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1.
Energy balance and body composition in sports and exercise   总被引：2，自引：0，他引：2  
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   

2.
Throwers, jumpers, and combined events athletes require speed, strength, power, and a wide variety of technical skills to be successful in their events. Only a handful of studies have assessed the nutritional needs of such athletes. Because of this, recommendations for nutritional requirements to support and enhance training and competition performances for these athletes are made using research findings from sports and exercise protocols similar to their training and competitive events. The goals of the preparation cycle of nutrition periodization for these athletes include attaining desirable body weight, a high ratio of lean body mass to body height, and improving muscular power. Nutritional recommendations for training and competition periods include: (1) meeting energy needs; (2) timing consumption of adequate fluid and electrolyte intakes before, during, and after exercise to promote adequate hydration; (3) timing consumption of carbohydrate intake to provide adequate fuel for energy demands and to spare protein for muscle repair, growth, and maintenance; (4) timing consumption of adequate protein intake to meet protein synthesis and turnover needs; and (5) consuming effective nutritional and dietary supplements. Translating these nutrient and dietary recommendations into guidelines these athletes can apply during training and competition is important for enhancing performance.  相似文献   

3.
Abstract

The oral–pharyngeal cavity and the gastrointestinal tract are richly endowed with receptors that respond to taste, temperature and to a wide range of specific nutrient and non-nutritive food components. Ingestion of carbohydrate-containing drinks has been shown to enhance endurance exercise performance, and these responses have been attributed to post-absorptive effects. It is increasingly recognised, though, that the response to ingested carbohydrate begins in the mouth via specific carbohydrate receptors and continues in the gut via the release of a range of hormones that influence substrate metabolism. Cold drinks can also enhance performance, especially in conditions of thermal stress, and part of the mechanism underlying this effect may be the response to cold fluids in the mouth. There is also some, albeit not entirely consistent, evidence for effects of caffeine, quinine, menthol and acetic acid on performance or other relevant effects. This review summarises current knowledge of responses to mouth sensing of temperature, carbohydrate and other food components, with the goal of assisting athletes to implement practical strategies that make best use of its effects. It also examines the evidence that oral intake of other nutrients or characteristics associated with food/fluid intake during exercise can enhance performance via communication between the mouth/gut and the brain.  相似文献   

4.
Strength and power athletes are primarily interested in enhancing power relative to body weight and thus almost all undertake some form of resistance training. While athletes may periodically attempt to promote skeletal muscle hypertrophy, key nutritional issues are broader than those pertinent to hypertrophy and include an appreciation of the sports supplement industry, the strategic timing of nutrient intake to maximize fuelling and recovery objectives, plus achievement of pre-competition body mass requirements. Total energy and macronutrient intakes of strength-power athletes are generally high but intakes tend to be unremarkable when expressed relative to body mass. Greater insight into optimization of dietary intake to achieve nutrition-related goals would be achieved from assessment of nutrient distribution over the day, especially intake before, during, and after exercise. This information is not readily available on strength-power athletes and research is warranted. There is a general void of scientific investigation relating specifically to this unique group of athletes. Until this is resolved, sports nutrition recommendations for strength-power athletes should be directed at the individual athlete, focusing on their specific nutrition-related goals, with an emphasis on the nutritional support of training.  相似文献   

5.
目的:研究耐力训练对大鼠FTO基因表达的影响以及与摄食量的关系。方法:以SD大鼠为研究对象,将大鼠分为对照组(C组)和运动训练组(E组),以12周无负重游泳为运动手段,测定肝脏、骨骼肌、脂肪组织和下丘脑组织中FTO基因mRNA表达、大鼠体重、肾周与附睾周围脂肪重量及脂肪重量与体重百分比、大鼠每天摄食量。结果:FTO基因mRAN在骨骼肌、脂肪组织和下丘脑中表达均显著高于肝脏组织,下丘脑显著高于骨骼肌和脂肪组织,脂肪组织与骨骼肌未见显著性差异,耐力训练对肝脏、骨骼肌和脂肪组织中FTO基因mRNA表达未见显著性影响,而脑组织表达显著升高;大鼠体重在不同的对应时间点,运动训练组与对照组未见显著性差异;大鼠摄食量在不同对应时间点,运动训练组显著高于对照组;肾周及附睾周围脂肪组织重量及脂肪重与体重百分比运动训练组显著低于对照组。结论:耐力训练可以提高下丘脑中FTO基因表达,从而刺激大鼠提高摄食量,而运动能量的消耗抵消了因摄食增加引起的体重增加。  相似文献   

