Uncoupling exposure from disease: improving epidemiological rigour in the study of low energy availability and its translation to practice in elite female athletes

Abstract

Optimal health is critical for an athlete’s success throughout and beyond their sporting career. Adequate energy intake is a key component in the prevention of negative health outcomes. Low energy availability (LEA) is a physiological state whereby an individual’s energy intake is insufficient for normal physiological functioning in addition to their exercise energy expenditure. Chronic exposure to this state results in marked impairments to multiple body systems in males and females. The outcomes of LEA in females have been well-documented and are described by two models: The Female Athlete Triad (“Triad”) and Relative Energy Deficiency in Sport (REDs). The Triad model describes the causal role of LEA in impaired bone health and reproductive function. The REDs model expands on this and describes detrimental health and performance consequences associated with LEA exposure, occurring in almost all body systems in both male and female athletes. Consequences of chronic exposure to LEA are prevalent in athletes, resulting in time loss, impeded success and the potential for lifelong health complications. Much of the research on the outcomes included in the Triad and REDs models has focussed on endurance athletes. The first study of this thesis established the prevalence of outcomes included in the REDs model, within a mixed-sport cohort including team sports and sports that require weight categories for competition. Most participants (80%) demonstrated physiological impairments, with a high prevalence of impaired function of the immunological, gastrointestinal, and haematological systems. Practitioners should be aware that symptoms included in the REDs model are prevalent, despite athletes continuing to undertake training and competition with these impairments. The second study of this thesis explored the utility of a commonly used tool – the Low Energy Availability in Females Questionnaire (LEAF-Q) – in a mixed-sport cohort. Despite its original validation in endurance athletes for the assessment of risk of the Triad, it is used widely in research and clinical practice to assess risk of LEA exposure and/or outcomes included in the Triad and REDs models, in varying athletic populations. Diagnostic statistics demonstrated that the LEAF-Qii tool was able to rule out risk of LEA-related conditions in mixed-sport athletes, however it was unable to identify “high-risk” athletes, nor could it be used as a surrogate diagnostic tool to detect outcomes associated with LEA exposure in its current form. The LEAF-Q is one of many methods utilised within the literature. A critical analysis of the methodologies for the assessment of energy availability (EA) and the outcomes included in the Triad and REDs models is presented. Marked inconsistencies in these methods exist and there is a need for consensus on direct methods of assessment of EA and indirect markers of LEA exposure. Recommendations for optimising field- and/or laboratory-based methodologies are proposed to improve transferability of study findings and understanding of disease/outcome progression. The methodology review highlighted the limited inclusion of epidemiological concepts within much of the literature within this field, as well as the Triad and REDs models. Key terminology is defined and translated to clinical practice to encourage the use of precise and correct terminology to promote scientific rigour. Adopting these key fundamentals will enhance understanding of the role of LEA exposure in the development of the impairments included in the Triad and REDs models and inform prevention and intervention strategies. The aim of this thesis was to explore LEA and its associated outcomes in elite female athletes. LEA exposure is a likely contributor to impaired health and performance in Australian female athletes. Understanding risk factors and the necessary cause(s) will assist in determining the exact nature of this relationship. Consensus on methodologies for assessment of EA and the outcomes included in the Triad and REDs models will support high-quality research which can then inform improved clinical practice.

Date of Award	2023
Original language	English
Supervisor	Gordon WADDINGTON (Supervisor)