ACUTE EFFECTS OF TECHNICAL INSTRUCTIONS ON SPRINT ACCELERATION TECHNIQUE AND PERFORMANCE

This study investigated the acute effect of verbal technical instructions intended to alter attentional focus during a 10 m sprint. Team sports athletes (n = 15) completed maximal effort sprints under a control condition and two experimental conditions: internal and external focus. Lower-body kinematic and external kinetic data were collected near the 5 m mark. Total sprint time was longer in both experimental conditions than the control condition (p < 0.05). Both experimental conditions altered ankle and knee angles at touchdown and led to more vertically oriented ground reaction forces (all p < 0.05). Whilst these instructions were detrimental to performance, the results support the importance of technical ability for sprint acceleration. Future studies should seek to identify instructions, potentially used within training programmes, which could be beneficial to performance

Hot hands, cold feet? Investigating effects of interacting constraints on place kicking performance at the 2015 Rugby Union World Cup

Place kicks in Rugby Union present valuable opportunities to score points outside the spatiotemporal dynamics of open play but are executed under varying performance constraints. We analysed effects of specific task constraints and relevant contextual factors on place kick performance in the 2015 Rugby Union World Cup. Data were collected from television broadcasts for each place kick. In addition to kick outcomes, contextual factors, including time of the kick in the match, score margin at the time of the kick, and outcome of the kicker’s previous kick, were recorded. Effects of spatial task constraints were analysed for each kick, using distance (m) and angle (°) of the kick to the goalposts. A binomial logistic regression model revealed that distance from, and angle to, the goalposts were significant predictors of place kick outcome. Furthermore, the success percentage of kickers who missed their previous kick was 7% lower than those who scored their previous kick. Place kick success percentage in the 10 minutes before half-time was 8% lower than the mean tournament success percentage, which was 75% (95% CI 71% to 78%). The highest kick success percentage was recorded when scores were level (83%; 95% CI 72% to 91%). Our data highlighted how subtle changes in task constraints and contextual factors can influence performance outcomes in elite performers in international competition. Fluctuations in place kick success suggested that individual constraints, such as thoughts, emotions, and fatigue, induced during competition, could interact with perceptions to influence emergent performance behaviours

PROXIMAL AND DISTAL CONSTRAINTS REDUCE DIMENSIONALITY OF VERTICAL JUMPING TASKS

The purpose of this study was to examine motor control strategies employed to control the degrees of freedom when performing a lower limb task with constraints applied at the hip, knee and ankle. Thirty-five individuals performed vertical jumping tasks: hip flexed, no knee bend and plantar flexed. Joint moment data from hip, knee and ankle was analysed using principal component analysis (PCA). In all, PCA performed, a minimum of two and maximum of six principal components (PCs) were required to describe the movement. A proximal to distal reduction in variability was only observed for the hip flexed and no knee bend conditions. Collectively, the results suggest a reduction in the dimensionality of the movement occurs, despite the constraints imposed within each condition and would suggest dimensionality reduction and motor control strategies are a function of the task demands

Experiential knowledge of elite Rugby Union players on key performance constraints in place kicking

There has been a growing tendency in sport science research to examine the relationship between empirical knowledge developed in scientific experiments and theoretical frameworks and the experiential knowledge of elite performers and practitioners (Jones, Bezodis, & Thompson, 2009; Greenwood, Davids, & Renshaw, 2014; Phillips, Davids, Renshaw, & Portus, 2014). In this study, we investigated the experiential knowledge of elite Rugby Union place kickers to access their understanding of how to satisfy interacting constraints of competitive performance and practice environments. Place kicks in Rugby Union offer opportunities to score points outside the spatiotemporal dynamics of open play, but are typically performed under varying task and contextual constraints within a performance environment. Success percentage of place kicks can fluctuate under specific task and contextual constraints, as shown in a recent analysis of the 2015 Rugby World Cup (Pocock, Bezodis, Davids, & North, under review). For example, success percentage can drop sharply at critical thresholds of distance and angle to the goalposts and can vary depending on time elapsed, score margin and previous kick success. Interestingly, place kicks in the 10 minutes before half time were 8% less successful than the tournament average, and place kickers who had missed their previous kick were 7% less successful than place kickers who had scored their previous kick. It has therefore been speculated that emotions induced during competition can interact with perceptions and action to influence the emergent behaviours of place kickers. To develop greater understanding of how fluctuations in performance data may emerge, we interviewed professional Rugby Union place kickers and sought to explore their experiences of satisfying key interacting constraints on performance. Specifically, we aimed to investigate the key constraints that place kickers perceive to influence their emotions and perceptions of task difficulty. A secondary aim of the interviews was to identify specific details of how place kicking situations are currently practised, and why they are structured in this way. We present here the experiential knowledge of place kickers which includes their perceptions of the key constraints in performance environments and how they currently prepare for place kicks. Our findings highlighted how performance constraints can influence emotions, cognitions and perceptions during place kicking performance and the data indicated how the key constraints identified in this study, combined with the findings of previous quantitative analyses, could be represented in training environments. Initial interviews revealed that place kicking is predominantly practised individually and in isolation from game-based scenarios in training, without any form of pressure or expectation. Examples of pressure that place kickers identified in interviews included expectations of team-mates, performing in front of large crowds and closely-matched scores. This presentation will conclude by discussing how an integration of empirical and experiential knowledge can enrich understanding of sport performance and provide recommendations for coaches when designing practice environments which simulate relevant performance constraints to enhance the adaptive skills of elite and developing athletes in sport

