LAUSR

Young athletes undergo many anatomical and physiological changes during the first 2 decades of life as a result of growth and maturation. Such changes influence a young athlete’s nutritional requirements and it is therefore inappropriate to apply nutritional guidelines for adult athletes to this population. Nutritional recommendations for young athletes should not only focus on sporting performance but should also meet the requirements to ensure optimal growth, maturation, and physical development. This review article provides an overview of the nutritional recommendations for young athletes based on the best available literature from a range of sports. INTRODUCTION AND OVERVIEW OF YOUNG ATHLETES D espite some young athletes competing against adults at the highest level, young athletes cannot simply be considered “mini adults.” As a young athlete progresses from childhood (years up until the onset of adolescence) through adolescence (identified with the onset of sexual maturation/puberty) and into adulthood (achieved once fully mature, i.e., fully ossified skeletal system, a fully functioning reproductive system, or the attainment of adult stature), they undergo many anatomical, physiological, and metabolic changes as a result of biological growth and maturation (56). Growth and maturation is a complex process that is influenced by the interaction of genes, hormones, nutrients, and the environments in which the individual lives (35). The primary focus for practitioners working with young athletes should be to ensure that the nutritional requirements for growth and maturation are met among their athletes (16). There are several differences in substrate storage and substrate metabolism in young athletes compared to adult athletes, with numerous physiological and metabolic changes accompanying growth and maturation in the young athlete. These changes in physiology and metabolism subsequently influence the nutritional requirements of the young athlete (Table 1). There are a number of interlinked key factors that influence a young athlete’s nutritional requirements: (a) their current anthropometric profile, rate of growth, and maturity status/timing, (b) their current physiological and metabolic capabilities, and (c) their sport and exercise demands. Before developing sport-specific nutritional requirements for young athletes, it is essential to gain a greater understanding of these factors and the interplay between them. It should also be noted that mostly, any sex differences in nutritional requirements are primarily driven by differences in size between boys and girls, with the exception of iron, which has been reviewed in detail elsewhere (3). Consequently, macronutrient (carbohydrate, fat, and protein) requirements (particularly carbohydrate and protein) are prescribed per kilogram of body mass, to account for individual differences in body size. ENERGY CONSIDERATIONS A young athlete’s energy intake is provided through the consumption of the macronutrients, carbohydrate, fat, and protein. The energy intake of each young athlete should be dictated by their total energy expenditure (i.e., their energy requirements) to optimize not only growth and maturation but also stimulate training adaptations, promote recovery and of course, sporting performance. Therefore, before giving specific macronutrient recommendations, it is first essential to understand the typical energy expenditures experienced by young athletes from different sports but also those at different ages/stages of maturation (within a certain sport). Total energy expenditure is composed of 3 contributing factors: (a) basal metabolism (typically known as resting metabolic rate; the amount of energy required to maintain normal homeostatic physiological function in a rested, fasted, and thermoneutral state); (b) Address correspondence to Marcus P. Hannon, [email protected].