6.
Fluid and fuel intake during exercise   总被引：10，自引：1，他引：9  
The amounts of water, carbohydrate and salt that athletes are advised to ingest during exercise are based upon their effectiveness in attenuating both fatigue as well as illness due to hyperthermia, dehydration or hyperhydration. When possible, fluid should be ingested at rates that most closely match sweating rate. When that is not possible or practical or sufficiently ergogenic, some athletes might tolerate body water losses amounting to 2% of body weight without significant risk to physical well-being or performance when the environment is cold (e.g. 5-10 degrees C) or temperate (e.g. 21-22 degrees C). However, when exercising in a hot environment ( > 30 degrees C), dehydration by 2% of body weight impairs absolute power production and predisposes individuals to heat injury. Fluid should not be ingested at rates in excess of sweating rate and thus body water and weight should not increase during exercise. Fatigue can be reduced by adding carbohydrate to the fluids consumed so that 30-60 g of rapidly absorbed carbohydrate are ingested throughout each hour of an athletic event. Furthermore, sodium should be included in fluids consumed during exercise lasting longer than 2 h or by individuals during any event that stimulates heavy sodium loss (more than 3-4 g of sodium). Athletes do not benefit by ingesting glycerol, amino acids or alleged precursors of neurotransmitter. Ingestion of other substances during exercise, with the possible exception of caffeine, is discouraged. Athletes will benefit the most by tailoring their individual needs for water, carbohydrate and salt to the specific challenges of their sport, especially considering the environment's impact on sweating and heat stress.  相似文献   

7.
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   

8.
Abstract

Amino acids contribute between 2–8% of the energy needs during endurance exercise. Endurance exercise training leads to an adaptive reduction in the oxidation of amino acids at the same absolute exercise intensity, however, the capacity to oxidize amino acids goes up due to the increase in the total amount of the rate limiting enzyme, branched chain 2-oxo-acid dehydrogenase. There appears to be a modest increase (range?=?12–95%) in protein requirements only for very well trained athletes who are actively training. Although the majority of athletes will have ample dietary protein to meet any increased need, those on a hypoenergetic diet or during extreme periods of physical stress may need dietary manipulation to accommodate the need. Caffeine is a trimethylxanthine derivative that is common in many foods and beverages. The consumption of caffeine (3–7 mg/kg) prior to endurance exercise improves performance for habitual and non-habitual consumers. The ergogenic effect is likely due to a direct effect on muscle contractility and not via an enhancement of fatty acid oxidation. Creatine is important in intra-cellular energy shuttling and in cellular fluid regulation. Creatine monohydrate supplementation (20 g/d X 3–5 days) increases fat-free mass, improves muscle strength during repetitive high intensity contractions and increases fat-free mass accumulation and strength during a period of weight training. Given the increase in weight, there are likely neutral or even performance reducing effects in sports that are influenced by body mass (i.e., running, hill climbing cycling).  相似文献   

9.
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   

10.
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   

11.
补充糖对运动员训练和竞技能力的影响   总被引：8，自引：0，他引：8  
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   

12.
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   

13.
The primary roles for nutrition in sprints are for recovery from training and competition and influencing training adaptations. Sprint success is determined largely by the power-to-mass ratio, so sprinters aim to increase muscle mass and power. However, extra mass that does not increase power may be detrimental. Energy and protein intake are important for increasing muscle mass. If energy balance is maintained, increased mass and strength are possible on a wide range of protein intakes, so energy intake is crucial. Most sprinters likely consume ample protein. The quantity of energy and protein intake necessary for optimal training adaptations depends on the individual athlete and training demands; specific recommendations for all sprinters are, at best, useless, and are potentially harmful. However, if carbohydrate and fat intake are sufficient to maintain energy levels, then increased protein intake is unlikely to be detrimental. The type and timing of protein intake and nutrients ingested concurrently must be considered when designing optimal nutritional strategies for increasing muscle mass and power. On race day, athletes should avoid foods that result in gastrointestinal discomfort, dehydration or sluggishness. Several supplements potentially influence sprint training or performance. Beta-alanine and bicarbonate may be useful as buffering agents in longer sprints. Creatine may be efficacious for increasing muscle mass and strength and perhaps increasing intensity of repeat sprint performance during training.  相似文献   

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   

15.
Ramadan fasting, involving abstinence from fluid and food from sunrise to sundown, results in prolonged periods without nutrient intake and inflexibility with the timing of eating and drinking over the day. Dietary choices may also change due to special eating rituals. Although nutrition guidelines are specific to the sport, to the periodized training and competition calendar, and to the individual, many promote the consumption of carbohydrate and fluid before and during exercise, and consumption of protein, carbohydrate, and fluids soon after the session is completed. Failing to meet overall nutritional needs, or to provide specific nutritional support to a session of exercise, is likely to impair acute performance and reduce the effectiveness of training or recovery. Muslim athletes who fast during Ramadan should use overnight opportunities to consume foods and drinks that can supply the nutrients needed to promote performance, adaptation, and recovery in their sports. Because of the benefits of being able to consume at least some of these nutrients before, during or after an exercise session, the schedule of exercise should be shifted where possible to the beginning or end of the day, or during the evening when some nutritional support can be provided.  相似文献   

