From Intention to Execution: Pre‐Race Nutrition Behaviours, Influences, and Performance Outcomes in Female Endurance Athletes at the IRONMAN World Championships

Endurance competition preparation involves complex psychological, logistical, and sociocultural factors. This study investigated the pre‐race nutrition practices of female endurance athletes, by applying a newly developed extended Theory of Planned Behaviour, including behavioural execution to the framework to capture real‐world influences (ETPB‐X). Using a convergent mixed‐methods design, 27 female triathletes competing at the 2024 IRONMAN World Championships completed questionnaires, 48‐h food diaries, and semi‐structured interviews before and after the race. Quantitative data ( n = 23) were analysed for energy and macronutrient intake, whereas qualitative data were thematically coded using the conceptual ETPB‐X framework, incorporating attitudes, subjective norms, perceived behavioural control (PBC), utilitarian drivers, and behavioural execution. Only 26% (6/23) of athletes achieved carbohydrate loading guidelines (8–12 g·kg −1 body mass (BM)·day −1 ), with an overall mean intake of 6.4 ± 2.1 g·kg −1 BM. Higher carbohydrate intake correlated with faster finish times ( r = −0.50, p = 0.035), whereas fibre intake was positively associated with gastrointestinal (GI) symptom severity ( r = 0.85, p < 0.001). Qualitative findings revealed that adherence to diet plans was influenced by PBC, travel logistics, emotional regulation, and athlete identity. This study provides a novel application of the ETPB‐X framework to pre‐race nutrition in female endurance athletes. Athletes often under‐achieve carbohydrate loading targets despite awareness, with success determined as much by psychosocial and contextual factors as by knowledge. Practically, enhancing PBC, improving planning/preparation, and delivering clear goal‐aligned education may bridge the intention‐behaviour gap. Integrating behavioural frameworks into performance nutrition offers a pathway towards more effective athlete‐centred interventions.