排序方式: 共有82条查询结果,搜索用时 15 毫秒
61.
Antony G. Philippe Fabio Borrani Guillaume Py Robin Candau 《Journal of sports sciences》2019,37(3):254-261
System theory is classically applied to describe and to predict the effects of training load on performance. The classic models are structured by impulse-type transfer functions, nevertheless, most biological adaptations display exponential growth kinetics. The aim of this study was to propose an extension of the model structure taking into account the exponential nature of skeletal muscle adaptations by using a genetic algorithm. Thus, the conventional impulse-type model was applied in 15 resistance trained rodents and compared with exponential growth-type models. Even if we obtained a significant correlation between actual and modelled performances for all the models, our data indicated that an exponential model is associated with more suitable parameters values, especially the time constants that correspond to the positive response to training. Moreover, positive adaptations predicted with an exponential component showed a strong correlation with the main structural adaptations examined in skeletal muscles, i.e. hypertrophy (R2 = 0.87, 0.96 and 0.99, for type 1, 2A and 2X cross-sectional area fibers, respectively) and changes in fiber-type composition (R2 = 0.81 and 0.79, for type 1 and 2A fibers, respectively). Thus, an exponential model succeeds to describe both performance variations with relevant time constants and physiological adaptations that take place during resistance training. 相似文献
62.
Guillaume Escalié Nicolas Recoules Sébastien Chaliès Pascal Legrain 《Sport, Education and Society》2019,24(4):390-403
In the French education system, the current curriculum for students from the primary to the end of secondary school is structured around the notion of key competence. A competence can be defined as an integrated and stable network of knowledge and know-how, with normative behaviors, procedures and types of reasoning. However, without a theoretical conceptualization of building and mobilization processes, the components of a competence are considered as isolated and not interconnected. In the health and physical education (HPE) setting, too few empirical studies have analyzed how teachers would contribute to the development of student’s competence. The aim of this forward-looking article grounded on an experiential and cultural framework consists in clarifying and illustrating a conceptualization of the dynamics of development of competences among students considering the teacher activity. This theoretical framework seems to offer heuristic possibilities for the examination of teaching and learning practices which contribute to the development of the key competences, particularly when a competence is read as an experience that integrates multiple dimensions. Based on audio-video recording of PE lessons and self-confrontation interviews with the teacher and a student, the results of the present study strengthen the criticism of the definition of competence emphasizing the relevance to adopt a holistic approach corresponding to the articulation of intertwined resources (i.e. motor, methodological and social) students allocate to act in PE groups. Furthermore, the results show that the competence building depends on various roles students have the opportunity to play in PE (i.e. observer, tutor). Finally, our results underline the importance of identifying the specific characteristics of the teacher activity designed to structure the learning environment to train students to acquire new competences transferable in society. 相似文献
63.
64.
A procedure to enhance the faded colours of museums artefacts is presented. The method is based on adjusting the spectral profile of the light while maintaining a given white colour of the illumination. The procedure is tested using colour LED clusters and a series of damaged samples and their good condition counterparts. The intensity of the three components of four feasible LED clusters is computed in order to produce white illumination metameric to a white LED light source taken as a reference. Colorimetric calculations are performed to model the colour changes undergone by target colour samples using illumination based on colour LED association with respect to the white LED reference. The model is based on CIELAB specification and allows to optimize the choice of three-colour LED associations that modify the hue and the saturation of a few target colour areas of illuminated samples while other areas are left moderately desaturated. Modelling and experimental visual validation were practically obtained by adjusting the intensity of five calibrated colour LEDs, blue, cyan, green, amber and red, accommodated in a light booth. A visual validation was conducted asking 20 observers to rate the colourfulness appearance of aged inkjet prints under every LED cluster with respect to the colourfulness of their original counterparts under the reference white LED source. The visual assessments agreed with the colorimetric predictions. Finally, a demonstration is shown of the feasibility of the method by simulating the rejuvenated appearance of a natural history specimen of which the museum possesses two differently aged items. 相似文献
65.
Arash Khassetarash Gianluca Vernillo Renata L.Krüger W.Brent Edwards Guillaume Y.Millet 《运动与健康科学(英文)》2022,11(3):319-329
Purpose:This study used downhill running as a model to investigate the repeated bout effect(RBE) on neuromuscular performance,running biomechanics,and metabolic cost of running.Methods:Ten healthy recreational male runners performed two 30-min bouts of downhill running(DR1 and DR2) at a-20% slope and 2.8 m/s3 weeks apart.Neuromuscular fatigue,level running biomechanics during slow and fast running,and running economy parameters were recorded immediately before and after the downhill bouts,and at... 相似文献
66.
