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1.
“Crossover”概念可以解释耐力项目运动中,运动强度和耐力训练对糖、脂肪代谢平衡的影响。根据“Crossover”的概念:耐力训练引起肌肉的生化适应,增加脂肪的氧化供能。小强度运动(≤45% VO2 m ax)以脂肪供能为主,大强度运动(～75% VO2 m ax)糖是主要供能底物,即便是经过耐力训练也不例外。 相似文献
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糖是人体运动所需能量的主要来源,长时间大强度的耐力运动总热能的消耗将更加显著。本文从糖的有氧代谢补充大能量的角度来研究补糖对提高耐力运动的作用,主要论述了糖的分类与储存;运动时糖的摄取和利用;耐力运动中糖补充的种类、方式及时间。以便深入地研究耐力运动训练中补糖的正确方法,提高运动成绩,促进运动性疲劳的超量恢复。 相似文献
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在当前的体育训练和比赛中，中长跑等运动项目对速度耐力的要求越来越高。速度耐力项目的特点是以糖的有氧代谢供能为主，以力量为基础。糖在有氧、无氧情况下，都能分解并且供给能量，在三大供能物质（糖、蛋白质、脂肪）中，具有代谢快、氧消耗少的显著特性，因此糖类物质的补充在耐力训练和比赛中，相对蛋白质和脂肪类物质来说，对训练和比赛的贡献更大。 相似文献
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在一个月经周期中,女性体内激素和对物质代谢调节的变化对于运动能力有一定影响。关于月经周期对葡萄糖代谢动力学的研究发现,黄体期葡萄糖Ra和Rd降低,而且女性在卵泡期要比在黄体期耐力性运动的运动能力更为强一些。通过补糖可以使这种差异减小,建议女运动员如果在黄体期参加运动,尤其是耐力性运动,要注意保证摄入充足的糖。 相似文献
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长跑运动项目具有持续时间长、运动中无间歇及物质代谢以有氧氧化为主导的特点,因此膳食应提供足够的热能。耐力性项目运动员缺铁性贫血的发生率较高,因此应提供足够的蛋白质和铁。由于运动时间长,运动强度相对较低,运动员体内脂肪的动员和利用率高,所以应提供适量的脂肪。耐力运动中大量出汗使水分、电解质丢失,应适量补液,维生素的供给应随热能消耗量的增加而相应提高。 耐力运动员碳水化合物占总热量的比例应大于60％～70％。运动前、中、后适量补糖可以提高肌糖原水平,维持血糖于较高水平,使运动后的肌糖原尽快 相似文献
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1.哪一种食物是运动时的主要能源? 答:糖和脂肪是运动时的主要能源。在一般情况下,糖类(糖元和葡萄糖)是更重要的能源。但是在持续时间长达几小时的耐力运动中,脂肪也是十分重要的能源。已经证明,肌肉疲劳与肌糖源的耗竭在时间上是一致的。所以在任何情况下,保持一定的肌糖元贮备是很重要的。 2.运动训练之间需要多少时间才能充分恢复? 相似文献
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糖与耐力运动（综述） 总被引：4，自引：0，他引：4
糖与耐力运动有密切关系，机体的糖原贮备和血糖水平直接影响运动耐力。通过合理控制饮食糖的数量和种类以及运动前、中、后的适时补糖，可以增加（赛前）糖原贮备，降低运动中的糖原消耗和促进运动后糖原恢复。 相似文献
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摄入碳水化合物对机体利用肌糖元和运动成绩的影响 总被引：1，自引：0，他引：1
在超长时间运动中,血糖和肌糖元是运动肌利用的两种主要糖源。现在证实,肌糖元浓度是决定耐力运动能力的主要因素。通过摄入碳水化合物来提高超长时间运动中糖的利用率,这可能会延迟出现疲劳和提高耐力运动的成绩。但是,在超长时间运动中,摄入碳水化合物会对肌糖元的利用产生什么影响?有关这方面的论文目前还没有看到。由于过去这方面的研究都采用不定时、不定量地摄入碳水化合物的方法,因此本研究的目的是要查明在4 相似文献
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E. V. Lambert J. A. Hawley J. Goedecke T. D. Noakes S. C. Dennis 《Journal of sports sciences》2013,31(3):315-324
Carbohydrate ingestion before and during endurance exercise delays the onset of fatigue (reduced power output). Therefore, endurance athletes are recommended to ingest diets high in carbohydrate (70% of total energy) during competition and training. However, increasing the availability of plasma free fatty acids has been shown to slow the rate of muscle and liver glycogen depletion by promoting the utilization of fat. Ingested fat, in the form of long-chain (C 16-22 ) triacylglycerols, is largely unavailable during acute exercise, but medium-chain (C 8-10 ) triacylglycerols are rapidly absorbed and oxidized. We have shown that the ingestion of medium-chain triacylglycerols in combination with carbohydrate spares muscle carbohydrate stores during 2 h of submaximal (< 70% VO 2 peak) cycling exercise, and improves 40 km time-trial performance. These data suggest that by combining carbohydrate and medium-chain triacylglycerols as a pre-exercise supplement and as a nutritional supplement during exercise, fat oxidation will be enhanced, and endogenous carbohydrate will be spared. We have also examined the chronic metabolic adaptations and effects on substrate utilization and endurance performance when athletes ingest a diet that is high in fat (> 70% by energy). Dietary fat adaptation for a period of at least 2-4 weeks has resulted in a nearly two-fold increase in resistance to fatigue during prolonged, low- to moderate-intensity cycling (< 70% VO 2 peak). Moreover, preliminary studies suggest that mean cycling 20 km time-trial performance following prolonged submaximal exercise is enhanced by 80 s after dietary fat adaptation and 3 days of carbohydrate loading. Thus the relative contribution of fuel substrate to prolonged endurance activity may be modified by training, pre-exercise feeding, habitual diet, or by artificially altering the hormonal milieu or the availability of circulating fuels. The time course and dose-response of these effects on maximizing the oxidative contribution of fat for exercise metabolism and in exercise performance have not been systematically studied during moderate- to high-intensity exercise in humans. 相似文献
