共查询到19条相似文献，搜索用时 203 毫秒
1.
补充糖对运动员训练和竞技能力的影响 总被引：1，自引：0，他引：1
运动员饮食中含糖低于“最适宜的”量易诱发过早疲劳。在进行长时间运动时疲劳常因肌糖元排空,其含量低于临界值(50mM/kg湿肌)或血糖浓度降至临界值(3.3mM/L)以下引起,这时运动强度必将显著降低甚或被中止。因此,摄食高糖饮食可增加肌糖元及改善耐力,维持高的训练质量。摄食糖的数量、糖的类型和摄取时间三者都是改善运动后恢复速率的营养策略的组成部分。 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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在长时间运动中,血糖和肌糖元是运动肌肉利用的二种主要碳水化合物,肌糖元浓度是决定耐力性运动能力的主要因素。在长时间运动中,增加摄取碳水化合物使可利用的糖类增加,可以推迟疲劳的出现,增加耐力能力。但摄取糖类(CHO)食物对运动中肌糖元利用的影响尚很少研究,且以往的研究都是摄取液体饮料,本实验是研究摄取固体糖类食品对4小时自行车运动中肌糖元利用的影响。实验方法: 十名男性受试者的身体特征见表一表一:受试者身休特征(N=10) 相似文献
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糖是人体最主要的热源物质,是人体从事体育活动的物质基础。我们知道,人体在进行运动时,肌肉工作能力增强,肌肉此时的摄糖量可为安静时的20倍以上。运动使体内的糖元大量消耗,如果运动前体内糖元储备量木足,会使机体耐久力下降,运动时间缩短。运动医学研究证明,经常参加体育活动的人,体内的肌糖元储存量比不参加运动的人高得多,肌肉工作的潜力也大得多。在同样的运动负荷时,不参加运动的人肌糖元减少得更为显著。人体体内储备的糖主要以三种形式存在,一种是血糖,一种是肌糖元,另一种是肝糖元。一般人体内储糖量为32O克左右,… 相似文献
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本文对八名健康的男性进行运动前果糖、葡萄糖摄入和运动中肌糖元利用率的比较研究。受试者完成三个随机拟定的试验,每个试验包括以75%最大吸氧量做30分钟自行车练习。每次试验开始前45分钟,受试者口服50克葡萄糖,或50克果糖,或50克人工合成甜料。试验中吸氧量和呼吸商无差异。葡萄糖的摄入使血糖升高(P<0.05)。随着训练的进行,葡萄糖组的血糖迅速下降,运动到20分钟时,达到每升3.18±0.15(SE)毫克分子的最低点。这个值低于果糖试验组(3.79±0.20)和合成甜糖试验组(3.99±0.18)的相应值。果糖组和合成甜料组在运动中血糖水平没有差异。肌糖元的利用率,葡萄糖组(55.4±3.3毫克分子/公斤体重)大于合成甜料组(42.8±4.2)(P<0.05),但果糖组和合成甜料组没有这种差别(P=0.07)。肌糖元的利用率存在一种倾向,即果糖组低于葡萄糖组。总之这些结果表明运动前摄入葡萄糖的效果是不利的,通常果糖组和合成甜料组则没有这种情况。 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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一前言激烈的运动中腿部肌肉的肌糖元的量急剧减少。特别是用自行车测功器进行到力竭时肌糖元几乎消失。因此肌糖元已被视为肌肉持续运动的重要因素,但是也有的认为在激烈的长跑比赛后腿部肌肉的肌糖元并不是完全消失。还有,连续运动三天虽然肌糖顺次下降但并未见完全消失。因而在长跑至力竭之后,由于在肌肉中还残余有肌糖元,其与长跑能力之间的关系不是直接的、简单的,而是相当复杂的。按近年Gollnick等用自行车测功器进行运 相似文献
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Carbohydrates and fat for training and recovery 总被引：3，自引：0，他引：3
An important goal of the athlete's everyday diet is to provide the muscle with substrates to fuel the training programme that will achieve optimal adaptation for performance enhancements. In reviewing the scientific literature on post-exercise glycogen storage since 1991, the following guidelines for the training diet are proposed. Athletes should aim to achieve carbohydrate intakes to meet the fuel requirements of their training programme and to optimize restoration of muscle glycogen stores between workouts. General recommendations can be provided, preferably in terms of grams of carbohydrate per kilogram of the athlete's body mass, but should be fine-tuned with individual consideration of total energy needs, specific training needs and feedback from training performance. It is valuable to choose nutrient-rich carbohydrate foods and to add other foods to recovery meals and snacks to provide a good source of protein and other nutrients. These nutrients may assist in other recovery processes and, in the case of protein, may promote additional glycogen recovery when carbohydrate intake is suboptimal or when frequent snacking is not possible. When the period between exercise sessions is < 8 h, the athlete should begin carbohydrate intake as soon as practical after the first workout to maximize the effective recovery time between sessions. There may be some advantages in meeting carbohydrate intake targets as a series of snacks during the early recovery phase, but during longer recovery periods (24 h) the athlete should organize the pattern and timing of carbohydrate-rich meals and snacks according to what is practical and comfortable for their individual situation. Carbohydrate-rich foods with a moderate to high glycaemic index provide a readily available source of carbohydrate for muscle glycogen synthesis, and should be the major carbohydrate choices in recovery meals. Although there is new interest in the recovery of intramuscular triglyceride stores between training sessions, there is no evidence that diets which are high in fat and restricted in carbohydrate enhance training. 