Tobias Wiesenthal Guillaume LeducKarel Haegeman Hans-Günther Schwarz 《Research Policy》2012,41(1):116-131
This paper discusses a bottom-up approach to estimate the level of R&D investment by technology in areas where data are scarce. It develops a four-step methodology for the estimation of corporate R&D investments at technology level. This approach can overcome gaps in existing data by combining publicly available information in a novel way, even though it introduces some uncertainty. This is illustrated for a set of low-carbon energy technologies that were identified as key for meeting Europe's long-term energy and climate objectives by the European Strategic Energy Technology Plan. The paper finds that the aggregated R&D investments dedicated to these technologies amounted to €3.3 billion in the EU in 2007, including public funding from European Union Member States and at EU-level, and industrial research activities from companies with headquarters registered in the EU. The results allow conclusions on the European energy research policy to be drawn, such as the dominance of industrial funds, and have provided significant input to the European policy making in this field. The paper ends with suggestions on how to further enhance the accuracy of the approach and how to widen its application to other sectors. 相似文献
67.
Vercruyssen F Boitel G Alberty M Nesi X Bourdon L Brisswalter J 《Journal of sports sciences》2012,30(10):1055-1061
The aim of this study was to examine the effect of kick frequency on metabolic efficiency and performance in elite monofin-swimmers at the surface. Seven participants of international calibre were requested to perform three separate time limit exercises conducted at an intensity corresponding to 97.5% of the velocity at the maximal oxygen uptake. The first Time Limit exercise was systematically conducted at a freely chosen kick frequency (FCK(F)) and the other Time Limit exercises were performed in random order at FCK(F)-10% and FCK(F) + 10%. The slow component of oxygen uptake (VO2sc) was identified independently of the Time Limit exercise (ranging from 180 to 243 ml · min(-1), P < 0.05). No significant change in energy cost of aquatic locomotion (ranging from 565 to (596 J · m(-1)) and [VO2sc) responses was observed between the three Time Limit exercises. An increase or decrease of 10% of the FCK(F) was associated with a significant reduction in Time Limit of -47.3% and -49.1%, respectively (P < 0.05). The analysis of the Time Limit exercise indicates that the selection of kick frequency other than FCK(F) is detrimental to overall monofin-swimming performance. Furthermore, the study results showed that the indicators of metabolic efficiency such as energy cost or [VO2sc) do not determine the performance response in elite monofin-swimmers at a severe intensity. 相似文献
68.
69.
Yohan Saby Yann Pupier Emma Guillet-Descas Michel Nicolas Guillaume Martinent 《Journal of sports sciences》2020,38(11-12):1368-1379
ABSTRACT Grounded in Lazarus’s (1999) cognitive motivational relational theory of emotions, this study aimed to explore longitudinal relationships between appraisals, everyday emotions related to the competitive environment and emotional regulation strategies during a competitive season. Forty adolescent soccer players (Mage = 15.8) involved in an intensive training centre from a professional club voluntarily participated to the study. A series of hierarchical linear modelling analyses were conducted upon the 9 measurement times to: (a) examine the relationships between appraisals (threat, challenge, loss), pleasant (happiness, excitement) and unpleasant (anxiety, dejection, anger) emotions, and emotional regulation strategies (adaptive and less adaptive); and (b) ascertain whether the relationships between appraisals and emotions were mediated by emotion regulation strategies. The results of the random coefficient regression models showed: (a) positive relationships between challenge appraisal, adaptive emotion regulation, and pleasant emotions as well as between threat and loss appraisals, less adaptive emotion regulation and unpleasant emotions; and (b) mediating effects of emotional regulation strategies in the appraisals – emotions relationships. As a whole, this study furthered knowledge base about the competitive environment in showing that appraisals, emotion regulation and emotions are intertwined psychological constructs in a dynamic relationship allowing athletes to continuously adjust to their constantly changing everyday demands. 相似文献
70.
Guillaume Millet Stéphane Perrey Caroline Divert Matthieu Foissac 《Sports Engineering》2006,9(4):209-220
The purpose of this review is to discuss how an athlete’s fatigue can be limited by using recent innovations in sports engineering.
The review focuses on human locomotion, i.e. mainly fatigue during endurance sports. First, through a general definition and
illustrations of means of locomotion such as running, cycling, walking/hiking or speed skating, several aspects of fatigue
reduction will be presented. With regards to the mechanical stress, it has been shown that (i) contrary to ‘invitro’ experiments and, in comparison with hard shoes, soft shoes do not appear to reduce impact forces during running and (ii)
too much cushioning can have side effects in terms of energy cost and thus in terms of fatigue in running and mountain biking.
On the contrary, the equipment weight-that also depends on the weight repartition may have dramatic effects in terms of fatigue.
Any equipment allowing better mechanical efficiency (e.g. chainrings, klapskate) or work distribution (e.g. walking with poles)
can potentially reduce an athlete’s fatigue under similar conditions without this equipment. However, among elite athletes,
the use of technical innovation does not seem to affect fatigueper se but provides performance improvement with similar fatigue occurrence. It appears that fatigue-related improvements caused
by technical innovations only occur among sportsmen exercising for leisure. In the second part of this review, recent textile
innovations aimed at decreasing fatigue by the use of elastic compression stockings or at regulating temperature will be discussed.
Finally, two methods designed to improve recovery after training or competition (elastic compression and electromyostimulation)
will be discussed. Both these techniques are widely used by elite athletes despite relatively poor scientific evidence of
their efficiency, with the exception of recovery after eccentric exercise. 相似文献