Effects of manipulating relative and absolute motion information during observational learning of an aiming task

In the visual perception perspective of observational learning, the manipulation of relative and absolute motion information in visual demonstrations optimally directs learners’ search towards appropriate task solutions. We assessed the effect of emphasizing transformational information and removal of structural information using point-light kinematic displays in approximating the model’s relative motion patterns. Participants viewed computer-simulated point-light demonstrations or normal video demonstrations before and intermittently throughout 100 acquisition trials with knowledge of results on an underarm modified-dart aiming task. On the next day, all participants performed 20 retention trials without demonstrations. The kinematics of spatial and temporal coordination and control variables were examined relative to the model’s action, as well as performance scores. The results indicated that approximation of the model’s spatial and temporal coordination and control patterns was achieved after observation of either type of demonstrations. No differences were found in movement outcomes. In a second experiment, the effects of manipulating absolute motion information by slowmotion demonstrations were examined relative to real-time demonstrations. Real-time demonstrations led to a closer approximation to the model’s spatial and temporal coordination patterns and better outcome scores, contradicting predictions that slow-motion displays convey intact relative motion information. We speculate that the effect of visual demonstration speed on action perception and reproduction is a function of task constraints ‐ that is, novelty or familiarity of relative motion of demonstrated activities.     

The continuous nature of timing reprogramming in an interceptive task

The time course of movement timing reprogramming was examined in a task requiring temporal coincidence of the conclusion of a forehand drive with the arrival of a moving luminous target at the end of an electronic trackway. The moving target departed from one end of the trackway at a constant velocity of 2?m ^. s^?1, and for a part of the trials its velocity was increased to 3?m ^. s^?1. Target velocity was modified at different moments during stimulus displacement, producing times-to-arrival after velocity increment (TAVIs) from 100 to 600?ms. The effect of specific practice on movement reprogramming was also examined. The results showed early adjustments to the action (TAVIs = 100?–?200?ms) that seemed to be stereotyped, while feedback-based corrections were implemented only at TAVIs of 300?ms or longer. Temporal accuracy was progressively increased as longer TAVIs were provided up to 600?ms. Skill training led to an overall increment of temporal accuracy, but no effect of specific practice was found. The results indicate that timing reprogramming in interceptive actions is a continuous process limited mainly by intrinsic factors: latency to initiate more effective adjustments to the action, and rate-of-movement timing reprogramming.     

The effects of task constraints on visual search behavior and decision-making skill in youth soccer players

We examined differences in visual search behaviors and decision-making skill across different microstates of offensive play in soccer using youth participants (13.0-15.8 years) varying in skill and experience. We used realistic film simulations of offensive play, movement-based response measures, and an eye movement registration technique. Playing experience, skill level, and the unique constraints of the task, expressed by the number of players and relative proportion of offensive and defensive players, determined both the observed search behavior and processing requirements imposed on players in dynamic offensive team simulations. Significant differences in performance were observed between players and nonplayers and across three groups of soccer players who differed in skill level. Implications for talent identification and development are considered.     

Futsal task constraints promote transfer of passing skill to soccer task constraints

This study investigated how learning a passing skill with futsal or soccer task constraints influenced transfer to a new task. Futsal (n?=?24, 13.6?±?1.2 years old, 7.0?±?1.6 years of experience) and soccer (n?=?24, 13.6?±?1.2 years old, 6.8?±?1.2 years of experience) players performed two 5v5?+?goalkeeper modified games – a futsal-like task (small playing area with the futsal ball) and soccer-like task (large playing area with the soccer ball). Participants’ passing accuracy and their orientation of attention were assessed during the two tasks. The futsal group improved their passing accuracy (ES?=?0.75?±?0.61) from the futsal-like to the soccer-like task, and they were more accurate than soccer players (ES?=?2.98?±?2.96). Conversely, the soccer group’s passing accuracy remained stable across the two tasks (ES?=?0.10?±?0.52) and it was similar to the futsal group in the futsal-like task (ES?=?0.58?±?1.93). This indicates a higher magnitude of transfer (and adaptability) from performing passes in a small playing area with short time to act – futsal task constraints – to a larger playing area with longer time – soccer task constraints – than vice-versa. Furthermore, the futsal group showed a higher adaptation of attention orientation to the affordances that emerged with the soccer task constraints, which is suggested to be one of the main mechanisms promoting skill transfer. These results encourage soccer practitioners to introduce futsal task constraints to fast-track players’ ability to functionally adapt perception–action coupling.     

