ABSTRACTThe aims of this study were to identify profiles of sedentary behaviour (SB) patterns, based on leisure-time self-reported SB modalities (screen, educative, social, and relaxing) and to evaluate changes in these profiles over 2 years among Spanish youth aged 8–18 years. Latent profile analysis (LPA), a data-driven analytic approach, was used to identify groups of boys and girls (n = 1553; 48% girls; mean±SD age: 12.56 ± 2.49 y) with distinct SB profiles using the SB modalities (time/d) as input variables. Latent transition analysis, an extension of LPA that uses longitudinal data, was used to analyse 2-year changes in these profiles. At baseline, four and three SB profiles were found among boys (labelled: screen, educative, social, and relaxing) and girls (labelled: screen/social, educative, and relaxing), respectively. Overall, more girls (range: 48%-67%) had the same profile over time, than boys (40%-52%). Participants with a screen or relaxing SB profile at baseline were more likely to have an educative profile after 2 years. Youth with a social and an educative SB profile at baseline were more likely to transition to profiles characterized by higher screen and social SB, respectively. Using a novel and person-centered approach, this study identified gender-specific SB profiles that were moderately stable over time. 相似文献
The purpose of this study was to analyse the raw lifting speed collected during four different resistance training exercises to assess the optimal sampling frequency. Eight physically active participants performed sets of Squat Jumps, Countermovement Jumps, Squats and Bench Presses at a maximal lifting speed. A linear encoder was used to measure the instantaneous speed at a 200 Hz sampling rate. Subsequently, the power spectrum of the signal was computed by evaluating its Discrete Fourier Transform. The sampling frequency needed to reconstruct the signals with an error of less than 0.1% was f99.9 = 11.615 ± 2.680 Hz for the exercise exhibiting the largest bandwidth, with the absolute highest individual value being 17.467 Hz. There was no difference between sets in any of the exercises. Using the closest integer sampling frequency value (25 Hz) yielded a reconstruction of the signal up to 99.975 ± 0.025% of its total in the worst case. In conclusion, a sampling rate of 25 Hz or above is more than adequate to record raw speed data and compute power during resistance training exercises, even under the most extreme circumstances during explosive exercises. Higher sampling frequencies provide no increase in the recording precision and may instead have adverse effects on the overall data quality. 相似文献
Attaining high speed of the stick head and consequently of the ball is essential for successful performance of the drag flick in field hockey, but the coordination pattern used to maximise stick head speed is unknown. The kinematics of the drag flick was studied in ten elite hockey players who performed twenty shots each towards a target located 1.5 m high. A 150 Hz active marker motion analysis system was used, alongside two force plates to detect foot touchdown. Angular velocity and contribution to stick endpoint speed of upper body joints were analysed. Repeated measures ANOVA was used to compare timing of onset and peak angular velocities between joints. Participants used a kinematic pattern that was close to a proximal-to-distal sequence. Trunk axial rotation and lateral rotation towards the target, right wrist flexion and left wrist extension were the main contributors to stick endpoint speed. Coaches should emphasise trunk rotations and wrist flexion and extension movements for maximising stick head speed. Given the high level of the participants in this study, the coordination of joints motions, as reported here, can serve as a guideline for drag flick training. 相似文献
The purpose of this study was to investigate the effects of interval aerobic training combined with strength exercise in the same training session on body composition, and glycaemic and lipid profile in obese rats. Sixteen lean Zucker rats and sixteen obese Zucker rats were randomly divided into exercise and sedentary subgroups (4 groups, n = 8). Exercise consisted of interval aerobic training combined with strength exercise in the same training session. The animals trained 60 min/day, 5 days/week for 8 weeks. Body composition, lipid and glycaemic profiles and inflammatory markers were assessed.
