The effect of beetroot juice supplementation on repeat-sprint performance in hypoxia     

Georgina L. Kent  Brian Dawson  Lars R. McNaughton  Gregory R. Cox  Louise M. Burke  Peter Peeling 《Journal of sports sciences》2019,37(3):339-346

This investigation assessed the effect of dietary nitrate (NO₃^?) supplementation, in the form of beetroot juice (BR), on repeat-sprint performance in normoxia and normobaric hypoxia. 12 male team-sport athletes (age 22.3 ± 2.6 y, VO_2peak 53.1 ± 8.7 mL.kg^?1.min^?1) completed three exercise trials involving a 10 min submaximal warm-up and 4 sets of cycling repeat-sprint efforts (RSE; 9 × 4 s) at sea level (CON), or at 3000 m simulated altitude following acute supplementation (140 mL) with BR (HYP_BR; 13 mmol NO₃^?) or NO₃^–depleted BR placebo (HYP_PLA). Peak (PPO) and mean (MPO) power output, plus work decrement were recorded during the RSE task, while oxygen consumption (VO₂) was measured during the warm-up. There were no significant differences observed between HYP_BR and HYP_PLA for PPO or MPO; however, work decrement was reduced in the first RSE set in HYP_BR compared with HYP_PLA. There was a moderate effect for VO₂ to be lower following BR at the end of the 10 min warm-up (ES = 0.50 ± 0.51). Dietary NO₃^? may not improve repeat-sprint performance in hypoxia but may reduce VO₂ during submaximal exercise. Therefore, BR supplementation may be more effective for performance improvement during predominantly aerobic exercise.  相似文献   

NiCo_2O_4纳米结构阵列的水热合成与氧析出特性研究     

陈传胜  张作胜  陈伟杰  乔浏 《安徽职业技术学院学报》2020,(1):16-19,41

钴酸镍纳米材料具有良好的电催化氧析出反应(Oxygen Evolution Reaction,OER)活性,是一种很有发展潜力的非贵金属电催化材料。文章以碳纤维纸为基底,采用水热合成的方法对纳米结构钴酸镍的生长进行了系统的研究,分别考察了生长温度、前驱体浓度和配比、生长时间对产物的形貌、尺寸、物相结构、OER电化学性能的影响,通过对比分析后发现在生长温度100℃、生长时间5h、镍钴比为2:1时所获得的多孔片状钴酸镍纳米结构具有最佳的OER特性。  相似文献   

离岸集装箱码头新装卸工艺模式下陆域集疏运堆场堆存空间分配     

杨晓斌  余思勤  沈一帆 《上海海事大学学报》2020,41(4):8-14

离岸集装箱码头因其岛屿面积限制，难以通过扩建码头内部堆场增加吞吐能力。为解决这个问题，提出一种离岸集装箱码头新装卸工艺模式。新装卸工艺模式是通过在离岸集装箱码头附近的陆域地带建设陆域集疏运堆场,与离岸集装箱码头进行协同装卸作业的模式。陆域集疏运堆场堆存空间分配的目标是满足离岸集装箱码头装卸作业预翻倒要求;单批次输送集装箱的量受到陆岛运输最大通行能力限制。根据上述目标与特点，构建新装卸工艺模式下陆域集疏运堆场堆存空间分配模型，并设计蒙特卡洛树搜索算法进行求解。通过算例分析验证模型的有效性。结果表明该方法能够满足陆域集疏运堆场堆存空间分配需求并提高离岸集装箱码头的吞吐能力。  相似文献   

3-min all-out effort on cycle ergometer is valid to estimate the anaerobic capacity by measurement of blood lactate and excess post-exercise oxygen consumption     

Alessandro Moura Zagatto  Paulo Eduardo Redkva  Rodrigo Araújo Bonetti de Poli  Joel Abraham Martinez González  Jeniffer Zanetti Brandani  Thiago Penedo 《European Journal of Sport Science》2019,19(5):645-652

The purpose of this study was to investigate the use of a single 3-min all-out maximal effort to estimate anaerobic capacity (AC) through the lactate and excess post-exercise oxygen consumption (EPOC) response methods (AC_{[La^?]+EPOCfast}) on a cycle ergometer. Eleven physically active men (age?=?28.1?±?4.0?yrs, height?=?175.1?±?4.2?cm, body mass?=?74.8?±?11.9?kg and ?O_2max?=?40.7?±?7.3?mL?kg^?1?min^?1), participated in the study and performed: i) five submaximal efforts, ii) a supramaximal effort at 115% of intensity of ?O_2max, and iii) a 3-min all-out maximal effort. Anaerobic capacity was estimated using the supramaximal effort through conventional maximal accumulated oxygen deficit (MAOD) and also through the sum of oxygen equivalents from the glycolytic (fast component of excess post-exercise oxygen consumption) and phosphagen pathways (blood lactate accumulation) (AC_{[La^?]+EPOCfast}), while during the 3-min all-out maximal effort the anaerobic capacity was estimated using the AC_{[La^?]+EPOCfast} procedure. There were no significant differences between the three methods (p?>?0.05). Additionally, the anaerobic capacity estimated during the 3-min all-out effort was significantly correlated with the MAOD (r?=?0.74; p?=?0.009) and AC_{[La^?]+EPOCfast} methods (r?=?0.65; p?=?0.029). Therefore, it is possible to conclude that the 3-min all-out effort is valid to estimate anaerobic capacity in physically active men during a single cycle ergometer effort.  相似文献   

