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11.
Giovani Cunha Thiago Lorenzi Katiuce Sapata Andre Luiz Lopes Adroaldo Cezar Gaya 《Journal of sports sciences》2013,31(10):1029-1039
Abstract In this study, we investigated the effect of biological maturation on maximal oxygen uptake ([Vdot]O2max) and ventilatory thresholds (VT1 and VT2) in 110 young soccer players separated into pubescent and post-pubescent groups.. Maximal oxygen uptake and [Vdot]O2 corresponding to VT1 and VT2 were expressed as absolute values, ratio standards, theoretical exponents, and experimentally observed exponents. Absolute [Vdot]O2 (ml · min?1) was different between groups for VT1, VT2, and [Vdot]O2max. Ratio standards (ml · kg?1 · min?1) were not significantly different between groups for VT1, VT2, and [Vdot]O2max. Theoretical exponents (ml · kg?0.67 · min?1 and ml · kg?0.75 · min?1) were not properly adjusted for the body mass effects on VT1, VT2, and [Vdot]O2max. When the data were correctly adjusted using experimentally observed exponents, VT1 (ml · kg?0.94 · min?1) and VT2 (ml · kg?0.95 · min?1) were not different between groups. The experimentally observed exponent for [Vdot]O2max (ml · kg?0.90 · min?1) was different between groups (P = 0.048); however, this difference could not be attributed to biological maturation. In conclusion, biological maturation had no effect on VT1, VT2 or [Vdot]O2max when the effect of body mass was adjusted by experimentally observed exponents. Thus, when evaluating the physiological performance of young soccer players, allometric scaling needs to be taken into account instead of using theoretical approaches. 相似文献
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Scott K. Powers Stephen Dodd Richard Deason Ronald Byrd Tipton Mcknight 《Research quarterly for exercise and sport》2013,84(2):179-182
Abstract The purpose of this study was to assess the relationships among ventilatory threshold T(vent), running economy and distance running performance in a group (N=9) of trained experienced male runners with comparable maximum oxygen uptake ([Vdot]O2 max). Maximal oxygen uptake and submaximal steady state oxygen uptake were measured using open circuit spirometry during treadmill exercise. Ventilatory threshold was determined during graded treadmill exercise using non-invasive techniques, while distance running performance was assessed by the best finish time in two 10-kilometer (km) road races. The subjects averaged 33.8 minutes on the 10km runs, 68.6 ml · kg -1 · min -1 for [Vdot]O2 max, and 48.1 ml · kg -1 · min -1 for steady state [Vdot]O2 running at 243 meters · min -1. The T(vent) (first deviation from linearity of [Vdot]E, [Vdot]CO 2 ) occurred at an oxygen consumption of 41.9 ml · kg -1 · min -1. The relationship between running economy and performance was r = .51 (p>0.15) and the relationship between T(vent) and performance was r = .94 (p < 0.001). Applying stepwise multiple linear regression, the multiple R did not increase significantly with the addition of variables to the T(vent); however, the combination of [Vdot]O2 max, running economy and T(vent) was determined to account for the greatest amount of total variance (89%). These data suggest that among trained and experienced runners with similar [Vdot]O2 max, T(vent) can account for a large portion of the variance in performance during a 10km race. 相似文献
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Elaine Wilson 《Educational Action Research》2013,21(4):587-612
The development of beginning teachers' practice during a school placement is a multiplicity of mediated interactions between university- and school-based systems. Both systems have the common aim of training effective teachers. However, day-to-day internal institution matters can cause tension between the learning goals set out for the beginning teacher by the university and the schools' drive to ensure maximum student performance in ‘high stake’ national tests. This article reports on an intervention intended to equip beginning teachers with the capacity to learn, through purposive activity, in an authentic classroom environment. The context of the learning was to address the conceptual difficulties that secondary school pupils (aged 11-16) have in understanding scientific concepts within the constraints of a ‘curriculum delivery’ lead culture. The results show that beginning teachers are able to extract principles, which might assist them in new contexts in the future. The interactions which took place during the intervention within a school University Initial Teacher Education and Training partnership were analysed using activity systems. 相似文献
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Dawn Scott 《Journal of sports sciences》2018,36(13):1523-1532
