Applying the constraints-led approach to facilitate exploratory learning of the volleyball serve.

Exploration is an important feature for successfully learning motor skills. However, game rules such as one attempt to serve in volleyball could discourage exploration due to an individual's fear of making a mistake and forfeiting a point. The constraints-led approach is a coaching methodology that encourages exploration by selectively manipulating task constraints such as rules. Therefore, the aim of this study was to examine whether the addition of the task constraint of a second serve would encourage volleyball players to use their first serve to explore their action capabilities. Forty male high school students competed in two volleyball games; a regulation (single serve) game and a modified (2-serve) game. Participants reported that having a second chance at serving allowed them to feel more confident and relaxed which facilitated the exploration of their serving capability. In the 2-serve game, participants attempted a more powerful (M = 60.3 km/hr), and complex (M = 44.5% jump topspin serves) first serve, compared to the regulation game (M = 55.6 km/hr; M = 25.2% jump topspin serves). Findings suggest that to facilitate learning of motor skills, it is important to manipulate the practice environment using task constraints to address the factors that restrict exploration.

XR Programmers Give Their Perspective on How XR Technology can be Effectively Utilised in High-Performance Sport.

BACKGROUND: The successful use of extended reality (XR) in sport is highly dependent on the extent to which it can represent the perception-action couplings that exist in the performance setting. However, there are many unknowns regarding the effectiveness of XR technology which is limiting its adoption in sport. Therefore, providing high-performance sporting organisations with more information about the efficacy and utility of XR, specifically its strengths and limitations, is warranted. RESULTS: The results provide insight into the limitations of XR and how those limitations are likely to reduce the effectiveness of XR for training motor skills. The participants described opportunities provided by XR for measuring athlete performance and highlighted several practical applications for enhancing athlete and coaching performance. Using artificial intelligence (AI) for training tactical decision-making and creating new movement solutions was also a key finding. CONCLUSIONS: The use of XR in sport is in its infancy, and more research is required to establish a deeper understanding of its utility and efficacy. This research provides sporting organisations, coaches, athletes, and XR technology companies with insights into where XR technology can have the greatest positive impact on performance in sport.

Previous experiences can influence individual cricket spin bowlers' perceptions of affordances in the performance landscape.

The ecological dynamics framework emphasises that movement solutions are guided by the relationship that exists between the performer and their environment, scaled to an individual's own action capabilities. This suggests that representative practice tasks should be used in high performance settings to encourage individually optimised movement solutions for both team and individual sports. This study specifically focuses on individual cricket spin bowlers and aims to understand the influence of their prior learning experiences on their perceptual attunement strategies when tasked with performing on a familiar Australian cricket pitch and a less familiar bespoke international (Indian) pitch. Two right hand leg spin bowlers that were part of a group of eight emerging expert spin bowlers were chosen for individual analysis. Bowler A reported 80 prior experiences of bowling on subcontinental (i.e., India, Pakistan, or Bangladesh) pitches whereas Bowler B had only 20 prior experiences. Overall, both bowlers' outcome performances either met or exceeded their expectations. Bowler A chose to calibrate his bowling style on the less familiar pitch to improve the fit between his delivery characteristics and the environmental pitch conditions, whereas Bowler B maintained his bowling style, even though he recognised a difference in the pitch conditions. Therefore, Bowler A maintained stable performance outcomes by implementing flexible movement solutions. In contrast, while Bowler B achieved his expected performance outcomes, his lack of diverse learning experiences may limit his action capabilities, although more performance trials are needed to confirm this conclusion. Regardless, this study demonstrates that there is valuable information in knowing how a player achieves a successful result, which should be coupled with performance outcomes to help create individualised development strategies.

The Communication and Passing Contributions of Playing Positions in a Professional Soccer Team.

