Carbohydrates in sports nutrition

Peer-reviewed / reviewed during preparation

Position of the working group sports nutrition of the German Nutrition Society (DGE)

Introduction

Among macronutrients, carbohydrates are particularly important for athletic performance [1]. Carbohydrates have a very high energy efficiency and can be metabolized both aerobically and anaerobically [2]. Particularly when oxygen uptake is considered, which is particularly important in endurance sports, the energy yield in terms of the amount of adenosine triphosphate (ATP) per liter of oxygen is higher for carbohydrates than for fatty acids [3]. The total energy yield during anaerobic (2 Mol ATP/Mol glucose) and aerobic (36 Mol ATP/ Mol glucose) glucose metabolism is less than for the metabolism of fatty acids (e.g. 122 ATP/Mol stearic acid), but the flux of energy, i.e. the ATP yield per unit of time is much higher for carbohydrates [4].

Compared to energy yield from fatty acids, ATP resynthesis/unit of time is twice as high for aerobic metabolism of glucose. In the case of anaerobic metabolism of glucose, this value is actually four times higher [5].

Therefore, it has been shown that a high proportion of carbohydrates in the diet can significantly improve physical performance during prolonged, intense physical exercise [6]. Furthermore, there is increasing evidence that the level of carbohydrate stores in the liver and muscles affects training-induced adaptation processes in the body [1, 7, 8].

Abstract

Carbohydrates are an important source of energy during physical exercise. Carbohydrates lead to a higher energy yield and higher energy flux per liter of oxygen than the oxidation of fatty acids. However, the storage capacity for carbohydrates in liver and muscles is limited. Therefore, endurance athletes should include a high proportion of carbohydrates in their daily diet. The individual amount depends on body weight and the extent of physical activity. Energy expenditure during physical exercise results in a gradual depletion of carbohydrate stores. The extent to which carbohydrate stores are depleted is dependent on the duration and intensity of exercise. Therefore, in particular during prolonged intense exercise, performance may be improved by consuming an adequate amount of carbohydrates during exercise. In addition, following a long period of intensive physical activity, rapid post-exercise intake of carbohydrates can help replenish carbohydrate stores more quickly. This position paper sets out current guidelines for the type, amount and timing of carbohydrate intake in sport. It will also discuss the significance of “carbohydrate loading”, the glycemic index, and training without prior intake of carbohydrates.

Keywords: carbohydrates, position statement, sports nutrition, glycogen stores, energy supply

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