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21.
On a kayak ergometer, an accurate simulation of the athlete-paddle-kayak system kinematics is essential for analysing the relationship between technique and performance. The purpose of this study
was to establish a strong relationship between performances on flatwater and performances on an ergometer by means of propulsive
force measurement and drag models. Two trials were performed by 12 kayakers in which they were first timed over 250 m of flatwater
kayaking (the reference test) and were then asked to perform a trial of the same duration on the ergometer with the same perceived
physical exertion. Three techniques for measuring propulsive force and three drag models generated nine combinations, which
were all evaluated for their ability to estimate kayak velocity. For each combination, the distance covered by the athlete
on the ergometer was simulated. A kayakers’ ergometer ranking was based on the average velocity in the ergometer trial. Both
distance and ranking were compared to the on-water results. The simulation with the best combination of force measurement
and drag model gave an accurate estimate of distance (253 ± 10.5 vs. 250 m) and ranking compared to the reference test. 相似文献
22.
Guillaume Costalat Jeremy Coquart Ingrid Castres Fabrice Joulia Olivier Sirost Eric Clua 《Journal of sports sciences》2017,35(7):678-687
We investigated the oxygen-conserving potential of the human diving response by comparing trained breath-hold divers (BHDs) to non-divers (NDs) during simulated dynamic breath-holding (BH). Changes in haemodynamics [heart rate (HR), stroke volume (SV), cardiac output (CO)] and peripheral muscle oxygenation [oxyhaemoglobin ([HbO2]), deoxyhaemoglobin ([HHb]), total haemoglobin ([tHb]), tissue saturation index (TSI)] and peripheral oxygen saturation (SpO2) were continuously recorded during simulated dynamic BH. BHDs showed a breaking point in HR kinetics at mid-BH immediately preceding a more pronounced drop in HR (?0.86 bpm.%?1) while HR kinetics in NDs steadily decreased throughout BH (?0.47 bpm.%?1). By contrast, SV remained unchanged during BH in both groups (all P > 0.05). Near-infrared spectroscopy (NIRS) results (mean ± SD) expressed as percentage changes from the initial values showed a lower [HHb] increase for BHDs than for NDs at the cessation of BH (+24.0 ± 10.1 vs. +39.2 ± 9.6%, respectively; P < 0.05). As a result, BHDs showed a [tHb] drop that NDs did not at the end of BH (?7.3 ± 3.2 vs. ?3.0 ± 4.7%, respectively; P < 0.05). The most striking finding of the present study was that BHDs presented an increase in oxygen-conserving efficiency due to substantial shifts in both cardiac and peripheral haemodynamics during simulated BH. In addition, the kinetic-based approach we used provides further credence to the concept of an “oxygen-conserving breaking point” in the human diving response. 相似文献
23.
Mauricio Garzon Olivier Dupuy Laurent Bosquet Anil Nigam Alain Steve Comtois Martin Juneau 《European Journal of Sport Science》2017,17(3):310-316
This study compared heart rate recovery (HRR) after incremental maximal exercise performed at the same external power output (Pext) on dry land ergocycle (DE) vs. immersible ergocycle (IE). Fifteen young healthy participants (30?±?7 years, 13 men and 2 women) performed incremental maximal exercise tests on DE and on IE. The initial Pext on DE was 25?W and was increased by 25?W/min at a pedalling cadence between 60 and 80?rpm, while during IE immersion at chest level in thermoneutral water (30°C), the initial Pext deployment was at a cadence of 40?rpm which was increased by 10?rpm until 70?rpm and thereafter by 5?rpm until exhaustion. Gas exchange and heart rate (HR) were measured continuously during exercise and recovery for 5?min. Maximal HR (DE: 176?±?15 vs. IE 169?±?12?bpm) reached by the subjects in the two conditions did not differ (P?>?.05). Parasympathetic reactivation parameters (ΔHR from 10 to 300?s) were compared during the DE and IE HR recovery recordings. During the IE recovery, parasympathetic reactivation in the early phase was more predominant (HRR at Δ10–Δ60?s, P?<?.05), but similar in the late phase (HRR at Δ120–Δ300?s, P?>?.05) when compared to the DE condition. In conclusion, incremental maximal IE exercise at chest level immersion in thermoneutral water accelerates the early phase parasympathetic reactivation compared to DE in healthy young participants. 相似文献
24.
Olivier Schalm Ine De Raedt Joost Caen Koen Janssens 《Journal of Cultural Heritage》2010,11(4):81-492
The chemical composition of 11 glass panes originating from two 13th century non-figurative windows were analyzed by means of Scanning Electron Microscopy–Energy Dispersive X-ray system (SEM-EDX). The windows were discovered in the back-wall of the triforium during the restoration of the choir of the cathedral St. Michael and St. Gudule in Brussels (Belgium). In order to determine if these windows were fabricated with glass of different origin or not, the compositional difference between the panes were compared with the variation in composition as a result of the following causes: (1) compositional fluctuation between panes cut from the same sheet of glass, (2) compositional fluctuation caused when panes are cut from different sheets that were made with the same batch, (3) compositional fluctuation caused when the glass is made from different batches at the same production center, and (4) compositional fluctuation as a result of glass produced at different fabrication centers. 相似文献
25.