Determining the connectivity of team members in sport provides important information on team functioning. In soccer, teams that are highly connected via passing have been shown to be more successful compared to teams less connected via passing. In addition to passing connectivity, players are connected with each other via intra-team communication (ITC) through verbal instruction, and nonverbal cues. Despite ITC being a known component of effective teamwork to enhance strategy, efficiency, motivation and concentration, ITC of individual playing positions has not previously been measured during soccer games, nor has it been associated with passing connections in a performance context. In this study, the received ITC that was perceived to be beneficial to performance during 22 competitive professional soccer matches was measured, in conjunction with the passing connections between team members. In total, 526 ITC ratings were collected and analysed, and a total of 7,693 passes were analysed. From the ITC and passing measures, a player connectivity index (PCI) representing the coupling of ITC and passing, was developed to determine the overall connectivity of the individual playing positions. Social network analysis (SNA) centrality metrics were used to determine the connectivity of the playing positions. There were significant (p < .05) main effects between playing positions for beneficial ITC, passing, and the PCI for centrality metrics, indicating that different playing positions interact with other team members differently. Pairwise comparisons indicated significant differences between individual playing positions for ITC, passing and the PCI. The two central defenders and the two central defensive midfielders had the highest mean values for ITC, passing, and the PCI compared to the other playing positions. The current findings suggest that central defenders and central defensive midfielders are positioned tactically to be highly involved in the build-up of passing moves, and to deliver beneficial task related information to team members. These findings have implications for performance analysis, coaches, and for talent identification.

Skilled swimmers maintain performance stability under changing attentional focus constraints.

Focusing attention externally, rather than internally, has generally proved advantageous as it avoids interfering with self-organzing processes. However, some research has suggested that this may not necessarily be the case with highly skilled individuals who by definition possess a greater capacity to either adapt or maintain stability under varied task constraints. This study aimed to address this gap by comparing the performance of skilled athletes under internal and external attentional focus conditions using the swimming dive start as a task vehicle. Using a counterbalanced repeated measures design, skilled swimmers performed dive starts in conditions of differing attentional focus - internal and external attentional focus. Kinetic and kinematic variables were collected and statistical analyses conducted to compare differences between conditions. The results revealed no differences in outcome performance (relative peak power, horizontal velocity, and time to 5 m) between internal and external focus conditions. However, remaining kinematic and kinetic measures revealed that all movement events occurred earlier in the movement sequence, suggesting superior self-organization of movement in the external focus condition. An external focus may be beneficial for the organization of movement control in skilled swimmers, but may not have an immediate impact upon the outcome of the task.

Lower-Body Aquatic Training Prescription for Athletes.

ABSTRACT: Holmberg, PM, Gorman, AD, Jenkins, DG, and Kelly, VG. Lower-body aquatic training prescription for athletes. J Strength Cond Res 35(3): 859-869, 2021-Traditionally prescribed to manage various medical ailments and promote healing, aquatic immersion may provide a favorable environment to undertake preparatory training tasks given its profound biological effects that extend across most homeostatic systems. In addition to understanding these effects, which are related to the fundamental principles of hydrodynamics, there is a need to consider the acute physiomechanical responses to alterations of key constraints associated with particular preparatory tasks. Evidence suggests that the manipulation of different constraints during aquatic training can enable a unique setting to complement, supplement, or supplant land-based programming to maintain or improve physical capacities in athletes without exacerbating physiological stress. Thus, this article focuses on the interplay of constraints and their associated outcomes to provide information that can be used to program lower-body aquatic training for athletes. In addition, the aim of the article is to summarize the literature on aquatic training to highlight the outcomes that occur when certain constraints are manipulated.

Bayesian hierarchical modelling of basketball tracking data - a case study of spatial entropy and spatial effectiveness.

Spatio-temporal data in sport is increasing rapidly, however suitable statistical methods for analysing this data are underdeveloped. The current study establishes the need for spatial statistical methods, propose a Bayesian hierarchical model as an appropriate method for comparing spatial variables, and test this model across three spatial scales. The need for spatial statistical methods was established through the identification of spatial autocorrelation. This necessitated the use of a Bayesian hierarchical model to test for an association between spatial ball movement entropy and spatial effectiveness. Posterior distribution results showed a generally positive association such that increases in entropy were associated with increases in effectiveness. The strength and confidence of the associations were impacted by the spatial scale, with the 6 × 6 grid showing the most conclusive evidence of a positive relationship; the 4 × 4 grid was mostly positive, however with a large variation; and finally, the basket-centric scale results were less conclusive. The results of the current study demonstrate the suitability of a Bayesian hierarchical model for testing for associations or differences between spatial variables. With the increase in spatial analyses in sport, this study presents an appropriate statistical method for dealing with complex problems associated with spatial analyses.