Charity sport event participants and fundraising: An examination of constraints and negotiation strategies

Charity sport events provide participants with a meaningful event experience, and the opportunity to support a charitable cause is a critical component of this experience. This opportunity often involves fundraising, either as a requirement of event participation or as an option to supplement registration. However, fundraising as part of charity sport event participation is a difficult task. In the current research, the authors examine the challenges faced by charity sport event participants in soliciting donations, and the effort made to overcome these challenges. Constraint negotiation served as a theoretical framework to guide this examination. Semi-structured interviews (N = 27) were conducted with Triathlon Pink participants to discuss their fundraising process and their attitudes towards fundraising. Four constraints were revealed: lack of receptivity among potential donors, perceived lack of money from potential donors, discomfort in asking, and lack of time. These constraints were negotiated through three strategies: narrative, prizes and incentives, and emphasising that any bit helps. Based upon the themes uncovered, charity sport event managers can implement increased education of fundraisers and point of sale donations within the registration process.     

The association between fundamental athletic movements and physical fitness in elite junior Australian footballers

This study investigated the associations between fundamental athletic movement and physical fitness in junior Australian football (AF). Forty-four under 18 players performed a fundamental athletic movement assessment consisting of an overhead squat, double lunge, single leg Romanian deadlift and a push up. Movements were scored on three assessment criterions using a three-point scale. Additionally, participants performed five physical fitness tests commonly used for talent identification in AF. A Spearman’s nonparametric correlation matrix was built, with correlation coefficients being visualised using a circularly rendered correlogram. Score on the overhead squat was moderately positively associated with dynamic vertical jump height on left (r_s = 0.40; P ≤ 0.05) and right (r_s = 0.30; P ≤ 0.05) leg take-off, stationary vertical jump (r_s = 0.32; P ≤ 0.05) and negatively associated with 20-m sprint time (r_s = ?0.35; P ≤ 0.05). Score on the double lunge (left/right side) was moderately positively associated with the same physical fitness tests as well as score on the multistage fitness test. Results suggest that improvements in physical fitness qualities may occur through concurrent increases in fundamental athletic movement skill, namely the overhead squat and double lunge movements. These findings may assist with the identification and development of talent.     

Effects of different instructional constraints on task performance and emergence of coordination in children

Abstract

The objectives of this study were to determine the impact of different instructional constraints on standing board jump (sbj) performance in children and understand the underlying changes in emergent movement patterns. Two groups of novice participants were provided with either externally or internally focused attentional instructions during an intervention phase. Pre- and post-test sessions were undertaken to determine changes to performance and movement patterns. Thirty-six primary fourth-grade male students were recruited for this study and randomly assigned to either an external, internal focus or control group. Different instructional constraints with either an external focus (image of the achievement) or an internal focus (image of the act) were provided to the participants. Performance scores (jump distances), and data from key kinematic (joint range of motion, ROM) and kinetic variables (jump impulses) were collected. Instructional constraints with an emphasis on an external focus of attention were generally more effective in assisting learners to improve jump distances. Intra-individual analyses highlighted how enhanced jump distances for successful participants may be concomitant with specific changes to kinematic and kinetic variables. Larger joint ROM and adjustment to a comparatively larger horizontal impulse to a vertical impulse were observed for more successful participants at post-test performance. From a constraints-led perspective, the inclusion of instructional constraints encouraging self-adjustments in the control of movements (i.e., image of achievement) had a beneficial effect on individuals performing the standing broad jump task. However, the advantage of using an external focus of attentional instructions could be task- and individual-specific.     