Theoretical and methodological aspect of the problem of development and support for talented pre-schoolers

В статье представлен анализ ведущих отечественных и зарубежных исследований в области развития и поддержки одаренных детей дошкольного возраста

The effects of anxiety and situation-specific context on perceptual–motor skill: a multi-level investigation

We examined the effects of anxiety and situation- specific contextual information on attentional, interpretational, and behavioural processes underpinning perceptual– motor performance as proposed by Nieuwenhuys and Oudejans (2012) using an in situ task. Twelve skilled cricket batsmen played against a skilled spin bowler under conditions manipulated to induce low and high levels of anxiety and the presence of low and high levels of situation-specific context. High anxiety decreased the number of good bat– ball contacts, while high levels of situation-specific context increased the number of times the ball was missed. When under high anxiety, participants employed significantly more fixations of shorter duration to more locations, but the effects of anxiety were restricted to the attentional level only. Situation-specific context affected performance and behavioural measures but not anxiety, cognitive load or perceptual–cognitive processes, suggesting that performance is influenced through different mechanisms from anxiety that are independent of working memory load

TEMPORAL AND SPATIAL OCCLUSION OF ADVANCED VISUAL INFORMATION CONSTRAIN EMERGENT COORDINATION OF ONE-HANDED CATCHING BEHAVIOURS

Introduction Dynamic interceptive actions, like catching, are performed under severe spatial and temporal constraints. Here, behavioral processes underpinning one-handed catching was examined using a novel spatial and temporal occlusion design which enabled precise control of pre-release visual information of an actor and a fully coupled action response. Methods An integrated video and ball projection machine was used to create four temporal occlusion and five spatial occlusion conditions of an actor throwing a ball towards participants. Twelve participants’ hand kinematics and gaze behaviors were recorded while attempting to catch a projected ball synchronized with the video footage. Results Temporal occlusion findings revealed that when footage was occluded at earlier time points, catching performance decreased. Movement onset of the catching hand and initiation of visual ball tracking emerged earlier when footage of the thrower was occluded at a later time point in the throwing action. Spatial occlusion did not affect catching success, although movement onset emerged later when increased visual information of the actor was occluded. Later movement onset was countered by greater maximum velocity of the catching hand. The final stages of action (e.g., grasping action of the hand) remained unchanged across both spatial and temporal conditions suggesting the later phases of the action were organised using ball flight information. Discussion Findings revealed how catching behaviors were continuously (re)organized and adapted as information became available in task performance, first by using kinematic information of a thrower's actions, and then by ball flight information. This highlighted the importance of maintaining information-movement coupling during performance of interceptive actions, with these behavioral adaptations having important implications for research that assesses interceptive skills based solely on pre-ball flight information, as in many current video-based simulation paradigms. Contact [email protected]

Reliability of independent kinetic variables and measures of inter-limb asymmetry associated with bilateral drop-landing performance

The purpose of this investigation was to establish the within-session reliability for peak vertical ground reaction force (vGRF), time to peak vGRF, and loading rate, both unilaterally and bilaterally, during a drop-landing task as well as the reliability of inter-limb asymmetry in peak vGRF. Twenty-two men (age = 22 ± 4 years; height = 180.4 ± 6.1 cm; mass = 77.9 ± 14.0 kg) and 17 women (age = 20.4 ± 3.6 years; height = 164.6 ± 9.4 cm; mass = 60.3 ± 9.8 kg) volunteered for a single testing session. Participants completed three maximum countermovement jumps (CMJ) to establish maximum jump height before performing five bilateral drop-landings from 50%, 100%, and 150% of their maximum CMJ height. The bilateral drop-landing protocol was then repeated after a 10 min recovery. Systematic bias, intraclass correlation coefficient (ICC), coefficient of variation (CV%) and minimal detectable change (MDC) values for each kinetic measurement was calculated for the left and right leg, as well as their average. There was no systematic bias present between trials (P > 0.05). All kinetic measurements showed relative reliability, ranging from large to near perfect (ICC = 0.57–0.95). Absolute reliability ranged considerably depending on the measure and drop-height, with peak vGRF and time to peak GRF showing the greatest reliability at higher drop heights (CV% = 6.6–9.7%). Loading rate for all drop heights demonstrated CV% ranging 13.0–27.6%. Furthermore, MDC values for inter-limb asymmetries in peak vGRF ranged between 14.5–16.2% for all drop heights. Overall, many of the kinetic measurements evaluated were sufficiently reliable to detect typical changes in bilateral drop-landing performance when greater drop heights were used

Differences in Motor Control Strategies of Jumping Tasks, as Revealed by Group and Individual Analysis.

The aim of this study was to investigate the motor control strategies adopted when performing two jumping tasks with different task demands when analysed at an individual and group level. Twenty-two healthy individuals performed two jumping tasks: jumping without the use of an arm swing (CMJnas) and jumping starting in a plantar flexed position with the use of an arm swing (PF). Principal component analysis (PCA) was performed using hip, knee and ankle joint moment data on individual (PCAi) and group data (PCAc). The results demonstrate that a greater number of PCs are required to explain the majority of variance within the dataset in the PF condition at both an individual and group level, compared to CMJnas condition. Although common control strategies were observed between the two jumping conditions, differences in the organisation of the movement (PC loading coefficients) were observed. Results from the group analysis did not completely reflect the individual strategies used to perform each jumping task and highlight the value in performing individual analysis to determine emergent control strategies