Do the landing mechanics of experienced netball players differ from those of trained athletes competing in sports that do not require frequent landings?

OBJECTIVES: This study examined whether young (15-19 years old) high-performance netball players exhibit different landing mechanics compared to female controls who do not participate in sports requiring frequent landings. DESIGN: Comparative, cross-sectional. METHODS: Lower limb kinematics and kinetics from 23 youth high performance female netball players (age: 17.5±1.7 years, height: 1.77±0.06m, mass: 66.5±6.33kg, netball experience: 8.5±2.3 years) were compared to data from 23 females (age: 22.0±3.2 years, height: 1.70±0.05m, mass: 64.4±6.7kg) who were involved in competitive sport, but had minimal experience playing a jump-landing sport. The jump landing task required participants to perform a countermovement jump and grab a netball suspended at 85% of the participant's maximum jump height. On random trials the ball was raised rapidly to 100% maximum jump height as the participant initiated her jump. RESULTS: The netball group landed with significantly less contribution from the knee extensors to total work for the non-preferred leg (P<0.001, ds=1.10) than the inexperienced group. Although no other significant differences were found between groups, there were several small to moderate differences in several of the key biomechanical variables identified as being risk factors for ACL injury or associated with ACL strain. CONCLUSIONS: Both groups had similar knee valgus and internal rotation angles and moments, with nearly all participants presenting with relatively poor frontal plane knee control. Overall, results suggest that experience playing a netball may not be enough to develop low-risk landing mechanics.

Examining environmental constraints in sport: Spin characteristics of two cricket pitches with contrasting soil properties.

In the sport of cricket, the pitch is an organic surface that represents an important environmental constraint. While the soil properties of the pitch are known to influence the pace and bounce of medium and fast deliveries, it is unknown how the soil constructs or the seam of the cricket ball affect the pace, bounce, and deviation of a spinning delivery. A specialised spin bowling machine was used to deliver 276 (139 wrist spin, 137 finger spin) spinning deliveries onto two cricket pitches with contrasting soil properties. The pitches included a bespoke international pitch (BIP; higher sand content at 43.28%) and a common Australian pitch (CAP; lower sand content at 7.44%). Results indicated that the BIP showed significantly slower reflection pace and larger deviation, compared to the CAP. Irrespective of the pitch type, when the seam of the ball impacted the pitch, there was a significantly slower reflection pace and larger deviation. The reflection properties of the BIP resembled that of a "spinning pitch" which can be used as a form of representative practice for conditions similar to those that may be experienced in India. The impact of the seam on the pitch surface significantly altered the reflection of the ball and should be considered in future cricket research.

Exploring the Justifications for Selecting a Drop Landing Task to Assess Injury Biomechanics: A Narrative Review and Analysis of Landings Performed by Female Netball Players.

When assessing biomechanics in a laboratory setting, task selection is critical to the production of accurate and meaningful data. The injury biomechanics of landing is commonly investigated in a laboratory setting using a drop landing task. However, why this task is so frequently chosen is unclear. Therefore, this narrative review aimed to (1) identify the justification/s provided within the published literature as to why a drop landing task was selected to investigate the injury biomechanics of landing in sport and (2) use current research evidence, supplemented by a new set of biomechanical data, to evaluate whether the justifications are supported. To achieve this, a comprehensive literature search using Scopus, PubMed, and SPORTDiscus online databases was conducted for studies that had collected biomechanical data relating to sport injuries using a drop landing task. In addition, kinematic and kinetic data were collected from female netball players during drop landings and maximum-effort countermovement jumps from the ground to grab a suspended ball. The literature search returned a total of 149 articles that were reviewed to determine the justification for selecting a drop landing task. Of these, 54% provided no explicit justification to explain why a drop landing task was chosen, and 15% stated it was selected because it had been used in previous research. Other reasons included that the drop landing provides high experimental control (16%), is a functional sports task (11%), and is a dynamic task (6%). Evidence in the literature suggests that the biomechanical data produced with drop landings may not be as externally valid as more sport-specific tasks. Biomechanical data showed that the drop landing may not control center of mass fall height any better than maximum-effort countermovement jumps from the ground. Further, the frequently used step-off technique to initiate drop landings resulted in kinematic and kinetic asymmetries between lower limbs, which would otherwise be symmetrical when performing a countermovement jump from the ground. Researchers should consider the limitations of a drop landing task and endeavor to improve the laboratory tasks used to collect biomechanical data to examine the injury biomechanics of landing.