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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An important goal of the athlete's everyday diet is to provide the muscle with substrates to fuel the training programme that will achieve optimal adaptation for performance enhancements. In reviewing the scientific literature on post-exercise glycogen storage since 1991, the following guidelines for the training diet are proposed. Athletes should aim to achieve carbohydrate intakes to meet the fuel requirements of their training programme and to optimize restoration of muscle glycogen stores between workouts. General recommendations can be provided, preferably in terms of grams of carbohydrate per kilogram of the athlete's body mass, but should be fine-tuned with individual consideration of total energy needs, specific training needs and feedback from training performance. It is valuable to choose nutrient-rich carbohydrate foods and to add other foods to recovery meals and snacks to provide a good source of protein and other nutrients. These nutrients may assist in other recovery processes and, in the case of protein, may promote additional glycogen recovery when carbohydrate intake is suboptimal or when frequent snacking is not possible. When the period between exercise sessions is <8?h, the athlete should begin carbohydrate intake as soon as practical after the first workout to maximize the effective recovery time between sessions. There may be some advantages in meeting carbohydrate intake targets as a series of snacks during the early recovery phase, but during longer recovery periods (24?h) the athlete should organize the pattern and timing of carbohydrate-rich meals and snacks according to what is practical and comfortable for their individual situation. Carbohydrate-rich foods with a moderate to high glycaemic index provide a readily available source of carbohydrate for muscle glycogen synthesis, and should be the major carbohydrate choices in recovery meals. Although there is new interest in the recovery of intramuscular triglyceride stores between training sessions, there is no evidence that diets which are high in fat and restricted in carbohydrate enhance training. 相似文献
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Stellingwerff T Boit MK Res PT;International Association of Athletics Federations 《Journal of sports sciences》2007,25(Z1):S17-S28
Middle-distance athletes implement a dynamic continuum in training volume, duration, and intensity that utilizes all energy-producing pathways and muscle fibre types. At the centre of this periodized training regimen should be a periodized nutritional approach that takes into account acute and seasonal nutritional needs induced by specific training and competition loads. The majority of a middle-distance athlete's training and racing is dependant upon carbohydrate-derived energy provision. Thus, to support this training and racing intensity, a high carbohydrate intake should be targeted. The required energy expenditure throughout each training phase varies significantly, and thus the total energy intake should also vary accordingly to better maintain an ideal body composition. Optimizing acute recovery is highly dependant upon the immediate consumption of carbohydrate to maximize glycogen resynthesis rates. To optimize longer-term recovery, protein in conjunction with carbohydrate should be consumed. Supplementation of beta-alanine or sodium bicarbonate has been shown to augment intra- and extracellular buffering capacities, which may lead to a small performance increase. Future studies should aim to alter specific exercise (resistance vs. endurance) and/or nutrition stimuli and measure downstream effects at multiple levels that include gene and molecular signalling pathways, leading to muscle protein synthesis, that result in optimized phenotypic adaptation and performance. 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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An athlete's carbohydrate intake can be judged by whether total daily intake and the timing of consumption in relation to exercise maintain adequate carbohydrate substrate for the muscle and central nervous system ("high carbohydrate availability") or whether carbohydrate fuel sources are limiting for the daily exercise programme ("low carbohydrate availability"). Carbohydrate availability is increased by consuming carbohydrate in the hours or days prior to the session, intake during exercise, and refuelling during recovery between sessions. This is important for the competition setting or for high-intensity training where optimal performance is desired. Carbohydrate intake during exercise should be scaled according to the characteristics of the event. During sustained high-intensity sports lasting ~1 h, small amounts of carbohydrate, including even mouth-rinsing, enhance performance via central nervous system effects. While 30-60 g · h(-1) is an appropriate target for sports of longer duration, events >2.5 h may benefit from higher intakes of up to 90 g · h(-1). Products containing special blends of different carbohydrates may maximize absorption of carbohydrate at such high rates. In real life, athletes undertake training sessions with varying carbohydrate availability. Whether implementing additional "train-low" strategies to increase the training adaptation leads to enhanced performance in well-trained individuals is unclear. 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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《European Journal of Sport Science》2013,13(2):191-199