16.
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   

17.
耐力运动员较少进行力量训练,主要担心肌肉肥大对毛细血管和线粒体功能产生潜在负性的影响。但是肌肉的无氧工作能力、肌肉力量和肌肉的爆发力可能影响耐力运动项目的成绩。力量训练能够提高神经肌肉特征和无氧代谢能力。耐力训练中嵌入力量训练的训练模式可能有助于提高耐力性项目成绩。  相似文献   

18.
采用文献资料法等分析饮料在体育运动中抗疲劳功效及价值。主要结论:功能性饮料能够短时高效的补充能量和抗疲劳,滥用会引起心血管系统异常。茶饮可通过胶原蛋白合成加速运动损伤中组织创口愈合,茶饮中咖啡碱可引起中枢神经兴奋、增大肌肉张力、消除疲劳。鲜榨果蔬饮料能及时补充运动后人体所需各种微量元素,促进胃肠道蠕动,具有改善疲劳抗氧化等功效。矿物质饮料提供运动时人体所需矿物质元素,改善运动时人体内环境平衡,具有镇痛抗氧化、提高免疫力及增强身体素质,消除疲劳等作用。运动后饮用碳酸饮料会引发腹胀,易于出现注意力不集中、心悸、疲乏等困意感,存在引发骨质酥松症,增加运动中骨折的风险。含有乳清蛋白的乳饮料有助于提高机体能量,帮助重建受损的肌纤维,可延缓中枢神经系统疲劳,更好地提升运动耐力和运动表现。  相似文献   

19.
Abstract

The synergistic stimulating effect of combined intake of carbohydrate and protein on plasma insulin concentration has been reported previously. However, it remains unclear whether the amount of protein ingested after exercise affects the concentrations of plasma insulin and amino acids. This study of trained men compared the effects of post-exercise co-ingestion of carbohydrate plus different amounts of whey protein hydrolysates (WPHs) with carbohydrate alone on (1) blood biochemical parameters of carbohydrate metabolism during the post-exercise phase, and (2) endurance performance. Eight trained men exercised continuously for 70 min. Immediately after exercise and 30, 60, 90, and 120 min later, the participants received supplements containing: (1) 17.5 g carbohydrate, (2) 3.0 g WPHs and 17.5 g carbohydrate (L-WPH), or (3) 8.0 g WPHs and 17.5 g carbohydrate (H-WPH). After a 2-h recovery period, the participants performed an endurance performance test. The concentrations of blood glucose were lower and plasma insulin significantly higher in the H-WPH trial compared with the carbohydrate trial. The concentrations of plasma amino acids were increased in a dose-dependent manner following ingestion of different amounts of WPHs with carbohydrate. Endurance performance was not significantly different between the three trials. Co-ingestion of carbohydrate and H-WPH was more effective than ingestion of carbohydrate alone for stimulating insulin secretion and increasing the availability of plasma amino acids. These results suggest that plasma concentrations of amino acids during the recovery period are determined by the amount of dietary protein ingested, and that it is necessary to increase the concentration of plasma amino acids above a certain level to stimulate insulin secretion.  相似文献   

20.
Contemporary training for power sports involves diverse routines that place a wide array of physiological demands on the athlete. This requires a multi-faceted nutritional strategy to support both general training needs--tailored to specific training phases--as well as the acute demands of competition. Elite power sport athletes have high training intensities and volumes for most of the training season, so energy intake must be sufficient to support recovery and adaptation. Low pre-exercise muscle glycogen reduces high-intensity performance, so daily carbohydrate intake must be emphasized throughout training and competition phases. There is strong evidence to suggest that the timing, type, and amount of protein intake influence post-exercise recovery and adaptation. Most power sports feature demanding competition schedules, which require aggressive nutritional recovery strategies to optimize muscle glycogen resynthesis. Various power sports have different optimum body compositions and body weight requirements, but increasing the power-to-weight ratio during the championship season can lead to significant performance benefits for most athletes. Both intra- and extracellular buffering agents may enhance performance, but more research is needed to examine the potential long-term impact of buffering agents on training adaptation. Interactions between training, desired physiological adaptations, competition, and nutrition require an individual approach and should be continuously adjusted and adapted.  相似文献   

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