Beyond the Tip of the Iceberg: Using Systems Archetypes to Understand Common and Recurring Issues in Sports Coaching.

Background: Systems thinking, a fundamental approach for understanding complexity, is beginning to gain traction in sports science. Systems archetypes (SAs) describe common recurring patterns of system behaviors and have been used extensively in other domains to explain the system wide influences on behavior. SAs look at the deeper levels of systemic structure by identifying what creates system behaviors, which supports the development of interventions to identify and resolve problem sources. Methods: Four commonly used SAs were used to explain the dynamics underpinning recurring issues for coaching in football: (1) Fixes that fail, (2) Shifting the burden, (3) Drifting goals, and (4) Success to the successful. The SAs models were built, refined and validated by seven subject matter experts (SMEs) including experienced football researchers, systems thinking experts, an international football coach, a skill acquisition specialist, and an experienced exercise scientist. Results: The findings show that the SAs fit well in the football coaching context, providing further evidence that a complex system thinking approach is required when considering football performance and its optimization. The developed SAs identify the factors that play a role in recurring issues in football coaching and highlight the systemic structures that contribute to the issues. The developed SAs identify the appropriate leverage points in the system where sustainable change can be made to improve coaching practice and subsequent performance of players. Discussion: A common theme emerging across the analyses was that systemic problems often arise in football when quick fixes are attempted. Whereas, improvements to system behavior usually require a delay after the implementation of the appropriate corrective action. The SAs developed in the current study also provide practical templates of common problems in football that can be used to prompt discussions around how to avoid ineffective interventions and instead make sustainable improvements across multiple aspects of football performance.

Inorganic Triphenylphosphine.

A completely inorganic version of one of the most famous organophosphorus compounds, triphenylphosphine, has been prepared. A comparison of the crystal structures of inorganic triphenylphosphine, PBaz3 (where Baz=B3 H2 N3 H3 ) and PPh3 shows that they have superficial similarities and furthermore, the Lewis basicities of the two compounds are remarkably similar. However, their oxygenation and hydrolysis reactions are starkly different. PBaz3 reacts quantitatively with water to give PH3 and with the oxidizing agent ONMe3 to give the triply-O-inserted product P(OBaz)3 , an inorganic version of triphenyl phosphite; a corresponding transformation with PPh3 is inconceivable. Thermodynamically, what drives these striking differences in the chemistry of PBaz3 and PPh3 is the great strength of the B-O bond.

A social network analysis of the goal scoring passing networks of the 2016 European Football Championships.

In the current study, social network analysis (SNA) and notational analysis (NA) methods were applied to examine the goal scoring passing networks (GSPN) for all goals scored at the 2016 European Football Championships. The aim of the study was to determine the GSPN characteristics for the overall tournament, between the group and knock out stages, and for the successful and unsuccessful teams. The study also used degree centrality (DC) metrics as a novel method to determine the relative contributions of the pitch locations involved in the GSPN. To determine changes in GSPN characteristics as a function of changing score line, the analysis considered the match status of the game when goals were scored. There were significant differences for SNA metrics as a function of match status, and for the DC metrics in the comparison of the different pitch locations. There were no differences in the SNA metrics for the GSPN between teams in the group and knock out stages, or between the successful and unsuccessful teams. The results indicate that the GSPN had low values for network density, cohesion, connections, and duration. The networks were direct in terms of pitch zones utilised, where 85% of the GSPN included passes that were played within zones or progressed through the zones towards the goal. SNA and NA metrics were significantly different as a function of changing match status. The current study adds to the previous research on goal scoring in football, and demonstrates a novel method to determine the prominent pitch zones involved in the GSPN. These results have implications for match analysis and the coaching process.

Reduced attentional focus and the influence on expert anticipatory perception.

