867 resultados para tennis players


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Objective: To demonstrate the utility of a practical measure of lean mass for monitoring changes in the body composition of athletes. Methods: Between 1999 and 2003 body mass and sum of seven skinfolds were recorded for 40 forwards and 32 backs from one Super 12 rugby union franchise. Players were assessed on 13 (7) occasions ( mean (SD)) over 1.9 (1.3) years. Mixed modelling of log transformed variables provided a lean mass index (LMI) of the form mass/skinfolds(x), for monitoring changes in mass controlled for changes in skinfold thickness. Mean effects of phase of season and time in programme were modelled as percentage changes. Effects were standardised for interpretation of magnitudes. Results: The exponent x was 0.13 for forwards and 0.14 for backs ( 90% confidence limits +/- 0.03). The forwards had a small decrease in skinfolds ( 5.3%, 90% confidence limits +/- 2.2%) between preseason and competition phases, and a small increase ( 7.8%, 90% confidence limits +/- 3.1%) during the club season. A small decrease in LMI (similar to 1.5%) occurred after one year in the programme for forwards and backs, whereas increases in skinfolds for forwards became substantial (4.3%, 90% confidence limits +/- 2.2%) after three years. Individual variation in body composition was small within a season (within subject SD: body mass, 1.6%; skinfolds, 6.8%; LMI, 1.1%) and somewhat greater for body mass (2.1%) and LMI (1.7%) between seasons. Conclusions: Despite a lack of substantial mean changes, there was substantial individual variation in lean mass within and between seasons. An index of lean mass based

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The purpose of this study was to characterize sprint patterns of rugby union players during competition. Velocity profiles (60 m) of 28 rugby players were initially established in testing from standing, walking, jogging, and striding starts. During competition, the individual sprinting patterns of 17 rugby players were determined from video by using the individual velocity profiles. Forwards commenced sprints from a standing start most frequently (41%), whereas backs sprinted from standing (29%), walking (29%),jogging (29%), and occasionally striding (13%) starts. Forwards and backs achieved speeds in excess of 90% maximal velocity (Vmax) on 5 +/- 4 and 9 +/- 4 occasions (similar to 50% of the sprints performed), respectively, during competition. The higher frequency of sprinting for the backs compared with the forwards highlights the importance of speed training for this positional group. The similar relative distribution of velocities achieved during competition for forwards and backs suggests both positional groups should train acceleration and Vmax qualities. The backs should have a higher total volume of sprint training. Sprinting efforts should be performed from a variety of starting speeds to mimic the movement patterns of competition.

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Email is an important form of asynchronous communication. Visualizing analyses of email communication patterns during a collaborative activity help us better understand the nature of collaboration, and identify the key players. By analysing the contents of email communication and adding reflective comments on its perceived importance from the participants of a collaboration new information can be gleaned not immediately obvious in its original flat form. This paper outlines a proof-of-concept prototype collaborative email visualisation schema. Data from a collaboration case study is analysed and subsequently employed to construct a display of the relative impact of both key players and the types of email used.

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Recent reports about procurement within the NHS have been highly critical. One problem identified in the reports is the fragmentation of NHS demand across an unnecessarily large number of suppliers. This fragmentation is said to increase transaction costs, reduce opportunities for scale economies and reduce NHS leverage over suppliers. It has been suggested, therefore, that an important way of improving procurement in the NHS is the better consolidation of demand with a lower number of preferred suppliers. However, such a policy, because it will create ‘winners’ and ‘losers’ within NHS organisations, has political as well as technical and practical ramifications. In this article, the authors present a model, the Veto Players Model, in order to assist managers to address these political ramifications. In the article, the authors not only demonstrate the utility of this model with regard to demand consolidation policies, but also argue that the model provides useful lessons for change management initiatives more generally.

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The purpose of the study was to determine whether voluntary acute or chronic dehydration occurs in a male adolescent athletic population during twicea- day American football practice sessions. We conclude that participants will voluntarily rehydrate themselves between practice sessions and will begin to acclimate within three to four days.

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General note: Title and date provided by Bettye Lane.

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General note: Title and date provided by Bettye Lane.