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Luc van Loon geciteerd in The New York Times over het belang van voeding en in het bijzonder specifieke sportvoeding voor de atleet
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Use of intramuscular triacylglycerol as a substrate source during exercise in humans
No full textFat and carbohydrate are the principal substrates that fuel aerobic ATP synthesis in skeletal muscle. Most endogenous fat is stored as triacylglycerol in subcutaneous and deep visceral adipose tissue. Smaller quantities of triacylglycerol are deposited as lipid droplets inside skeletal muscle fibers. The potential role of intramyocellular triacylglycerol (IMTG) as a substrate source during exercise in humans has recently regained much of its interest because of the proposed functional relationship between IMTG accumulation and the development of skeletal muscle insulin resistance. Exercise likely represents an effective means to prevent excess IMTG accretion by stimulating its rate of oxidation. However, there is much controversy on the actual contribution of the IMTG pool as a substrate source during exercise. The apparent discrepancy in the literature likely stems from methodological difficulties that have been associated with the methods used to estimate IMTG oxidation during exercise. However, recent studies using stable isotope methodology, 1H-magnetic resonance spectroscopy, and electron and/or immunofluorescence microscopy all support the contention that the IMTG pool can function as an important substrate source during exercise. Although more research is warranted, IMTG mobilization and/or oxidation during exercise seem to be largely determined by exercise intensity, exercise duration, macronutrient composition of the diet, training status, gender, and/or age. In addition, indirect evidence suggests that the capacity to mobilize and/or oxidize IMTG is substantially impaired in an obese and/or Type 2 diabetic state. As we now become aware that skeletal muscle has an enormous capacity to oxidize IMTG stores during exercise, more research is warranted to develop combined exercise, nutritional, and/or pharmacological interventions to effectively stimulate IMTG oxidation in sedentary, obese, and/or Type 2 diabetes patients
De menselijk motor : the human engine
Full text linkInauguratie Prof.dr. Luc J.C. van Loon, benoemd in de Faculty of Health Medicine and Life Sciences tot bijzonder hoogleraar ‘Fysiologie van Inspanning met bijzonder aandacht voor de rol van voeding
Nutritional strategies to attenuate muscle disuse atrophy
No full textSituations such as recovery from injury or illness require otherwise humans to undergo periods of disuse, which lead to considerable losses skeletal muscle mass and, subsequently, numerous negative health has been established that prolonged disuse (>10 days) leads to a decline and postprandial rates of muscle protein synthesis, without an apparent muscle protein breakdown. It also seems, however, that an early and (1-5 days) increase in basal muscle protein breakdown may also disuse atrophy. A period of disuse reduces energy requirements and Consequently, food intake generally declines, resulting in an inadequate protein consumption to allow proper muscle mass maintenance. Evidence that maintaining protein intake during a period of disuse attenuates atrophy. Furthermore, supplementation with dietary protein and/or acids can be applied to further aid in muscle mass preservation during Such strategies are of particular relevance to the older patient at risk developing sarcopenia. More work is required to elucidate the impact of basal and postprandial rates of muscle protein synthesis and breakdown. information will provide novel targets for nutritional interventions to attenuate muscle disuse atrophy and, as such, support healthy aging
Role of dietary protein in post-exercise muscle reconditioning
No full textDietary protein ingestion after exercise stimulates muscle protein inhibits protein breakdown and, as such, stimulates net muscle protein following resistance as well as endurance type exercise. Protein and/or immediately after exercise has been suggested to facilitate the muscle adaptive response to each exercise session, resulting in more muscle reconditioning. A few basic guidelines can be defined with regard preferred type and amount of dietary protein and the timing by which should be ingested. Whey protein seems to be most effective to increase post-exercise muscle protein synthesis rates. This is likely attributed rapid digestion and absorption kinetics and specific amino acid Ingestion of approximately 20 g protein during and/or immediately after is sufficient to maximize post-exercise muscle protein synthesis rates. Additional ingestion of large amounts of carbohydrate does not further post-exercise muscle protein synthesis rates when ample protein is ingested. Dietary protein should be ingested during and/or immediately cessation of exercise to allow muscle protein synthesis rates to reach levels. Future research should focus on the impact of the timing of provision throughout the day on the adaptive response to more prolonged training. Copyright (c) 2013 Nestec Ltd., Vevey/S. Karger AG, Basel
The use of carbohydrates during exercise as an ergogenic aid.
No full textCarbohydrate and fat are the two primary fuel sources oxidized by tissue during prolonged (endurance-type) exercise. The relative these fuel sources largely depends on the exercise intensity and greater contribution from carbohydrate as exercise intensity is Consequently, endurance performance and endurance capacity are largely by endogenous carbohydrate availability. As such, improving carbohydrate availability during prolonged exercise through carbohydrate ingestion dominated the field of sports nutrition research. As a result, it has well-established that carbohydrate ingestion during prolonged (>2 h) moderate-to-high intensity exercise can significantly improve endurance performance. Although the precise mechanism(s) responsible for the effects are still unclear, they are likely related to the sparing of muscle glycogen, prevention of liver glycogen depletion and subsequent development of hypoglycemia, and/or allowing high rates of carbohydrate oxidation. Currently, for prolonged exercise lasting 2-3 h, athletes are to ingest carbohydrates at a rate of 60 g.h-1 (~1.0-1.1 g.min-1) to maximal exogenous glucose oxidation rates. However, well-trained athletes competing longer than 2.5 h can metabolize carbohydrate up to (~1.5-1.8 g.min-1) provided that multiple transportable carbohydrates ingested (e.g. 1.2 g.min-1 glucose plus 0.6 g.min-1 of fructose). small amounts of carbohydrate ingestion during exercise may also enhance performance of shorter (45-60 min), more intense (>75 % peak oxygen VO2peak) exercise bouts, despite the fact that endogenous carbohydrate unlikely to be limiting. The mechanism(s) responsible for such ergogenic properties of carbohydrate ingestion during short, more intense exercise has been suggested to reside in the central nervous system. Carbohydrate ingestion during exercise also benefits athletes involved in sports. These athletes are advised to follow similar carbohydrate strategies as the endurance athletes, but need to modify exogenous intake based upon the intensity and duration of the game and the endogenous carbohydrate stores. Ample carbohydrate intake is also those athletes who need to compete twice within 24 h, when rapid endogenous glycogen stores is required to prevent a decline in support rapid post-exercise glycogen repletion, large amounts of carbohydrate (1.2 g.kg-1.h-1) should be provided during the acute from exhaustive exercise. For those athletes with a lower threshold for carbohydrate ingestion immediately post-exercise, and/or muscle re-conditioning, co-ingesting a small amount of protein (0.2-0.4 g.kg-1.h-1) with less carbohydrate (0.8 g.kg-1.h-1) may provide a to achieve similar muscle glycogen repletion rates
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