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51.
Guillaume Martinent Valérian Cece Marije Titia Elferink-Gemser Irene Renate Faber Jean-Claude Decret 《Journal of sports sciences》2018,36(23):2724-2731
ABSTRACTThis study examined the prognostic relevance of self-determined motivation, coping, burnout, perceived stress and recovery experienced by 159 youth table-tennis players involved in intensive training centers with regard to their participation and success six years later. Results of ANCOVAs showed that players who still practiced at time 2 (T2; six years later; n = 130) reported lower time 1 (T1; while they were involved in intensive training centers) amotivation (large effect), disengagement-oriented coping, sport devaluation and reduced accomplishment (moderate effects) than their counterparts who dropped out at T2 (n = 29). Results of ANCOVAs also showed that international (n = 18) and/or national players (n = 86) at T2 reported significantly lower T1 amotivation (large effect), disengagement-oriented coping and sport devaluation (moderate effects) in comparison to regional (n = 26) players at T2. Finally results of correlational analyses showed that T2 performance and/or six-year performance progress were significantly and weakly correlated with introjected and external regulations, perceived stress and perceived recovery, and significantly and moderately correlated with amotivation, disengagement-oriented coping, sport devaluation, and reduced accomplishment. Overall, this study provided insights into the role played by self-determined motivation, coping, burnout, perceived stress and recovery in the table-tennis players’ dropout and performance level six years later. 相似文献
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C. S. Khachikian D. W. Guillaume T. K. Pham 《European Journal of Engineering Education》2011,36(6):595-605
Students were surveyed and asked to self-evaluate their performance and time-on-task in six engineering courses (eight sections). Surveys were conducted four times over the course of a 10-week quarter. Students with the highest grade point averages (GPAs) (2.88 mean; 4.00 mode) indicated ‘no change’ while students with lower GPAs (2.67 mean; 1.83 mode) indicated a ‘negative change’ in grade expectations by the end of the quarter, indicating that better performing students are better self-evaluators. Students reduced time-on-task 2–4 hours/week, especially early in the quarter. Students who changed their time-on-task during each survey had a GPA mode of 4.00, indicating that ‘master’ students readily adapt to course demands. This study shows that most students over-predict their grades and their level of commitment to a course and lose confidence in their abilities as the term progresses. It is suggested that instructors obtain student grade predictions and use them to provide timely and appropriate feedback. 相似文献
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Michel Nicolas Guillaume Martinent Guillaume Millet Virginie Bagneux Marvin Gaudino 《Journal of sports sciences》2019,37(16):1831-1839
This research examined the time courses of emotions in sport settings (anxiety, dejection, anger, happiness, excitement) experienced by mountain ultra-marathon (MUM) runners within the month following a demanding MUM race and the role of emotional intelligence (EI) in these time courses. A six-wave one-month longitudinal design was used with one measurement point within two days before the race to measure EI and five time points within the month following the race to assess emotions experienced among a sample of 29 runners. Results of multilevel growth curve analyses showed significant linear decreases of dejection and anxiety and a significant linear increase of anger. EI was related to the intercept (level at the end of the MUM race) of happiness, excitement and dejection. Moreover the interaction of EI with time was associated with happiness, excitement and anger. This means that high and low emotional intelligent runners exhibited distinct trajectories of emotional intelligence within the month following the MUM race. Indeed, trait-EI appeared to have a protective role against stress process leading to emotional adjustment within the recovery period following an ultra-endurance event. As such, consultants and coaches could conduct specific program over the sport season designed to enhance trait-EI of MUM runners. 相似文献
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Delphine Chadefaux Guillaume Rao Jean-Loïc Le Carrou Eric Berton Laurent Vigouroux 《Journal of sports sciences》2017,35(12):1155-1164
The aim of this article is to characterise the extent to which the dynamic behaviour of a tennis racket is dependent on its mechanical characteristics and the modulation of the player’s grip force. This problem is addressed through steps involving both experiment and modelling. The first step was a free boundary condition modal analysis on five commercial rackets. Operational modal analyses were carried out under “slight”, “medium” and “strong” grip force conditions. Modal frequencies and damping factors were then obtained using a high-resolution method. Results indicated that the dynamic behaviour of a racket is not only determined by its mechanical characteristics, but is also highly dependent on the player’s grip force. Depending on the grip force intensity, the first two bending modes and the first torsional mode frequencies respectively decreased and increased while damping factors increased. The second step considered the design of a phenomenological hand-gripped racket model. This model is fruitful in that it easily predicts the potential variations in a racket’s dynamic behaviour according to the player’s grip force. These results provide a new perspective on the player/racket interaction optimisation by revealing how grip force can drive racket dynamic behaviour, and hence underlining the necessity of taking the player into account in the racket design process. 相似文献
55.