This study examined the utility of a range of approaches used to develop player-dependent speed zones in time-motion analysis (TMA), in determining the dose-response (internal load) of daily football training. Daily external (10 Hz GPS) and internal load (heart rate metrics, ratings of perceived exertion [RPE], wellness ratings) measures were tracked for 22 International women’s football players during a 21-day training camp. High-speed (HSR) and very high speed running (VHSR) were determined according to arbitrary speed thresholds, as well as using a range of different individualization approaches that included the velocities corresponding to the heart rate deflection point, maximal aerobic speed, YYIR1 performance, and maximal sprint speed (MSS). Within-player correlations between the TMA approaches versus internal load measures quantified the dose-response to training. Correlations between HSR and VHSR vs. RPE were large (r = 0.53–0.67), with the exception of VHSR for the MSS technique (moderate; r = 0.44). HSR was very-largely associated with heart rate indices (r = 0.72–0.78), again with the exception of MSS (large; r = 0.60–0.67). Using a range of different fitness characteristics to individualise speed thresholds did not enhance the dose-response determination to daily fluctuations in external load, and was worsened with MSS per se. 相似文献
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比较渐增负荷运动时,不同环境条件对血乳酸浓度、血乳酸阈值及血乳酸开始堆积（OBLA）的影响。8名身体健康的男大学生（非热适应者）参加实验,受试者在两种不同温度环境条件下（40和25C）,进行功率自行车渐增负荷运动。研究发现在高温条件下渐增负荷运动时,LT和OBLA发生向左偏移,同时认为在渐增负荷运动时,血乳酸的堆积并不是调节通气量（VE）的唯一因素,而且通气阈值（VT）也不能总是正确地反映LT。 相似文献
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Leonardo A. Pasqua Salomão Bueno Guilherme G. Artioli Antônio H. Lancha JR. Monique Matsuda Mônica V. Marquezini 《Journal of sports sciences》2016,34(2):163-170
The purpose of this study was to verify the association between ACTN3 polymorphism and physiological parameters related to endurance performance. A total of 150 healthy male volunteers performed a maximal incremental running test to determine the speeds corresponding to ventilatory threshold (VT) and respiratory compensation point (RCP). Participants were genotyped and divided into terciles based on the analysed variables. Genotype frequencies were compared through χ2 test between lower and higher terciles, with the lowest or highest values of each analysed variable. ACTN3 XX genotype was over-represented in higher tercile for VT and RCP. Odds ratio also showed significantly higher chances of XX individuals to be in higher tercile compared to RR (7.3) and RR + RX (3.5) for VT and compared to RR genotype (8.1) and RR + RX (3.4) for RCP. Thus, XX individuals could attain the VT and RCP at higher speeds, suggesting that they are able to sustain higher running speeds in lower exercise intensity domains. It could result in higher lipid acids oxidation, saving muscle glycogen and delaying the fatigue during prolonged exercises, which could be the advantage mechanism of this genotype to endurance performance. 相似文献
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《European Journal of Sport Science》2013,13(7):615-622
AbstractThe capacity to predict the heart rate (HR) and speed at the first (VT1) and second (VT2) ventilatory thresholds was evaluated during an incremental ski-mountaineering test using heart rate variability (HRV). Nine skiers performed a field test to exhaustion on an alpine skiing track. VT1 and VT2 were individually determined by visual analysis from gas exchanges (VT1V and VT2V) and time-varying spectral HRV analysis (VT1fH, VT2fH and VT2H). VT1 could not be determined with the HRV methods used. On the contrary, the VT2 was determined in all skiers. No significant difference between HR and speed at VT2H and VT2V was observed (174.3 ± 5.6 vs. 174.3 ± 5.3 bpm, and 6.3 ± 0.9 and 6.3 ± 0.9 km h–1, respectively). Strong correlations were obtained for HR (r = 0.91) and speed (r = 0.92) at VT2H and VT2V with small limits of agreement (±3.6 bpm for HR). Our results indicated that HRV enables determination of HR and speed at VT2 during a specific ski-mountaineering incremental test. These findings provide practical applications for skiers in order to evaluate and control specific training loads, at least when referring to VT2. 相似文献
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刘涛 《军事体育进修学院学报》2011,30(2):120-122
考察胸围与氧通气当量及其相关参数间的关系.受试者为197名汉族成年男性.测定其安静状态下胸围(平静呼气末)、身高、体重、肺通气量、摄氧量和氧通气当量.结果显示:在控制协变量前后,胸围皆与氧通气当量无关(所有P≥0.67);在控制协变量之前,胸围与肺通气量和摄氧量关联(所有P＜0.001),但在控制身体质量指数(BMI)... 相似文献
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彭家寅 《内江师范学院学报》2014,(12):1-8
利用模糊点与模糊集之重于关系,在BL-代数中引入了（∈,∈∨q）-模糊n-重蕴涵滤子的概念,推广了经典的模糊n-重蕴涵滤子,给出了（∈,∈∨q）-模糊n-重蕴涵滤子的一些刻画.研究了（∈,∈∨q）-模糊蕴涵滤子与（∈,∈∨q）-模糊n-重蕴涵滤子的关系、（∈,∈∨q）-模糊n-重蕴涵滤子与（∈,∈∨q）-模糊（n＋1）-重蕴涵滤子的关系.提出门限模糊n-重蕴涵滤子的概念,以此获得了非平凡的经典模糊n-重蕴涵滤子、非平凡的（∈,∈∨q）-模糊n-重蕴涵滤子,研究了门限模糊n-重蕴涵滤子和（∈,∈∨q）-模糊n-重蕴涵滤子的性质. 相似文献