The anticipatory memory encodings of expert and novice basketball players were examined under conditions of both full (attended condition) and reduced (unattended condition) attention (see also Gorman, Abernethy, & Farrow in Attention, Perception, & Psychophysics, 75, 835-844, 2013a). Participants completed a typical pattern recall task using dynamic playing sequences from basketball, and their responses were compared to both the original target pattern as well as to the series of patterns that occurred immediately after and immediately before the target image. The latter had not previously been employed in a pattern recall task when examining the anticipatory encoding of pattern information. Results revealed that the overall extent of the forward displacement for both the attended and unattended patterns was generally significantly greater for the experts, with the expert advantage tending to be most prominent for the attacking patterns. The novel addition of both forward and backward scenes may provide a more precise measure of the anticipatory effect, suggesting that future research in this domain should use a similar methodological design.

What's in a game? A systems approach to enhancing performance analysis in football.

PURPOSE: Performance analysis (PA) in football is considered to be an integral component of understanding the requirements for optimal performance. Despite vast amounts of research in this area key gaps remain, including what comprises PA in football, and methods to minimise research-practitioner gaps. The aim of this study was to develop a model of the football match system in order to better describe and understand the components of football performance. Such a model could inform the design of new PA methods. METHOD: Eight elite level football Subject Method Experts (SME's) participated in two workshops to develop a systems model of the football match system. The model was developed using a first-of-its-kind application of Cognitive Work Analysis (CWA) in football. CWA has been used in many other non-sporting domains to analyse and understand complex systems. RESULT: Using CWA, a model of the football match 'system' was developed. The model enabled identification of several PA measures not currently utilised, including communication between team members, adaptability of teams, playing at the appropriate tempo, as well as attacking and defending related measures. CONCLUSION: The results indicate that football is characteristic of a complex sociotechnical system, and revealed potential new and unique PA measures regarded as important by SME's, yet not currently measured. Importantly, these results have identified a gap between the current PA research and the information that is meaningful to football coaches and practitioners.

The Effect of Recovery Duration on Vastus Lateralis Oxygenation, Heart Rate, Perceived Exertion and Time Motion Descriptors during Small Sided Football Games.

PURPOSE: Small sided games (SSG) of football are an effective and efficient format to simultaneously train the physiological, technical, and tactical components of football. The duration of the recovery period between bouts of SSG will affect the physiological response to subsequent bouts. It was hypothesised that decreasing the duration of recovery periods separating serial SSG bouts would increase physiological, and perceptual responses, and decrease high speed running, and distance during SSG bouts. METHODS: Twelve experienced footballers (mean ± SD; age 21 ± 3 yrs; VO2peak 64 ± 7 ml·min·kg-1; playing experience 15 ± 3 yrs) completed two SSG sessions. Each SSG consisted of 3 vs. 3 players and 6 bouts of 2 min duration, with bouts separated by either 30 s recovery (REC-30) or 120 s recovery (REC-120). Deoxygenated haemoglobin (HHb) in the vastus lateralis (VL) (using near infrared spectroscopy), heart rate (HR) and time motion descriptors (TMD) (speed and distance) were measured continuously during the SSG sessions and perceived exertion (RPE) was measured for each bout. RESULTS: During the recovery periods, in REC-30 compared to REC-120, there was a significant (p < 0.05) main effect of a higher HHb and HR. During the bouts, in REC-30 compared to REC-120, there were no significant differences in HHb, HR, RPE, or TMD, but within both REC-30 and REC-120 there were significant increases as a function of bout number in RPE. CONCLUSIONS: Although a four-fold increase in recovery period allowed a significant increase in the recovery of HHb and HR, this did not increase the physiological, and perceptual responses, or time motion descriptors during the bouts. These results could have been due to the regulation of effort (pacing), in these experienced players performing an exercise task to which they were well adapted.

Mechanisms of anterior cruciate ligament injuries in elite women's netball: a systematic video analysis.