26.
Raw scores on the 16 K-ABC subtests and the total raw scores on the sequential and simultaneous processing scales and the achievement scale were correlated with age in months for two separate samples, each subdivided by race and sex: the K-ABC standardization sample (N = 2000) and an additional group of blacks and whites tested during the development of the K-ABC sociocultural norms (N = 615). Within each sample, the highest and lowest correlations from all race/sex groups were contrasted across all K-ABC subtests and scales. All correlations between age and raw scores were statistically significant (p ⩽ .05). No significant differences occurred in the magnitude of these relationships as a function of race/sex grouping, supporting the construct validity of the K-ABC as a developmental measure of children's aptitude and achievement for blacks, whites, Hispanics, males, and females. 相似文献
27.
Abstract Past experience with an industrial, classroom‐based educational model for aboriginal students has revealed severe limitations that have resulted in secondary graduation levels far below those of the Canadian population in general. Distance education has the potential to redress many of the traditional model's inherent weaknesses, including the reduction of problems associated with cultural assimilation. Distance education also has the potential to enhance the multimedia resources of band‐controlled schools, schools that have shown good promise in raising retention and attainment rates. This article reviews the current situation pertaining to education in Canadian aboriginal communities, discusses the strengths and weaknesses of two distance education programs for aboriginals, and concludes with key guidelines for future distance education endeavors. 相似文献
28.
Urban information integration for advanced e-Planning in Europe 总被引:1,自引:0,他引:1
Hongxia Wang Yonghui Song Andy Hamilton Steve Curwell 《Government Information Quarterly》2007,24(4):736
Urban planning is a complex task requiring multidimensional urban information (spatial, social, economic, etc.). The need for assistance in performing urban planning tasks has led to the rapid development of urban information systems, especially “e-Planning” systems, with the support of government policy and emerging information and communication technologies (ICT). In order to enhance the capability of e-Planning and to facilitate 3D visualization and rich analysis of complex city problems, it is very important to allow information from the various sources to be shared and integrated. This paper focuses on technical approaches for multidimensional information integration, especially spatial information integration. In particular it describes the Building Data Integration System (BDIS), developed as part of the IntelCities project, which demonstrates the type of multidimensional systems that are likely to be used in future urban information systems. Functionally, the BDIS demonstrates the feasibility of systems to support the multinational collaboration of construction professionals in the procurement and renovation of buildings. For such systems to be accepted in the United Kingdom (UK) and Europe, they need to be developed with regard to current planning information structures and standards in the UK and Europe which are reviewed in this paper. The achievements and further development of multidimensional information integration through the use of innovative urban data modelling techniques are discussed. 相似文献
29.
30.
Larsen GE George JD Alexander JL Fellingham GW Aldana SG Parcell AC 《Research quarterly for exercise and sport》2002,73(1):66-72
The purpose of this study was to develop a submaximal, 1.5-mile endurance test for college-aged students using walking, jogging, or running exercise. College students (N = 101: 52 men, 47 women), ages 18-26years, successfully completed the 1.5-mile test twice, and a maximal graded exercise test. Participants were instructed to achieve a "somewhat hard" exercise intensity (rating of perceived exertion = 13) and maintain a steady pace throughout each 1.5-mile test. Multiple linear regression generated the following prediction equation: VO2 max = 65.404 + 7.707 x gender (1 = male; 0 =female) - 0.159 x body mass (kg) - 0.843 x elapsed exercise time (min; walking, jogging orrunning). This equation shows acceptable validity (R = .86, SEE = 3.37 ml x kg(-1) min(-1)) similar to the accuracy of comparable field tests, and reliability (ICC = .93) is also comparable to similar models. The statistical shrinkage is minimal (R(press) = 0.85, SEE(press) = 3.51 ml x kg(-) x min(-1)); hence, it should provide comparable results when applied to other similar samples. A regression model (R =.90, and SEE = 2.87 ml x kg(-1) min(-1)) including exercise heart rate was also developed: VO2 max = 100.162 +/- 7.301 x gender(1 = male; 0 =female) - 0.164 x body mass (kg) - 1.273 x elapsed exercise time -0.156 x exercise heart rate, for those who have access to electronic heart rate monitors. This submaximal 1.5-mile test accurately predicts maximal oxygen uptake (VO2max) without measuring heart rate and is similar to the 1.5-mile run in that it allowsfor mass testing and requires only a flat, measured distance and a stopwatch. Further, it can accommodate a wide range of fitness levels (from walkers to runners). 相似文献