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A key goal of pre-exercise nutritional strategies is to maximize carbohydrate stores, thereby minimizing the ergolytic effects of carbohydrate depletion. Increased dietary carbohydrate intake in the days before competition increases muscle glycogen levels and enhances exercise performance in endurance events lasting 90 min or more. Ingestion of carbohydrate 3-4 h before exercise increases liver and muscle glycogen and enhances subsequent endurance exercise performance. The effects of carbohydrate ingestion on blood glucose and free fatty acid concentrations and carbohydrate oxidation during exercise persist for at least 6 h. Although an increase in plasma insulin following carbohydrate ingestion in the hour before exercise inhibits lipolysis and liver glucose output, and can lead to transient hypoglycaemia during subsequent exercise in susceptible individuals, there is no convincing evidence that this is always associated with impaired exercise performance. However, individual experience should inform individual practice. Interventions to increase fat availability before exercise have been shown to reduce carbohydrate utilization during exercise, but do not appear to have ergogenic benefits. 相似文献
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丙酮酸和二羟丙酮都是糖代谢过程中的三碳化合物。长期丙酮酸和二羟丙酮补充可以降低体脂和延缓体重获得,这种变化可能与体脂消耗和热量损失上升有关。丙酮酸和二羟丙酮补充也可以改善胰岛素敏感性和降低高胆固醇膳食所致的血浆胆固醇水平。另外,长期丙酮酸和二羟丙酮补充还可以提高有氧耐力成绩,其机制可能与血糖利用率增加因而节省肌糖元有关。长期补充丙酮酸和二羟丙酮可有利于疾病预防和提高运动成绩。 相似文献
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Jeukendrup AE 《Journal of sports sciences》2011,29(Z1):S91-S99
Endurance sports are increasing in popularity and athletes at all levels are looking for ways to optimize their performance by training and nutrition. For endurance exercise lasting 30 min or more, the most likely contributors to fatigue are dehydration and carbohydrate depletion, whereas gastrointestinal problems, hyperthermia, and hyponatraemia can reduce endurance exercise performance and are potentially health threatening, especially in longer events (>4 h). Although high muscle glycogen concentrations at the start may be beneficial for endurance exercise, this does not necessarily have to be achieved by the traditional supercompensation protocol. An individualized nutritional strategy can be developed that aims to deliver carbohydrate to the working muscle at a rate that is dependent on the absolute exercise intensity as well as the duration of the event. Endurance athletes should attempt to minimize dehydration and limit body mass losses through sweating to 2-3% of body mass. Gastrointestinal problems occur frequently, especially in long-distance races. Problems seem to be highly individual and perhaps genetically determined but may also be related to the intake of highly concentrated carbohydrate solutions, hyperosmotic drinks, as well as the intake of fibre, fat, and protein. Hyponatraemia has occasionally been reported, especially among slower competitors with very high intakes of water or other low sodium drinks. Here I provide a comprehensive overview of recent research findings and suggest several new guidelines for the endurance athlete on the basis of this. These guidelines are more detailed and allow a more individualized approach. 相似文献
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The aim of this study was to determine the variations in substrate utilization between men and women matched for ventilatory threshold (Tvent) during incremental arm cranking and leg cycling exercise at 70, 85, 100 and 115% of the mode-specific Tvent. Recreationally active men (n=12) and women (n=10) with similar values for percentage of peak oxygen consumption at Tvent participated in the study. Ventilatory equivalence, excess CO2 and modified V-slope methods were used concurrently to determine Tvent. The participants performed 5 min of exercise at each of 70, 85, 100 and 115% Tvent during both arm cranking and leg cycling exercise. The