Calories burned, water and minerals lost during running

Calculation of calories burned running During running, energy expenditure is equal to: 0.85-1.05 kcal/kg of body weight/km The range is due to the fact that athletes with a “cheaper” athletic technique expend less than those with a less refined technique. Moreover, we must underline that  who have recently started running have expenditures even higher than […]

Glycogen: an efficient storage form of energy in aerobic conditions

What is the net energy yield for the oxidation of a glucose unit from glycogen in aerobic conditions? In aerobic conditions, the oxidation of a free glucose to CO2 and H2O (glycolysis, Krebs cycle and oxidative phosphorylation) leads to the net production of about 30 molecules of ATP. Glucose from the action of glycogen phosphorylase: glucose-1-phosphate […]

Maltodextrin, fructose and endurance sports

Carbohydrate ingestion can improve endurance capacity and performance. The ingestion of different types of carbohydrates, which use different intestinal transporters, can: increase total carbohydrate absorption; increase exogenous carbohydrate oxidation; and therefore improve performance. Glucose and fructose When a mixture of glucose and fructose is ingested (in the analyzed literature, respectively 1.2 and 0.6 g/min, ratio 2:1, for […]

Prolonged exercise and carbohydrate ingestion

During prolonged exercise (>90 min), like marathon, Ironman, cross-country skiing, road cycling or open water swimming, the effects of supplementary carbohydrates on performance are mainly metabolic rather than central and include: the provision of an additional muscle fuel source when glycogen stores become depleted; muscle glycogen sparing; the prevention of low blood glucose concentrations. How many carbohydrates should […]

Carbohydrate ingestion during exercise of relatively short duration and high intensity

Intermittent high intensity exercise and carbohydrate ingestion Carbohydrate ingestion during intermittent high intensity or prolonged (>90 min) sub-maximal exercise can: increase exercise capacity; improve exercise performance; postpone fatigue. The intake of very small amounts of carbohydrates or carbohydrate mouth rinsing (for example with a 6% maltodextrin solution) may improve exercise performance by 2-3% when the […]

Hydration before endurance sports

Dehydration and endurance sports In endurance sports, like Ironman, open water swimming, road cycling, marathon, or cross-country skiing, the most likely contributors to fatigue are dehydration and carbohydrate (especially liver and muscle glycogen) depletion. Pre-hydration Due to sweat loss needed to dissipate the heat generated during exercise, dehydration can compromise exercise performance. It is important to […]

Ingestion of solid, liquid or gel carbohydrates 60 min before exercise

The form of carbohydrates ingested before exercise may have different effects on both metabolism and performance. Moreover, the ingestion of solid foods slows gastric empty, digestion and absorption rates compared with liquid foods and this has a different impact on glycemia. For these reasons, several studies have investigated the effects of the form of carbohydrates on […]

Hypoglycemia and carbohydrate ingestion 60 min before exercise

Hypoglycemia: strategies to limit it in susceptible subjects From several studies it appears that the risk of developing hypoglycemia (blood glucose < 3.5 mmol /l or < 63 mg/l) is highly individual: some athletes are very prone to develop it and others are much more resistant. A strategy to minimize glycemic and insulinemic responses during exercise is to delay […]

Carbohydrate ingestion 60 min before exercise

Introductory statement An high-carbohydrate diet in the days before exercise, as well as ingestion of meals high in carbohydrate 3-4 h before exercise, better if with low glycemic index, can have positive effects on athlete’s performance. For many years it has been suggested that ingestion of carbohydrates 30-60 min before exercise may adversely affect performance because […]

Carbohydrate loading before competition

Carbohydrate loading and endurance exercise Carbohydrate loading is a good strategy to increase fuel stores in muscles before the start of the competition. What does the muscle “eat” during endurance exercise? Muscle “eats” carbohydrates, in the form of glycogen, stored in the muscles and liver, carbohydrates ingested during the exercise or just before that, and fat. During endurance […]

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