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211.
The aim of this study was to examine acute physiological responses and time-motion characteristics associated with three different small-sided soccer game formats in youth players. Sixteen male soccer players aged 16.3+/-0.6 years (mean+/-s) completed three variations of a small-sided game (i.e. 2 vs. 2, 4 vs. 4, and 6 vs. 6 players) in which heart rate, rating of perceived exertion (RPE), blood lactate concentration, and time-motion characteristics were recorded. The pitch size was altered to keep the relative pitch area per player consistent for each game format. The 2 vs. 2 games exhibited greater blood lactate, heart rate, and RPE responses compared with 4 vs. 4 and 6 vs. 6 games (P<0.05). The players travelled less (P<0.05) distance at speeds of 0-7 km.h(-1) in the 4 vs. 4 compared with the 2 vs. 2 games (1128+/-10 m and 1176+/-8 m, respectively). Average maximal sprint distances above 18 km.h(-1) were lower (P<0.05) in 2 vs. 2 than in 4 vs. 4 and 6 vs. 6 games (11.5+/-3.9 m, 15.3+/-5.5 m, and 19.4+/-5.9 m, respectively), and in 4 vs. 4 compared with 6 vs. 6 games. The results show that as small-sided game formats decrease in size and relative pitch area remains constant, overall physiological and perceptual workload increases. 相似文献
212.
Maximal work production following two levels of artificially induced metabolic alkalosis 总被引:2,自引:1,他引:1
D C McKenzie K D Coutts D R Stirling H H Hoeben G Kuzara 《Journal of sports sciences》1986,4(1):35-38
In order to determine the influence of two artificially induced alkalotic states on the ability to perform maximal exercise, six male subjects (mean age, 22.0 years; mean height, 176.8 cm; mean weight, 69.1 kg; mean VO2 max, 3.83 l min-1) were studied during three experimental trials. The subjects performed six 60-s cycling bouts, at a work rate corresponding to 125% VO2 max, with 60 s recovery between work bouts; these regimens were performed 1 h after the ingestion of a solution containing either; I, placebo; II, NaHCO3 in a dosage of 0.15 g per kg body weight; or III, NaHCO3 0.30 g per kg body weight. The sixth work bout was continued until the pedal velocity dropped below 50 rev min-1. Total work done for the entire work period was calculated. Blood samples were taken from a forearm vein prior to the exercise bouts for analysis of pH and HCO3. The results showed a significant pre-exercise difference in pH and HCO3 for all conditions (P less than 0.01). In conditions where artificial alkalosis had been achieved prior to exercise there was significant increase in the work produced: I, 121.6 kJ; II, 133.1 kJ; III, 133.5 kJ (P less than 0.05). The time to fatigue in the six bout was also significantly increased; I, 74.7 s; II, 111.0 s; III, 106.0 p (P less than 0.05). There were no significant differences between conditions II and III. Thus augmentation of the bicarbonate reserves has a significant positive effect on the energy metabolism in interval-type exercise, leading to an increase in the work done and in the time to fatigue.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Young adult soccer players often encounter difficulty progressing from youth competition to being regularly selected for high-level, open-age competition. In an attempt to increase the playing opportunities of semi-professional and amateur under-21 players in first teams, the Royal Belgian Football Association required national division teams to include at least two players younger than 21 in their match selection (under-21 rule). Over four seasons, the following variables were analysed across 2138 semi-professional and amateur soccer players aged 16-39 years: (1) the number of times a player was selected to be in the first team squad; (2) the number of times a player was selected to play in the starting line-up; and (3) the number of minutes played. Chi-square analysis demonstrated that second and third division teams had complied with the new selection regulations. However, two-way analysis of variance of individual player data revealed no increase in the number of playing minutes in the under-21 group. It would appear that many teams had complied with the new regulations by selecting young players as substitutes. The results highlight the difficulties that talented young soccer players experience progressing from youth to senior competition. We conclude that the rule imposed by the Royal Belgian Football Association has failed to improve the playing opportunities of young adult soccer players. Alternative strategies for increasing playing opportunities for young talented players are required. 相似文献
215.
The Urban Review - This work selects a political cite in which the state policy reform occurs to examine reasons and underlying ideologies for some consensus on the debates regarding the need to... 相似文献
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This study examined undergraduate and graduate students’ perceptions of the impact of in-class learning activities, out-of-class learning activities, and instructional materials on their learning. Using survey methodology, students anonymously assessed their perceptions of in-class activities, out-of-class activities, and instructional materials as most impactful, helpful, and enjoyable to their learning. Undergraduate college students found Jeopardy games, PowerPoint slides, and checking for understanding/review questions to be most helpful, while 50% often perceived Jeopardy games, Poll Everywhere, videos, and PowerPoint slides as enjoyable active learning strategies. Graduate students perceived small groups, out-of-class writing assignments, and Lino as most helpful to their learning. Additionally, an analysis of student comments about why these strategies were impactful, helpful, and enjoyable revealed 4 themes: fun, learning collaboratively, challenging but helpful, and variety in how students learn. Creating a learner-centered environment that is engaging as well as enjoyable for students positively impacts perceptions of students’ learning, which should encourage teachers to adopt this approach in their own college classrooms. 相似文献
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Using Necessary Information to Identify Item Dependence in Passage-Based Reading Comprehension Tests
Applications of traditional unidimensional item response theory models to passage-based reading comprehension assessment data have been criticized based on potential violations of local independence. However, simple rules for determining dependency, such as including all items associated with a particular passage, may overestimate the dependency that actually exists among the items. The current study proposed a more refined method based on cognitive principles and substantive theories to determine those items that pose a threat. Specifically, the use of common necessary information from text was examined as a contributor of local dependence. Cognitively similar item pairs, those with connected necessary information, had higher local dependence values than item pairs with no connected necessary information. Results suggest that focusing on necessary information may be useful to some extent for understanding and managing item dependence for passage-based reading comprehension tests. 相似文献