females were tested during the early follicular phase for all trials. A two-way mixed-design analysis of variance was performed to test for differences between the sexes. When carbohydrate and fat oxidation were expressed relative to total fat-free mass, carbohydrate oxidation during arm cranking and leg cycling was significantly higher in men than women at each percentage of Tvent. In contrast, women showed significantly higher fat oxidation across intensities during both arm cranking and leg cycling. Our results suggest that when substrate utilization is expressed relative to total fat-free mass, women appear to maintain a higher rate of fat and lower rate of carbohydrate oxidation than men during both incremental arm cranking and leg cycling exercise relative to Tvent. 相似文献
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AbstractA key element contributing to deteriorating exercise capacity during physically demanding sport appears to be reduced carbohydrate availability coupled with an inability to effectively utilize alternative lipid fuel sources. Paradoxically, cognitive and physical decline associated with glycogen depletion occurs in the presence of an over-abundance of fuel stored as body fat that the athlete is apparently unable to access effectively. Current fuelling tactics that emphasize high-carbohydrate intakes before and during exercise inhibit fat utilization. The most efficient approach to accelerate the body’s ability to oxidize fat is to lower dietary carbohydrate intake to a level that results in nutritional ketosis (i.e., circulating ketone levels >0.5 mmol/L) while increasing fat intake for a period of several weeks. The coordinated set of metabolic adaptations that ensures proper interorgan fuel supply in the face of low-carbohydrate availability is referred to as keto-adaptation. Beyond simply providing a stable source of fuel for the brain, the major circulating ketone body, beta-hydroxybutyrate, has recently been shown to act as a signalling molecule capable of altering gene expression, eliciting complementary effects of keto-adaptation that could extend human physical and mental performance beyond current expectation. In this paper, we review these new findings and propose that the shift to fatty acids and ketones as primary fuels when dietary carbohydrate is restricted could be of benefit for some athletes. 相似文献
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Energy balance and body composition in sports and exercise 总被引：2，自引：0，他引：2
Loucks AB 《Journal of sports sciences》2004,22(1):1-14
Many athletes, especially female athletes and participants in endurance and aesthetic sports and sports with weight classes, are chronically energy deficient. This energy deficiency impairs performance, growth and health. Reproductive disorders in female athletes are caused by low energy availability (defined as dietary energy intake minus exercise energy expenditure), perhaps specifically by low carbohydrate availability, and not by the stress of exercise. These reproductive disorders can be prevented or reversed by dietary supplementation in compensation for exercise energy expenditure without any moderation of the exercise regimen. Energy balance is not the objective of athletic training. To maximize performance, athletes strive to achieve an optimum sport-specific body size, body composition and mix of energy stores. To pursue these objectives, athletes need to manage fat, protein and carbohydrate balances separately, but it is impractical for athletes to monitor these balances directly, and appetite is not a reliable indicator of their energy and macronutrient needs. To guide their progress, athletes need to eat by discipline and to monitor specific, reliable and practical biomarkers of their objectives. Skinfolds and urinary ketones may be the best biomarkers of fat stores and carbohydrate deficiency, respectively. Research is needed to identify and validate these and other markers. 相似文献
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Sareena Hamzah Siobhan Higgins Tamara Abraham Paul Taylor Daiva Vizbaraite 《Journal of sports sciences》2013,31(14):1545-1554
