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31.
The effect of wet suit use by triathletes: an analysis of the different phases of arm movement 总被引：1，自引：0，他引：1
We analysed stroke phases and arm and leg coordination during front crawl swimming with and without a wet suit. Twelve nationally and internationally ranked French male triathletes performed three swim trials in randomized order using the front crawl stroke with and without a wet suit. All triathletes swam at three different swim velocities, corresponding to the paces appropriate for the 800 m (V800), 100 m (V100) and 50 m (V50) events. The different stroke phases and arm and leg coordination were identified by video analysis. Arm coordination was quantified using a new index of coordination, which expresses the three major modalities of opposition, catch-up and superposition in swimming. At all swim velocities, no significant differences in leg movements with or without the wet suit were noted. However, the wearing of the wet suit was associated with a significantly greater stroke length at the paces appropriate for the 100 and 50 m events (+3.46% and +3.10% at V100 and V50, respectively; P<0.01); a significantly greater stroke index at all three velocities (+5.18%, +5.21% and +5.91% at V800, V100 and V50, respectively; P<0.01); a significantly shorter pulling phase (-10.97%; P<0.05) and lower index of coordination (-21.87%; P<0.01) at the pace appropriate for the 800 m; and a significantly greater entry and catch phase (+9.81%; P<0.05) at the pace appropriate for the 100 m. We conclude that the wet suit amplified the coordination mode of the triathletes (i.e. catch-up coordination) without modifying stroke rate, recovery phase or leg movements. 相似文献
32.
As noted by Fremer and Olson, analysis of answer changes is often used to investigate testing irregularities because the analysis is readily performed and has proven its value in practice. Researchers such as Belov, Sinharay and Johnson, van der Linden and Jeon, van der Linden and Lewis, and Wollack, Cohen, and Eckerly have suggested several statistics for detection of aberrant answer changes. This article suggests a new statistic that is based on the likelihood ratio test. An advantage of the new statistic is that it follows the standard normal distribution under the null hypothesis of no aberrant answer changes. It is demonstrated in a detailed simulation study that the Type I error rate of the new statistic is very close to the nominal level and the power of the new statistic is satisfactory in comparison to those of several existing statistics for detecting aberrant answer changes. The new statistic and several existing statistics were shown to provide useful information for a real data set. Given the increasing interest in analysis of answer changes, the new statistic promises to be useful to measurement practitioners. 相似文献
33.
目的 观察大鼠实验性胃溃疡期间大脑皮层生长抑素免疫反应(SS-ir)和SSmRNA神经元的变化。方法 免疫细化PAP法;地高辛标记反意SScRNA探针mRNA原位杂交组化法。结果 正常大鼠SS-ir神经元广泛分布于大脑皮层。溃疡术后1d,大脑皮层纹状皮质区各层SS-ir神经元减少,但可见大量串珠样SS强阳性纤维,溃疡组SS-ir神经元数与盐水组相比无差异;术后4d,溃疡组大脑皮层纹状皮质区各层SS-ir神经元密集、数量明显增多,与盐水组、正常组相比均有差异(P<0.05,P<0.01或P<0.001)。术后10和23d,以上核区SS-ir神经元数仍高于盐水组和正常组(P<0.01,P<0.001)。术后4d,溃疡组大脑皮层SSmRNA神经元数量明显多于盐水组(P<0.001)。结论 大鼠实验性胃溃疡时期,大脑皮层SS-ir和SSmRNA神经元可能参与了胃溃疡自愈过程的调节。 相似文献