This study involved a systematic video analysis of 16 anterior cruciate ligament (ACL) injuries sustained by elite-level netball players during televised games in order to describe the game situation, the movement patterns involved, the player's behaviour, and a potential injury mechanism. Eight of the ACL injuries were classified as "indirect contact" and eight as "non-contact". Two common scenarios were identified. In Scenario A the player was jumping to receive or intercept a pass and whilst competing for the ball experienced a perturbation in the air. As a result the player's landing was unbalanced with loading occurring predominantly on the knee of the injured side. In Scenario B the player was generally in a good position at ground contact, but then noticeably altered the alignment of the trunk before the landing was completed. This involved rotating and laterally flexing the trunk without altering the alignment of the feet. Apparent knee valgus collapse on the knee of the injured side was observed in 3/6 Scenario A cases and 5/6 Scenario B cases. Players may benefit from landing training programmes that incorporate tasks that use a ball and include decision-making components or require players to learn to cope with being unbalanced.

The Effect of Recovery Duration on Technical Proficiency during Small Sided Games of Football.

The aim of this study was to determine the effect of increasing the duration of the recovery periods separating serial bouts of small sided games (SSG) of football on technical skills (TS). Twelve semi-professional footballers (mean ± SD; age 21 ± 3 years; VO2peak 64 ± 7 mL∙min∙kg-1; playing experience 15 ± 3 years) completed two SSG sessions, consisting of 3 vs. 3 players and 6 bouts of 2 min, separated by either 30 s recovery (REC-30) or 120 s recovery (REC-120). Sixteen TS, including passing, possession, and defensive related variables, and exercise intensity (heart rate, rating of perceived exertion, time motion descriptors) during the bouts were measured. Repeated measures ANOVA were used to determine differences between-conditions, for TS. The number of successful tackles was significantly higher, and the average time each team maintained possession was significantly lower in REC-120 compared to REC-30. There were no significant differences for all other TS variables, or exercise intensity measures between REC-30 and REC-120. Overall, a four-fold increase in the duration of recovery separating SSG bouts did not alter the technical skill execution of players. The experience and skill level of the players, combined with an apparent regulation of effort through pacing, may have assisted in the maintenance of technical skill execution.

Evidence of different underlying processes in pattern recall and decision-making.

The visual search characteristics of expert and novice basketball players were recorded during pattern recall and decision-making tasks to determine whether the two tasks shared common visual-perceptual processing strategies. The order in which participants entered the pattern elements in the recall task was also analysed to further examine the nature of the visual-perceptual strategies and the relative emphasis placed upon particular pattern features. The experts demonstrated superior performance across the recall and decision-making tasks [see also Gorman, A. D., Abernethy, B., & Farrow, D. (2012). Classical pattern recall tests and the prospective nature of expert performance. The Quarterly Journal of Experimental Psychology, 65, 1151-1160; Gorman, A. D., Abernethy, B., & Farrow, D. (2013a). Is the relationship between pattern recall and decision-making influenced by anticipatory recall? The Quarterly Journal of Experimental Psychology, 66, 2219-2236)] but a number of significant differences in the visual search data highlighted disparities in the processing strategies, suggesting that recall skill may utilize different underlying visual-perceptual processes than those required for accurate decision-making performance in the natural setting. Performance on the recall task was characterized by a proximal-to-distal order of entry of the pattern elements with participants tending to enter the players located closest to the ball carrier earlier than those located more distal to the ball carrier. The results provide further evidence of the underlying perceptual processes employed by experts when extracting visual information from complex and dynamic patterns.

The expert advantage in dynamic pattern recall persists across both attended and unattended display elements.

We examined how differences in attention influence how expert and novice basketball players encode into memory the specific structural information contained within patterns of play from their sport. Our participants were primed during a typical recall task to focus attention on either attacking or defending player formations before being asked to recall the attended or unattended portion of the pattern. Adherence to the instructional set was confirmed through an analysis of gaze distributions. Recall performance was superior for the experts relative to the novices across both the attended and unattended attacking and defensive pattern structures. Expert recall of attacker positions was unchanged with and without attention, whereas recall accuracy for the positions of defenders diminished without attention, as did the novices' recall of both attack and defense formations. The findings suggest that experienced performers are better than novices at encoding the elements from a complex and dynamic pattern in the absence of focused attention, with this advantage being especially evident in relation to the recall of attacking structure. Some revision of long-term memory theories of expertise will be necessary to accommodate these findings.