Results showed that fat mass was reduced in both lean and obese rats following the exercise training (effect size (95% confidence interval (CI)) = 1.8 (0.5–3.0)). Plasma low-density lipoprotein–cholesterol and fasting glucose were lower in the exercise compared to the sedentary groups (d = 2.0 (0.7–3.2) and 1.8 (0.5–3.0), respectively). Plasma insulin was reduced in exercise compared to sedentary groups (d = 2.1 (0.8–3.4)). Some exercise × phenotype interactions showed that the highest decreases in insulin, homeostatic model assessment-insulin resistance, fasting and postprandial glucose were observed in the obese + exercise group (all, P < 0.01). The findings of this study suggest that interval aerobic training combined with strength exercise would improve body composition, and lipid and glycaemic profiles, especially in obese rats. 相似文献
This study examines the representations of nanoscale science and technology in written popular media from 1986 to 1999. Nanoscale science is an emergent field that examines the principles of matter at a molecular level. This article presents the representations through which nanoscale science and technology was initially introduced to the public. Written popular media influences the ways stakeholder groups perceive, support, and fund science and technology. From 1986 to 1999 this field was introduced to the general public through articles in newspapers, magazines, and other general interest publications. During this period, nanoscale science and technology had a fragmented public image as proponents of various representations of the field competed for legitimacy. The study demonstrates that the emergence of nanoscience and technology in the popular media occurred as a competitive and transitional social-rhetorical process in which the new emerged within existing and established understandings of science but was mediated by biographical and other social accounts of the research. 相似文献
Assessing individuals as failures in education and training is rarely something that is done lightly or without misgivings. Related to this, the challenges of setting clear threshold or passing standards, are considerable. Assessors’ affective responses during fail scenarios in professional training were explored during focused interviews with 30 academic and practice staff. The pattern of feelings reported at each stage of the decision‐making process, factors which influence judgements and the reactions of others are described. The strength and spread of feelings stand out as an important sources of evidence. Understanding more about these affective responses may assist assessors as they make critical judgements at the margins of professional competence. 相似文献
In this work, we presented an analysis of the representation of the special relativity theory (SRT) in the most used texts
in high school, Polimodal level and university level in the teaching in the Argentine Republic, from a historic, epistemological
and didactic perspective. The results show that none of the analyzed texts would allow a contextualized approach on such theory. 相似文献
Current printed courses of the Open universiteit (Ou) have been designed according to a variety of course models; for example the ‘learning unit model’ or the ‘textbook‐workbook model’ (van den Boom & Schlusmans 1991). Considering the potential of the ILCE approach (Valcke & Martens, this issue), one can imagine new and innovative course models that build on the interactivity and flexibility possibilities of such an environment An essential feature of the ILCE approach is that developers can consider student differences when designing and producing learning materials.
In this article we will explore the problem of adapting the delivery of learning materials to student characteristics in relation to a course based on ‘cases’ in the law domain. Two different study modes are researched: a study mode that starts with the theory and next moves to practical work with the cases versus a study mode that starts with the practical work and next moves to the theoretical base.
Two studies are presented. Within the exploratory study, the research questions focus on the potential interrelations between student characteristics and the preference/choice for one of the two study modes. From the results can be concluded that almost all students from the Open universiteit prefer a theory‐based study mode, because they have a relatively large amount of experience with this study mode and because they find it a successful study mode.
In the second study, an experimental design is adopted with students studying in one of four different conditions: two study modes of printed learning materials and two study modes of interactive learning materials. In contrast with the exploratory study students clearly indicate a more diverse preference for certain study modes. Students also differ in their preference for the delivery mode. However the more traditional study and delivery mode (theory‐based and printed learning material) remains more popular. Again this might again be due to the greater experience students have with this approach. Only two student characteristics are significantly related to opting for the practice‐based study mode: the experience level with a study mode and one's prior knowledge with the subject matter. Comparable results were detected regarding the preferred delivery mode: students with little prior knowledge more readily prefer a printed book, probably because they have a better overview. 相似文献
A framework for planning enrichment activities within a self‐contained classroom is described through the structure of Core‐Explore‐More. At the Core level, activities systematically introduce students to concepts, generalizations and basic skills related to an important curriculum theme. Explore activities allow follow‐up experiences for those students who have been excited and motivated by what they have done at the core level. More activities require greater commitment and individual student initiative because of their specialization. 相似文献
