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1.
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
2.
Early metabolism evaluation making traditional Chinese medicine effective and safe therapeutics 总被引：1，自引：0，他引：1
Increasing attention is being paid to the scientific evaluation of traditional Chinese medicine （TCM）. As many TCMs are capable of biotransformation in the gastrointestinal tract, attention to biotransforrnation of TCM in the gastrointestinal tract may lead to discovery of the active components and active mechanisms. In this article, we review reports that host metabolic enzymes and intestinal bacteria may be responsible for the metabolism of TCM. Good understanding of the in vivo course of TCM will help us to know how to conduct metabolism evaluation of TCM by using in vitro human-derived system. This evaluation system will create new views on TCM as effective and safe therapeutic agents. 相似文献
3.
《运动与健康科学(英文)》2014,3(3):217-224
BackgroundThe aim of this study was to compare 6 weeks short-term moderate intensity aerobic exercise and dieting on serum metabolomics and cardio-metabolic risk factors in pre-menopausal women.MethodsNinety previously inactive overweight and obese (BMI 25–35 kg/m2) women (age 41.5 ± 7.6 years) were randomized to either a 6-week Nordic walking exercise program (EX, n = 45) or dietary counseling group (DI, n = 45). Body composition, serum glucose, insulin and lipids were measured. Serum low-molecular-weight metabolites and lipid constituents were analyzed by nuclear magnetic resonance spectroscopy. Measurements were done at baseline and 7 days after the last training session.ResultsSix weeks aerobic exercise program yielded reductions in serum free fatty acids (−34.7%, 95% confidence interval (CI), −50 to −18, p < 0.001), glucose (−9.6%, 95%CI, −15 to −4, p < 0.001) and homeostasis model assessment of insulin resistance (HOMA-IR) (−28.7%, 95%CI, −48 to −10, p = 0.005) without changes in body weight or fat mass. Diet counseling resulted in loss of body weight (1.5%, 95%CI, −2.3 to −0.7, p = 0.001) but no changes in free fatty acids, fasting glucose, or HOMA-IR were found.ConclusionOur results indicate that small weight loss does not produce measurable health benefits, whereas short-term regular aerobic exercise can improve glucose and lipid metabolism even in the absence of weight loss in previously sedentary overweight and obese women. 相似文献
4.
孙小华 《武汉体育学院学报》1996,(4)
三个供能系统不是独立存在的个体，而是相互作用，相互依存的整体。整体水平的供能方式不能代表某一局部的能量代谢情况，两者之间存在很大的差异。恢复过程不是简单的能源物质的补充，更重要的是蛋白质的合成。作者对皮艇训练中的能量代谢和运动后的恢复过程进行了讨论，并提出了皮艇训练的四项生理学原则。 相似文献
5.
对“12min跑“取代1000m跑提高健身效果的研究 总被引：1，自引：0，他引：1
通过对“12min跑“的生理学分析,确定其是测定有氧代谢能力的项目之一.在大学体育教学内容改革之际,在课中设置“12min跑“的素质内容练习,并用其来取代“1 000m跑“测验,对提高大学生有氧代谢能力,获得良好健身效果,起到了非常重要的作用. 相似文献
6.
Ryan S. Sacko Kerry McIver Ali Brian David F. Stodden 《Journal of sports sciences》2018,36(21):2412-2418
This study examined the metabolic cost (METs) of performing object projection skills at three practice trial intervals (6, 12, and 30 seconds). Forty adults (female n = 20) aged 18–30 (M = 23.7 ± 2.9 years) completed three, nine-minute sessions of skill trials performed at 6, 12, and 30 second intervals. Participants performed kicking, throwing and striking trials in a blocked schedule with maximal effort. Average METs during each session were measured using a COSMED K4b2. A three (interval condition) X two (sex) ANOVA was conducted to examine differences in METs across interval conditions and by sex. Results indicated a main effect for interval condition (F(5,114) = 187.02, p < .001, η2 = 0.76) with decreased interval times yielding significantly higher METs [30 sec = 3.45, 12 sec = 5.68, 6 sec = 8.21]. A main effect for sex (F(5, 114) = 35.39, p < .001, η2 = 0.24) also was found with men demonstrating higher METs across all intervals. At a rate of only two trials/min, participants elicited moderate physical activity, with 12 and 6-second intervals exhibiting vigorous PA. Demonstrating MVPA during the performance of object projection skill performance has potential implications for PA interventions. 相似文献
7.
The development of fatigue during exercise and the subsequent onset of exhaustion occur earlier in the heat than in cooler environments. The underlying mechanisms responsible for the premature development of fatigue in the heat have yet to be clearly identified. However, the proposed mechanisms include metabolic, cardiovascular and central nervous system perturbations, together with an elevated core temperature. Fluid ingestion is one of three strategies that have been shown to be successful in enhancing the performance of endurance exercise in the heat, with the other interventions being precooling and acclimatization. However, like the development of fatigue in the heat, the mechanisms by which fluid ingestion allows for improved exercise performance remain unclear. We propose that fluid ingestion enhances exercise performance in the heat by increasing the heat storage capacity of the body. We suggest that the thermoregulatory, metabolic and cardiovascular alterations that occur as a result of this increased heat storage capacity contribute to performance enhancement when fluid is ingested during exercise heat stress. 相似文献
8.
Changes in workload are evident during many physical activities. The aim of this study was to assess total substrate metabolism when the temporal placement of a period of higher-intensity work (75% VO 2max ) was varied within a low-intensity exercise session (50% VO 2max ). One experimental trial (higher intensity first) comprised 5 min low-intensity work, followed by 15 min high-intensity work, followed by 40 min low-intensity work. The other trial (low intensity first) comprised 40 min low-intensity work, followed by 15 min high-intensity work, followed by 5 min low-intensity work. The trials were designed to achieve an identical total energy expenditure. Energy expenditure, fat and carbohydrate utilization were estimated by expired gas analysis and compared between conditions. Mean total energy expenditure during the higher-intensity phase was 1076 kJ and 1128 kJ in the high-intensity first and low-intensity first trials respectively (t 6 = -3.76, P = 0.0047). Mean total energy expenditure for the whole trial was 3356 kJ and 3452 kJ in the high-intensity first and low-intensity first trials respectively (t 6 = -3.48, P = 0.0065). Mean whole-trial fat utilization was 1753 kJ and 1857 kJ in the high-intensity first and low-intensity first trials respectively (t 6 = -0.76, P = 0.24). Our findings suggest that changing the temporal placement of higher-intensity work within a low-intensity exercise session has a significant effect on total energy expenditure but not on the rate of fat oxidation. 相似文献
9.
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