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Physical and metabolic demands of training and match-play in the elite football player 总被引：2，自引：0，他引：2
In soccer, the players perform intermittent work. Despite the players performing low-intensity activities for more than 70% of the game, heart rate and body temperature measurements suggest that the average oxygen uptake for elite soccer players is around 70% of maximum (VO(2max). This may be partly explained by the 150 - 250 brief intense actions a top-class player performs during a game, which also indicates that the rates of creatine phosphate (CP) utilization and glycolysis are frequently high during a game. Muscle glycogen is probably the most important substrate for energy production, and fatigue towards the end of a game may be related to depletion of glycogen in some muscle fibres. Blood free-fatty acids (FFAs) increase progressively during a game, partly compensating for the progressive lowering of muscle glycogen. Fatigue also occurs temporarily during matches, but it is still unclear what causes the reduced ability to perform maximally. There are major individual differences in the physical demands of players during a game related to physical capacity and tactical role in the team. These differences should be taken into account when planning the training and nutritional strategies of top-class players, who require a significant energy intake during a week. 相似文献
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Andrea Giorgi Maurizio Vicini Luca Pollastri Erica Lombardi Emilio Magni Andrea Andreazzoli 《Journal of sports sciences》2018,36(22):2608-2613
Bioelectrical impedance vector-analysis (BIVA) describes cell-mass, cell function and hydration status of an individual or a group. The goal of the present investigation was to provide bioelectrical impedance data for 525 male road cyclists (155 professionals, 79 elite, 59 elite-youth, and 232 amateurs) at the time of their optimal performance level. Data were plotted on the resistance-reactance (R-Xc) graph to characterize cyclists group vectors using BIVA. Compared to the general male population, the mean vector position of the road cyclists indicates a higher body cell mass (BCM) and phase angle (p<0.001). The vector position of the high-performance, compared to the amateur cyclists showed similar patterns with higher BCM and phase angles and higher reactance values for the high-performance athletes (p<0.001). The bio-impedance data were used to calculate the 50%, 75%, and 95% tolerance ellipses of each group of cyclists. The characteristic vector positions of the road cyclists indicate normal hydration and greater muscle mass and function of the high-performance cyclists compared to amateur cyclists and the normal population. The cyclists specific tolerance ellipses, particularly the high-performance cyclists might be used for classifying a cyclist according to the individual vector position and to define target vector regions for lower level cyclists. 相似文献
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Phillip J. Mohr 《Communication Studies》2013,64(4):342-351
This article examines two implicit assumptions on which the family viewing concept appears to be based: (1) children's viewing will subside after the end of the family viewing period, and children will be less likely to be exposed to later, more “mature” programming; (2) broadcasters can and do provide programs toward which children and parents share preferences and which are “appropriate” for the family viewing period (6:00‐8:00 p.m. CST, 7:00‐9:00 in other time zones). Data gathered in a 1976 survey confirmed the first assumption. However, while the peak period of children's viewing occurred between 6:30 and 8:00 p.m., substantial numbers of the children continued to view television beyond the family viewing period. Less consistent support was found for the second assumption. Above‐average percentages of both parents and children considered thirty‐one of sixty‐eight programs listed on the questionnaires to be “favorites” or “all right,” and nineteen of the thirty‐one were broadcast during the family viewing period. While parents and children may share attitudes toward certain programs, however, it does not necessarily follow that parents consider those programs appropriate for their children. The results of the survey suggest the need for further study of what constitutes “appropriate” programming for family viewing. 相似文献
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The role of team behavioral integration and cohesion in shaping individual improvisation 总被引：2，自引：0，他引：2
The notion of improvisation has recently emerged in managerial studies as a viable answer to flexibly dealing with unexpected occurrences. Nonetheless, research on improvisation has essentially approached the issue through a metaphorical framework, and has regularly relied on conceptual frameworks residing either at the individual or the team-level. We investigate how team-level processes affect individual improvisation in complex project domains. Using data from 138 team leaders and members belonging to 38 information systems development teams, we test cross-level hypotheses through hierarchical linear modeling. Team behavioral integration and team cohesion positively affect individual improvisation. Moreover, cohesion positively moderates the influence of team behavioral integration on individual improvisation. In concluding this paper we offer theoretical and practical implications. 相似文献
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