 2.3 and 11.5 ± 2.1 mmol∙l-1 for trials 1 and 2, respectively. Conclusion: The protocol reliably induces match-like responses and can be used to assess match-fitness for training/research purposes.

Immediate effects of wearing knee length socks differing in compression level on postural regulation in community-dwelling, healthy, elderly men and women.

BACKGROUND: Stimulation of lower limbs' cutaneous receptors and mechanoreceptors through compression garments could potentially increase somatosensory system efficiency and aid postural regulation in elderly individuals. RESEARCH QUESTION: This study examined immediate effects of wearing knee length socks (KLS) of various compression levels on somatosensory function in community-dwelling healthy elderly men and women during a double-limb standing, balancing task. METHODS: A total of forty-six elderly participants (Male = 23), aged between 65 and 84 years old, randomly selected from the Singapore community-dwelling, healthy population. Three treatment interventions (wearing clinical compression socks; wearing non-clinical compression socks; wearing commercial socks) and one control condition (barefoot), in a counterbalanced order, were administered to participants while they performed a 30-s Romberg test, with four levels of performance difficulty: (1) standing on a stable surface with vision (SO); (2) a stable surface without vision (SC); (3) a foam surface with vision (FO); and (4), a foam surface without vision (FC). RESULTS: Results showed that immediate effects of applying KLS of various compression levels significantly reduced sway area, trace length, velocity, and anterior-posterior (AP) sway as compared to barefoot condition (control) during the FO task condition. SIGNIFICANCE: This finding indicates the positive immediate effects of garments on somatosensory system function and postural regulation in the elderly men and women, especially when standing on the unstable surface. Wearing compression KLS could be included as a viable intervention on top of other forms of balance training to reduce risk of falling in elderly people.

Behavioral Repertoire Influences the Rate and Nature of Learning in Climbing: Implications for Individualized Learning Design in Preparation for Extreme Sports Participation.

Extreme climbing where participants perform while knowing that a simple mistake could result in death requires a skill set normally acquired in non-extreme environments. In the ecological dynamics approach to perception and action, skill acquisition involves a process where the existing repertoire of behavioral capabilities (or coordination repertoire) of a learner are destabilized and re-organized through practice-this process can expand the individuals affordance boundaries allowing the individual to explore new environments. Change in coordination repertoire has been observed in bi-manual coordination and postural regulation tasks, where individuals begin practice using one mode of coordination before transitioning to another, more effective, coordination mode during practice. However, individuals may also improve through practice without qualitatively reorganizing movement system components-they do not find a new mode of coordination. To explain these individual differences during learning (i.e., whether or not a new action is discovered), a key candidate is the existing coordination repertoire present prior to practice. In this study, the learning dynamics of body configuration patterns organized with respect to an indoor climbing surface were observed and the existing repertoire of coordination evaluated prior to and after practice. Specifically, performance outcomes and movement patterns of eight beginners were observed across 42 trials of practice over a 7-week period. A pre- and post-test scanning procedure was used to determine existing patterns of movement coordination and the emergence of new movement patterns after the practice period. Data suggested the presence of different learning dynamics by examining trial-to-trial performance in terms of jerk (an indicator of climbing fluency), at the individual level of analysis. The different learning dynamics (identified qualitatively) included: continuous improvement, sudden improvement, and no improvement. Individuals showing sudden improvement appeared to develop a new movement pattern of coordination in terms of their capability to climb using new body-wall orientations, whereas those showing continuous improvement did not, they simply improved performance. The individual who did not improve in terms of jerk, improved in terms of distance climbed. We discuss implications for determining and predicting how individual differences can shape learning dynamics and interact with metastable learning design.

Pre-movement and during-movement visual search behaviours vary depending on expertise and anxiety levels in ten-pin bowling.

This study investigated the pre-movement and during-movement visual search behaviour (VSB) and quiet eye (QE) of 11 elite versus 10 sub-elite ten-pin bowlers, performing under high-anxiety and low-anxiety conditions. Pre-movement and independent of expertise, bowlers had more fixations and directed them to more locations when performing under high-anxiety compared with low-anxiety. Elite bowlers fixated at more locations closer to the pins in pre-movement than during-movement, with pre-movement QE occurring mostly at the breakpoint and middle arrows. During movement however, bowlers fixated closer to the foul-line at the middle and right dots and arrows, with during-movement-QE occurring at the middle dots and right arrows. Elite bowlers recorded longer QE durations during-movement rather than pre-movement, albeit a later onset during the longish five-step approach prior to ball release compared with sub-elite bowlers. Our results suggest that QE during-movement instead of pre-movement could be more pertinent in differentiating expertise during sporting tasks with a long movement phase and far-aiming target. The relevance of pre-movement or movement-QE in characterising expertise and performance could therefore be sport-dependent. This should be considered when investigating skilled action and developing training programs for skill acquisition.

Children's perception of action boundaries and how it affects their climbing behavior.

There are some concerns that children today may be less calibrated to their action capabilities because of the "risk-free" culture that has proliferated during recent decades. This study investigated the extent to which judgments of reaching affordances presented in different directions (i.e., overhead, diagonal, and horizontal) are related to children's climbing behavior on a climbing wall. A sample of 30 schoolchildren from 6 to 11years old (20 boys and 10 girls) estimated maximum reach and grasp distances and subsequently attempted to climb across an indoor climbing wall. Children who perceived the extents of their reach more accurately completed the climb more often and more quickly. Judgments in the primary directions of climbing locomotion (horizontal and diagonal) were better predictors of success than vertical judgments. Judgments about whether objects are reachable and graspable are complex and influenced by various dynamic factors (including perceptual-motor calibration), and as such different levels of accuracy are likely in different reaching directions. It appears that young children are relatively sensitive to their action boundaries for climbing and, therefore, may be able to make informed decisions themselves about whether a surface is climbable.

Effects of Caffeine Supplementation on Performance in Ball Games.

Although a large body of evidence exists documenting the ergogenic properties of caffeine, most studies have focused on endurance performance. However, findings from endurance sports cannot be generalized to performance in ball games where, apart from having a high level of endurance, successful athletic performances require a combination of physiological, technical and cognitive capabilities. The purpose of this review was to critically evaluate studies that have examined the effect of a single dose of caffeine in isolation on one or more of the following performance measures: total distance, sprint performance, agility, vertical jump performance and accuracy in ball games. Searches of three major databases resulted in 19 studies (invasion games: 13; net-barrier games: 6) that evaluated the acute effects of caffeine on human participants, provided the caffeine dose administered, and included a ball games specific task or simulated match. Improvements in sprint performance were observed in 8 of 10 studies (80%), and vertical jump in 7 of 8 studies (88%). Equivocal results were reported for distance covered, agility and accuracy. Minor side effects were reported in 4 of 19 studies reviewed. Pre-exercise caffeine ingestion between 3.0 and 6.0 mg/kg of body mass appears to be a safe ergogenic aid for athletes in ball games. However, the efficacy of caffeine varies depending on various factors, including, but not limited to, the nature of the game, physical status and caffeine habituation. More research is warranted to clarify the effects of caffeine on performance measures unique to ball games, such as agility and accuracy. It is essential that athletes, coaches and practitioners evaluate the risk-benefit ratio of caffeine ingestion strategies on an individual case-by-case basis.