Abstract The aim of this study was to determine whether rates of total fat and carbohydrate oxidation and endurance capacity during running conducted in the fasted state are influenced by the glycaemic index (GI) of high carbohydrate diets consumed over 5 days. Nine healthy males performed three treadmill runs to exhaustion at 65% of maximum oxygen uptake ([Vdot]O2max): after a habitual diet (control trial), after 5 days on a high carbohydrate/high glycaemic index diet, and after 5 days on a high carbohydrate/low glycaemic index diet in randomized counterbalanced order. No significant differences in rates of fat and carbohydrate oxidation, concentrations of plasma insulin, glucose, non-esterified fatty acids and glycerol, or time to exhaustion were observed between the high carbohydrate/high glycaemic index and high carbohydrate/low glycaemic index trials. Compared with the control trial, the concentration of plasma glycerol and rate of fat oxidation were lower (P < 0.05) and the rate of carbohydrate oxidation higher (P < 0.05) in both the high carbohydrate/high glycaemic index diet and high carbohydrate/low glycaemic index trials during the run to exhaustion. In conclusion, the extent by which a high carbohydrate diet consumed over 5 days reduces rate of fat oxidation during subsequent running exercise in the fasted state is not influenced by the glycaemic index of the diet. 相似文献
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Ceri W. Nicholas Clyde Williams Henryk K.A. Lakomy Gary Phillips Andrea Nowitz 《Journal of sports sciences》2013,31(4):283-290
The aim of this study was to examine the effects of ingesting a carbohydrate‐electrolyte solution on endurance capacity during a prolonged intermittent, high‐intensity shuttle running test (PIHSRT). Nine trained male games players performed two exercise trials, 7 days apart. On each occasion, they completed 75 min exercise, comprising of five 15‐min periods of intermittent running, consisting of sprinting, interspersed with periods of jogging and walking (Part A), followed by intermittent running to fatigue (Part B). The subjects were randomly allocated either a 6.9% carbohydrate‐electrolyte solution (CHO) or a non‐carbohydrate placebo (CON) immediately prior to exercise (5 ml kg‐1 body mass) and every 15 min thereafter (2 ml kg‐1 body mass). Venous blood samples were obtained at rest, during and after each PIHSRT for the determination of glucose, lactate, plasma free fatty acid, glycerol, ammonia, and serum insulin and electrolyte concentrations. During Part B, the subjects were able to continue running longer when fed CHO (CHO = 8.9 ± 1.5 min vs CON = 6.7 ± 1.0 min; P < 0.05) (mean ± s.e.m.). These results show that drinking a carbohydrate‐electrolyte solution improves endurance running capacity during prolonged intermittent exercise. 相似文献
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《European Journal of Sport Science》2013,13(2):79-87
Abstract In this study we determined the exercise intensity that elicits the highest fat oxidation rate in 15 obese women and 13 obese men. Furthermore the relationship between this intensity with the lactate (LT) and ventilatory thresholds (VT) was investigated in order to give training recommendation for maximal fat utilization during endurance exercise. After an incremental exercise test until exhaustion on a cycle ergometer, subjects performed six 20-min exercise bouts of 25, 35, 45, 55, 65 and 75% VO2peak. The 20 min stages were randomly assigned and spread over two separate occasions (three bouts per occasion). Substrate oxidation was measured with indirect calorimetry and was calculated using stochiometric equations. In both, women and men the highest fat oxidation rate occurred at 65% VO2peak and this did not coincide with either the VT or LT. A significant correlation between VT and LT could not be found in women (r=0.33) nor men (r=0.277). In obese women and men training recommendation for maximal fat utilization should not only be given by the intensity at which AnT occurs. 相似文献