Similarities and differences in constraints and constraint negotiation among Japanese sport tourists: a case of masters games participants*

ABSTRACT

The purposes of this study were to examine (a) similarities and differences in constraints to and constraint negotiation for masters games (MG) participation, and (b) the relationships among constraints, constraint negotiation, and intention to participate in the World Masters Games 2021 Kansai, across international sport tourists, domestic sport tourists, and sport excursionists. An online survey was conducted with 449 Japanese people who participated in MGs within the last three years. Our results indicated that international sport tourists experienced higher levels of psychological, physiological, interpersonal, financial, tourism, commitment, MG-specific constraints than domestic sport tourists and sport excursionists, although physiological constraints did not differ between international and domestic sport tourists. Conversely, international and domestic sport tourists utilized tourism and MG-self-adaptation negotiation strategies more than sport excursionists. Lastly, constraints to and constraint negotiation for the past MG were not related to the intention of participation in the World Masters Games 2021 Kansai across the three groups. These results suggest that this typology of sport tourists – international, domestic, and excursionist – is an effective framework to understand constraints and negotiation as well as other behaviors and experiences of Japanese sport tourists.     

Effect of speed on local dynamic stability of locomotion under different task constraints in running

Abstract

A number of studies have investigated effects of speed on local dynamic stability of walking, although this relationship has been rarely investigated under changing task constraints, such as during forward and backward running. To rectify this gap in the literature, the aim of this study was to investigate the effect of running speed on local dynamic stability of forward and backward running on a treadmill. Fifteen healthy male participants took part in this study. Participants ran in forward and backward directions at speeds of 80%, 100% and 120% of their preferred running speed. The three-dimensional motion of a C7 marker was recorded using a motion capture system. Local dynamic stability of the marker was quantified using short- and long-term largest finite-time Lyapunov exponents (LyE). Results showed that short-term largest finite-time LyE values increased with participant speed meaning that local dynamic stability decreased with increasing speed. Long-term largest finite-time LyEs, however, remained unaffected as speed increased. Results of this study indicated that, as in walking, slow running is more stable than fast running. These findings improve understanding of how stability is regulated when constraints on the speed of movements is altered. Implications for the design of rehabilitation or sport practice programmes suggest how task constraints could be manipulated to facilitate adaptations in locomotion stability during athletic training.     

我国冰壶运动发展优势及制约因素分析

文章通过文献资料法、调查法、数理统计法、逻辑分析法对我国冰壶运动发展进行研究,结果发现：冰壶运动的项目技术特点、对年龄的要求、场地及器材要求等是其在我国迅速发展的主要优势;同时,人才培养方式、项目的宣传力度不够、场地数量与质量不足、教练员水平不够是制约其发展的主要因素。     

How do technique and coordination change during learning of a whole-body task: Application to the upstart in gymnastics

ABSTRACT

When learning swinging skills on a bar there has been conflicting advice in the research literature regarding whether to coach the “gold standard” technique to novices. The present study aimed to determine how technique (joint angle time histories) and (inter-limb) coordination changed as novice gymnasts learned a fundamental gymnastics skill (the upstart). It was hypothesised that both technique and coordination would become more like an expert as learning progressed. Eight novice gymnasts, unable to perform an upstart, underwent four months of training, with the number of successful upstarts out of 10 recorded at the start and then every month subsequently. In the first and last sessions motion capture was used to determine joint kinematics. Root mean squared differences for the joint angle time histories and continuous relative phase at the shoulder and hip were calculated between the novices and an expert gymnast. As training progressed technique and coordination became more like the expert gymnast. The more successful novices were better able to time their actions within the swing than the less successful novices. Gymnastics coaches teach towards a “gold standard” technique since being successful at the skill is not the only goal, as considerations for future skill development are made.     

关于足球赛中“抢逼围”作用的探索

通过对上海巾花足球队1994、1995两年甲A联赛中抢断球的统计分析,阐述“抢逼围”在当今我国足球比赛中的作用,扼要介绍巾花队在训练中贯彻这一指导思想的原则措施。     

The effects of control-display gain on performance of race car drivers in an isometric braking task

Abstract

To minimise lap times during car racing, it is important to build up brake forces rapidly and maintain precise control. We examined the effect of the amplification factor (gain) between brake pedal force and a visually represented output value on a driver's ability to track a target value. The test setup was a formula racing car cockpit fitted with an isometric brake pedal. Thirteen racing drivers performed tracking tasks with four control-display gains and two target functions: a step function (35 trials per gain) and a multisine function (15 trials per gain). The control-display gain had only minor effects on root mean-squared error between output value and target value, but it had large effects on build-up speed, overshoot, within-participants variability, and self-reported physical load. The results confirm the hypothesis that choosing an optimum gain involves balancing stability against physical effort.     