In recent years, policy approaches that build upon the notion of innovation systems have enjoyed increasing attention in science, technology and innovation policy. But while the usefulness of systemic thinking in policy-making has been demonstrated in a large number of empirical settings, we still lack a detailed understanding of the dynamics at play when policy makers address systemic problems. In this paper, we show how complex interdependencies and the uncertain nature of technological change shape the process of targeted policy interventions in socio-technical systems. Toward this end we analyzed the evolution of the German feed-in tariff (FIT) system for solar photovoltaic power, a highly effective and widely copied policy instrument targeted at fostering the diffusion and development of renewable energy technologies. We find that the policy has been subject to a considerable amount of changes, many of which are the result of policy makers addressing specific system issues and bottlenecks. Interestingly, however, often these issues themselves were driven by unforeseen technological developments induced by previous policy interventions. We argue that the pattern of policy serving as both a solution to and a driver of technological bottlenecks shows strong similarities with what Rosenberg (1969) called ‘compulsive sequences’ in the development of technical systems. By shedding more light on how the characteristics of socio-technical systems affect policy interventions, our framework represents a first step toward more closely integrating the literature on innovation systems with the work on policy learning. 相似文献
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Execution time, kinetics, and kinematics of the mae-geri kick: comparison of national and international standard karate athletes 总被引：1，自引：1，他引：0
Little is known of the performance characteristics of the shotokan karate mae-geri kick. The aim of this study was to compare the execution time, the lower limb kinetics and kinematics, and their respective repeatability in the mae-geri kick of karate athletes of two different standards. Seventeen adult black belt karate competitors (9 national and 8 international athletes) performed six kicks with their dominant lower limb on a striking surface, combining maximum force impact and velocity. Execution time of movement and lower limb kinematics were recorded with a high-speed camera. Maximum force at impact and the forces exerted on the ground were measured using three force plates. The duration of the kick was significantly shorter for international than for national standard athletes. However, no significant difference in the maximum impact force of the kick was observed between the two groups. In addition, significant kinematic differences were observed between the groups, with two angles of motion and one velocity peak occurring sooner in the kick movement for the international athletes, specifically for the knee joint. International athletes also performed the kick with a significantly higher repeatability for duration and kinematics, specifically during the pre-loading phase that precedes the attack phase. We conclude that the duration of the kick and repeatability of lower limb kinematics could be useful in selecting top-level karate athletes and monitoring their training status. 相似文献
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The aims of this study were to (1) investigate the influence of general anthropometric variables, handball-specific anthropometric variables, and upper-limb power and strength on ball-throwing velocity in a standing position (ν(ball)), and (2) predict this velocity using multiple regression methods. Forty-two skilled male handball players (age 21.0?±?3.0 years; height?=?1.81?±?0.07?m; body mass?=?78.3?±?11.3?kg) participated in the study. We measured general anthropometric variables (height, body mass, lean mass, body mass index) and handball-specific anthropometric parameters (hand size, arm span). Upper-limb dynamic strength was assessed using a medicine ball (2?kg) throwing test, and power using a one-repetition maximum bench-press test. All the variables studied were correlated with ball velocity. Medicine ball throwing performance was the best predictor (r?=?0.80). General anthropometric variables were better predictors (r?=?0.55-0.70) than handball-specific anthropometric variables (r?=?0.35-0.51). The best multiple regression model accounted for 74% of the total variance and included body mass, medicine ball throwing performance, and power output in the 20-kg bench press. The equation formulated could help trainers, athletes, and professionals detect future talent and test athletes' current fitness. 相似文献
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Felipe Mattioni Maturana Arthur Peyrard John Temesi Guillaume Y. Millet 《Journal of sports sciences》2018,36(10):1095-1102
This study compared the responses of two priming exercises of similar fatigue on the adjustment of the oxygen uptake time constant (τV?O2) in cycling. Ten healthy young adults (25 ± 3 yr) performed: three step transitions from a 20-W baseline to the power output (PO) below the gas exchange threshold (MOD, MODPRE); a 3-min bout (P3MIN) at 90% of peak PO (POpeak), followed by MOD (MOD3MIN); and a 6-min bout (P6MIN) at 80% of POpeak, followed by MOD (MOD6MIN). The O2 supply-to-O2 demand ([HHb]/V?O2) ratio was calculated for MODPRE, MOD3MIN, and MOD6MIN. Neuromuscular fatigue was measured isometrically pre- and post-priming exercise. Reductions in maximal voluntary contraction (?29 ± 6 vs ?34 ± 7%) and high-frequency doublet amplitude (?48 ± 13 vs ?43 ± 11%) were not significantly different between P3MIN vs P6MIN, suggesting similar fatigue. τV?O2 for MOD3MIN and MOD6MIN were similar, being ~25% smaller than MODPRE. The [HHb]/V?O2 ratio was significantly greater in MODPRE (1.13 ± 0.12) compared to MOD3MIN (1.02 ± 0.04) and MOD6MIN (1.02 ± 0.04). This study showed that priming exercise of shorter duration and higher intensity, was sufficient to accelerate V?O2 kinetics similarly to that observed subsequent to P6MIN when the muscle fatigue was similar. 相似文献