BJSM energy intake (EI) and the energy expenditure required to support homoeostasis, health and the activities of daily living, growth and sporting activities. It is also evident that the clinical phenomenon is not a triad of three entities of EA, menstrual function and bone health, but rather a syndrome resulting from relative energy deficiency that affects many aspects of physiological function including metabolic rate, menstrual function, bone health, immunity, protein synthesis, cardiovascular and psychological health. In addition, it is evident that relative energy deficiency also affects men. Therefore, a new terminology is required to more accurately describe the clinical syndrome originally known as the Female Athlete Triad. Based on its interdisciplinary expertise, the IOC Consensus group introduces a more comprehensive, broader term for the overall syndrome, which includes what has so far been called the ‘Female Athlete Triad’: Relative Energy Deficiency in Sport (RED-S). The syndrome of RED-S refers to impaired physiological function including, but not limited to, metabolic rate, menstrual function, bone health, immunity, protein synthesis, cardiovascular health caused by relative energy deficiency. The underlying problem of RED-S is an inadequacy of energy to support the range of body functions involved in optimal health and performance. EA is calculated as EI minus the energy cost of exercise relative to fat-free mass (FFM) and in healthy adults, a value of 45 kcal/kg FFM/day equates energy balance.7 Low EA, which occurs with a reduction in EI and/or increased exercise load, causes adjustments to body systems to reduce energy expenditure, leading to disruption of an array of hormonal, metabolic and functional characteristics.7 DE underpins a large proportion of cases of low EA, but other situations, such as a mismanaged programme to quickly reduce body mass/fat or an inability to track EI with an extreme exercise commitment, may occur without such a psychological overlay.7 Although the literature on low EA has focused on female athletes, it has also been reported to occur in male athletes.8 Prevalence studies of low EA in male athletes have been few, however, low EA appears to occur among the same at risk sports as for female athletes: the weight sensitive sports in which leanness and/or weight are important due to their role in performance, appearance or requirement to meet a competition weight category.8 16 Sport & Geneeskunde | september 2014 | nummer 4 Although simple messages about optimal, tolerable and unsafe levels of EA have been provided9 and bone formation markers11 there are some caveats in the science. First, the complex dose–response relationship between reduction in EA and the disruption of various hormones10 vary in nature and thresholds. Therefore, the cost of any energy mismatch should be carefully considered before it is implemented. A second caveat is that it is now known that the resting metabolic rate in athletes of small body size is underestimated in the linear scaling of EA relative to LBM/ FFM.12 apply as cleanly to free-living athletes. Numerous studies in female athletes have failed to find clear thresholds or associations between field determinations of low EA and objective measures of energy conservation such as metabolic hormones13 and menstrual disturbances.14 It is possible that other factors seen in free-living populations such as psychological stress, greater variability in between-day and within-day energy deficiency or dietary characteristics interact with each other to alter the effects of low EA. Disordered eating The disordered eating (DE) continuum starts with appropriate eating and exercise behaviours, including healthy dieting and the occasional use of more extreme weight loss methods such as short-term restrictive diets (<30 kcal/kg FFM/day).15 The continuum ends with clinical eating disorThese EDs have many features in common, and athletes frequently move among them.8 ders (EDs), abnormal eating behaviours, distorted body image, weight fluctuations, medical complications and variable athletic performance. The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) diagnostic classifications for EDs include anorexia nervosa, bulimia nervosa, binge ED and other specified and unspecified feeding or ED.16 The pathogenesis of EDs is multifactorial with cultural, familial, individual and genetic/biochemical factors playing roles.17 In addition, factors specific to sport such as dieting to enhance performance, personality factors, pressure to lose weight, frequent weight cycling, early start of sport-specific training, overtraining, recurrent and non-healing injuries, inappropriate coaching behaviour and regulations in some sports have been suggested.8 The prevalence of DE is about 20% and 13% among adult and adolescent female elite athletes, and 8% and 3% in adult and adolescent male elite athletes, respectively.15 cantly among sports.15 18 The prevalence differs signifiFinally, findings from laboratory settings may not Pagina 15
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Sport & Geneeskunde nummer 4 | november 2014 Lees publicatie 43Home