The effects of required amplitude and practice on frequency stability and efficiency in a cyclical task

From an ecological point of view, motor learning emerges from the interplay of constraints on action, which shape behaviour towards the optimal solution, and practice, conceived as an active exploration of the work-space, to search this optimal solution. In the experiment reported here, we studied this interplay for a cyclical task performed on a ski-simulator. Our aim was to assess the respective effects of amplitude and practice on frequency variability and efficiency. On the basis of previous empirical findings, amplitude was expected, beyond a critical value, to constrain and stabilize the frequency of the movement. Three groups of participants practised during four sessions at three different amplitudes (15, 22.5 and 30 cm). The results showed that participants moving at large amplitude displayed more stable and more consistent frequencies. Nevertheless, there was no interaction effect between target amplitude and practice. On the other hand, movement economy and harmonicity increased with practice, but were not affected by amplitude. Finally, the results of transfer tests showed that the effects of large amplitude on frequency variability were not resistant to a subsequent decrease in target amplitude. These results suggest that constraints and practice act independently on motor behaviour, and that a high constraint could be detrimental to the development of effective search strategies.     

From the field of play to the laboratory: Recreating the demands of competition with augmented reality simulated sport

ABSTRACT

Biomechanical analysis has typically been confined to a laboratory setting. While attempts have been made to take laboratory testing into the field, this study was designed to assess whether augmented reality (AR) could be used to bring the field into the laboratory. This study aimed to measure knee load in volleyball players through a jump task incorporating AR while maintaining the perception-action couplings by replicating the visual features of a volleyball court. Twelve male volleyball athletes completed four tasks: drop landing, hop jump, spike jump, and spike jump while wearing AR smart glasses. Biomechanical variables included patellar tendon force, knee moment and kinematics of the ankle, knee, hip, pelvis and thorax. The drop landing showed differences in patellar tendon force and knee moment when compared to the other conditions. The hop jump did not present differences in kinetics when compared to the spike conditions, instead of displaying the greatest kinematic differences. As a measure of patellar tendon loading the AR condition showed a close approximation to the spike jump, with no differences present when comparing landing forces and mechanics. Thus, AR may be used in a clinical assessment to better replicate information from the competitive environment.     

我国体育用品业自主创新能力障碍因素研究

我国体育用品业自主创新能力的不足,已严重影响了我国体育经济的持续、健康发展。本文主要对我国体育用品业自主创新能力进行研究,对影响我国体育用品自主创新能力的障碍因素进行系统分析,找出其成因,进而提出提高我国体育用品业自主创新能力的发展对策,提出一些对我国体育用品业自主创新有益的建议,以期给国内体育用品业以借鉴,促进我国体育用品业又好又快发展。     

我国高校体育产业化的制约因素与发展对策研究

采用文献资料和逻辑分析等方法,运用经济学、管理学、社会学和体育学等相关理论,对我国高校体育产业化的制约因素和发展对策进行研究。我国高校体育产业虽说拥有稳定的消费群体、充分的闲暇时间、优越的人力资源和丰富的物质设施等优势,但产业化过程中存在思想观念滞后、政策法规的支持力度不够、产权关系不明晰且经营范围偏小、经营方式单一且经营资金不足、缺乏经营人才而管理水平偏低等制约因素;进一步解放思想和转变观念、利用自身的资源优势开拓市场、完善政策法规和推进社会化改革、加强对体育产业应用型人才的培养等方面提出相应的发展对策。     

多媒体体育教学应用与展望

介绍多媒体教学的应用条件、应用类型、应用特点以及应用前景,分析了多媒体体育教学的应用特点,提出了多媒体在体育教学中应用的研究思路。     

体育科研常用生化分析仪质量控制

本文论述了体育科研常用生化分析仪质量控制的方法。多年工作实践表明，本文提出的方法可保证体育科研常用生化分析仪分析结果的重复性和准确性。