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Knechtle B Knechtle P Wirth A Alexander Rüst C Rosemann T 《Journal of sports sciences》2012,30(11):1131-1140
In 219 recreational male runners, we investigated changes in body mass, total body water, haematocrit, plasma sodium concentration ([Na(+)]), and urine specific gravity as well as fluid intake during a 100-km ultra-marathon. The athletes lost 1.9 kg (s = 1.4) of body mass, equal to 2.5% (s = 1.8) of body mass (P < 0.001), 0.7 kg (s = 1.0) of predicted skeletal muscle mass (P < 0.001), 0.2 kg (s = 1.3) of predicted fat mass (P < 0.05), and 0.9 L (s = 1.6) of predicted total body water (P < 0.001). Haematocrit decreased (P < 0.001), urine specific gravity (P < 0.001), plasma volume (P < 0.05), and plasma [Na(+)] (P < 0.05) all increased. Change in body mass was related to running speed (r = -0.16, P < 0.05), change in plasma volume was associated with change in plasma [Na(+)] (r = -0.28, P < 0.0001), and change in body mass was related to both change in plasma [Na(+)] (r = -0.36) and change in plasma volume (r = 0.31) (P < 0.0001). The athletes consumed 0.65 L (s = 0.27) fluid per hour. Fluid intake was related to both running speed (r = 0.42, P < 0.0001) and change in body mass (r = 0.23, P = 0.0006), but not post-race plasma [Na(+)] or change in plasma [Na(+)] (P > 0.05). In conclusion, faster runners lost more body mass, runners lost more body mass when they drank less fluid, and faster runners drank more fluid than slower runners. 相似文献
175.
Expert performers in striking sports can hit objects moving at high speed with incredible precision. Exceptionally well developed anticipation skills are necessary to cope with the severe constraints on interception. In this papr we provide a review of the empirical evidence regarding expert interception in striking sports and propose a preliminary model of expert anticipation. Central to the review and the model is the notion that the visual information used to guide the sequential phases of the striking action is systematically different between experts and nonexperts. Knowing the factors that contribute to expert anticipation, and how anticipation may guide skilled performance in striking sports, has practical implications for assessment and training across skill levels. 相似文献
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Will synthetic biology elicit controversies similar to those of genetically modified crops before? Maybe, but where exactly are the analogies, and how can we gain substantial insights rather than mere guesses? We argue that as well as the intrinsic properties of the technologies at stake, the context of their implementation is decisive. To assess mechanisms of past and potential controversies, an investigative tool is presented. The Gate Resonance model, derived from older models of societal conflict, allows the identification of key elements of conflict generating processes. In monitoring the developing debate on synthetic biology using this model, analogies to the case of genetically modified crops appear less convincing. So far, there are only few indications that a controversy is imminent. 相似文献
178.
Schmitt KU Wider D Michel FI Brügger O Gerber H Denoth J 《Sports biomechanics / International Society of Biomechanics in Sports》2012,11(1):57-72
Wrist injuries are frequently observed after falls in snowboarding. In this study, laboratory experiments mimicking forward and backward falls were analysed. In six different falling scenarios, participants self-initiated falls from a static initial position. Eighteen volunteers conducted a total of 741 trials. Measurements were taken for basic parameters describing the kinematics as well as the biomechanical loading during impact, such as impact force, impact acceleration, and velocity. The effective mass affecting the wrist in a fall also was determined. The elbow angle at impact showed a more extended arm in backward falls compared to forward falls, whereas the wrist angle at impact remained similar in forward and backward falls. The study results suggest a new performance standard for wrist guards, indicating the following parameters to characterize an impact: an effective mass acting on one wrist of 3-5 kg, an impact angle of 75 degrees of the forearm relative to the ground, and an impact velocity of 3 m/s. 相似文献
179.
This paper demonstrates how the application of New Public Management (NPM) and the accompanying rise of academic capitalism
in allocating research funds in the German academic field have interacted with a change from federal pluralism to a more stratified
system of universities and departments. From this change, a tendency to build cartel-like structures of allocating symbolic
capital resulting in oligopolistic structures of appropriating research funds has emerged. This macro level structure is complemented
by the strengthening of the traditional oligarchic structures of research, carried out by an increasing number of assistants
under the direction of a professor on the meso level. The outcome of this institutional setting is a significant gap between
the appropriation of research funds according to the allocation of symbolic capital and the production of knowledge in publications.
The application of NPM therefore needs to be explained more as a result of the normative pressure of a globally established
model of “rational” administration, and less as a result of its functional effectiveness. This is demonstrated by an empirical
analysis with simple and multiple regressions using data on the allocation of research grants and publication records of German
chemistry departments. 相似文献
180.
In this study, passive samplers were used to measure ozone exposure distribution maps over the historical peninsula of Istanbul, Turkey. The study area is partially important due to the presence of cultural and historical buildings and structures distributed all over the peninsula. Unesco's World Heritage list covers four zones located in this historical peninsula in Istanbul. It is necessary to evaluate the pollution distribution in high resolution to construct effective risk management strategies. For this purpose, 50 sampling stations were installed within the study area. Three sampling campaigns within different seasons (summer, winter and fall) showing different ozone distribution characteristics were carried out. Seasonal measurements of ozone exposure values were used to obtain a yearly exposure level, which is an important part of risk characterization. Seasonal ozone exposure maps over the historical peninsula were obtained using Geographical Information Systems (GIS) based interpolation models with high resolution. Risk maps including five regions, based on ozone exposure levels were created. Structures and historical regions located within these risk zones were identified. Based on the defined exposure regions, we found that the Archaeological Park, one of the items on UNESCO's list, is located within the most risky region. 相似文献