Effects of periodic carbohydrate ingestion on endurance and cognitive performances during a 40-km cycling time-trial under normobaric hypoxia in well-trained triathletes     

Yi-Hung Liao  Toby Mündel  Yan-Ting Yang  Chen-Chan Wei  Shiow-Chwen Tsai 《Journal of sports sciences》2019,37(16):1805-1815

The purpose of this study was to examine CHO ingestion on a cognitive task using a field-simulated time-trial (TT) under hypoxia in well-trained triathletes. Ten male triathletes (age: 22.1 ± 1.1 years; VO₂max: 59.4 ± 1.4 ml/kg/min) participated in this double-blind/crossover/counter-balanced design study. Participants completed 3 TT trials: 1) normoxic placebo (NPLA; FiO₂ = 20.9%), 2) hypoxic placebo (HPLA; FiO₂ = 16.3%), and 3) hypoxic CHO (HCHO; 6% CHO provided as 2 ml/kg/15 min; FiO₂ = 16.3%). During the TT, physiological responses (SpO₂, HR, RPE, and blood glucose/lactate), cognitive performance, and cerebral haemodynamics were measured. Hypoxia reduced TT performance by ~3.5–4% (p < 0.05), but CHO did not affect TT performance under hypoxia. For the cognitive task, CHO slightly preserved exercise-induced cognitive reaction speed but did not affect response accuracy during hypoxic exercise. However, CHO did not preserve the decreased Hb-Diff (cerebral blood flow, CBF) and increased HHb in the prefrontal lobe (p < 0.05) during hypoxic exercise, and CHO failed to preserve hypoxia-suppressed prefrontal CBF and tissue oxygen saturation. In conclusion, the present study demonstrates that CHO is effective in sustaining reaction speed for a cognitive task but not promoting TT performance during hypoxic exercise, which would be important for strategy-/decision-making when athletes compete at moderate high-altitude.  相似文献   

几种沉水植物光合作用产氧量的比较观察     

蒋梅兰  高枫 《台州学院学报》2001,(6)

在相同条件下,对几种不同沉水植物光合作用产氧量进行了比较观察。结果表明:金鱼藻、竹叶眼子菜是进行光合作用产氧量实验的好材料。  相似文献   

非蛋白呼吸商中糖和脂肪氧化百分比类型的确定     

冉辉 《铜仁学院学报》2002,4(4):77-80

非蛋白呼吸商是生理学中的一个重要概念，指的是糖的脂肪体内氧化时放出的CO2量与消耗的O2量的比值。对应不同的非蛋白呼吸商，糖和脂肪氧化的百分比不同。本通过定量计算分析表明，糖和脂肪氧化百分比既不是质量百分比，也不是放能百分比，而是耗氧百分比。  相似文献   

人才资源国际流动的趋衡性分析     

冯慰荣  冼国明 《中国软科学》2003,(10):101-105

随着经济全球化进程的加快,各国间的人才资源流动不断加剧。人才资源国际流动对于不同国家之间和不同时间区间的情况是不同的,是一个复杂的过程。本文假设在全球范围人才资源自由流动的市场条件下,从宏观上定性研究人才资源国际流动的趋衡性,对人才资源国际流动随时间变化的过程进行分析,探讨人才资源国际流动的规律,并由此分析我国人才资源流动的状况。  相似文献   

微孔硅酸钙干燥相关物理量的研究     

林建海  蒋智敏 《科技通报》1994,10(5):306-311

介绍了一些干燥相关物理量的研究方法，并对微孔硅酸钙的干燥相关物理量进行了初步的研究．根据电子扫描电镜的成象分析，获得了该种材料内部结构的固有规律，并在此基础上通过理论分析和一些简单的实验相结合的方法，得到了诸如微孔硅酸钙的多孔率、毛细压力和解吸等温线等物理量，为进一步深入研究微孔硅酸钙的干燥特性提供了依据．  相似文献   

一维同核化学位移相关谱的研究及其应用     

许小平 《科技通报》1994,10(2):105-105

从理论上分析研究了一维同核化学位移相关谱，并采用单片微处理机技术，首次在ＪＥＯＬＦＸ９０Ｑ核磁共振波谱仪上建立了一维同核化学位移相关谱方法，成功地测定了一些化合物的一维同核化学位移相关谱，得到了较好的结果。  相似文献