Abstract The increased energy demand that occurs with incremental exercise intensity is met by increases in the oxidation of both endogenous fat and carbohydrate stores up to an intensity of ~70% V˙O2max in trained individuals. However, when exercise intensity increases beyond this workload, fat oxidation rates decline, both from a relative and absolute perspective. As endogenous glycogen use is accelerated, glycogen stores can become depleted, ultimately resulting in fatigue and the inability to maintain high intensity, submaximal exercise (>70% V˙O2max). Despite a considerable accumulation of knowledge that has been gained over the past half century, the precise mechanism(s) regulating muscle fuel selection and underpinning the aforementioned decline in fat oxidation remain largely unclear. A greater understanding would undoubtedly lead to novel strategies to increase fat utilization and, as such, improve exercise capacity. The present review primarily addresses one of the most prominent theories to explain the phenomenon of diminished fat oxidation during high intensity, submaximal exercise; a reduced availability of muscle free carnitine for mitochondrial fat translocation. This is discussed in the light of recent work in this area taking advantage of the discovery that muscle carnitine content can be increased in vivo in humans. Furthermore, the evidence supporting the recently proposed theory that reduced muscle co-enzyme A availability to several key enzymes in the fat oxidation pathway may also exert a degree of control over muscle fuel selection during exercise is also considered. Strong correlational evidence exists that muscle free carnitine availability is likely to be a key limiting factor to fat oxidation during high intensity, submaximal exercise. However, it is concluded that further intervention studies manipulating the muscle carnitine pool in humans are required to establish a direct causal role. In addition, it is concluded that while a depletion of muscle coenzyme A availability during exercise also offers a viable mechanism for impairing fat oxidation, at present, this remains speculative. 相似文献
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《European Journal of Sport Science》2013,13(1):3-14
Abstract Both carbohydrate depletion and dehydration have been shown to decrease performance whilst severe dehydration can also cause adverse health effects. Therefore carbohydrate and fluid requirements are increased with exercise. Ingestion of 200–300?g of CHO 3–4?h prior to exercise is an effective strategy in order to meet daily CHO demands and increase CHO availability during the subsequent exercise period. There is little evidence that CHO during the hour immediately prior to exercise has adverse effects such as rebound hypoglycaemia. CHO ingestion during exercise has been shown to improve performance as measured by enhanced work output or decreased exercise time to complete a fixed amount of work. Recent studies have demonstrated that exogenous CHO oxidation rates can be increased by ingesting combinations of CHO that use different intestinal CHO transporters. After exercise maximal muscle glycogen re-synthesis rates can be achieved by ingesting CHO at a rate of ～1.2?g/kg/h, in relatively frequent (e.g., 15–30?min) intervals for up to 5?h following exercise. Protein amino acid mixtures may increase glycogen synthesis further but only if relatively small amounts of CHO are ingested. Hypohydration and hyperthermia alone have negative effects on performance but their combination is particularly serious, both in terms of performance and health. Dehydration can be prevented by fluid ingestion pre exercise and during exercise. Because of large individual differences it is difficult to individualise the advice. Perhaps the best guidance for athletes is to weigh themselves to assess fluid losses during training and racing and limit weight losses to 1% during exercise lasting longer than 1.5?h. Excessive fluid intake has been associated with hyponatremia. Post exercise the volume of fluid ingested and sodium intake are important determinants of rehydration. 相似文献