Author(s): MCLAUCHLAN, C., BAKER, D., MUSSON, D., Institution: UNIVERSITY OF AUCKLAND , Country: NEW ZEALAND, Abstract-ID: 1658

INTRODUCTION:
Triathlon demands high training volume and intensity, placing athletes at risk of sustained energy deficits. Sustained energy deficits can lead to problematic LEA, impairing physiological functions. While this has been studied in elite triathletes, little has been done in amateur triathletes. This study investigates energy balance and availability, body composition, health and well-being outcomes in amateur triathletes over a 12-week period.
METHODS:
Seventeen participants completed three-day diet records using Intake24, a validated online dietary recall tool, to assess energy intake at 12, 6, and 2 weeks pre-race. Energy expenditure was estimated from wearable devices. Self-reported energy levels, training quality, sleep quality, injuries, menstrual changes and mental well-being were recorded at each time point through a questionnaire. Body composition was assessed via DEXA at baseline and post-race. A post-race questionnaire captured race outcomes and self-perceived nutrition management. Energy deficits were averaged and defined as anything more than -500kcal to account for estimated and self-reported recordings. Two-way ANOVA was used to analyse differences between energy balance and energy deficit athletes' outcomes and Pearson’s for correlations
RESULTS:
The prevalence of sustained energy deficits was 41% across the 12 weeks. Prevalence of deficits at each time point was 47% at 12 weeks, 23% at 6 weeks, and 35% at 2 weeks. There was a day-of-week pattern where on Saturdays, 47–65% of participants were in energy deficit, compared with 12–41% on Thursdays and 23.5–41% on Fridays. At all time points, athletes in energy deficits had significantly poorer mental well-being (p=0.0058, 0.05, 0.024), less sleep (p=0.0071, 0.0321, 0.0468), and lower energy levels (p=0.0282, 0.0115, 0.0352). Overall, they had more injuries (p= 0.0345), more menstrual disturbances (p= 0.0476), losses in spinal bone mineral density (p=0.002) and more muscle cramps during their race. A strong positive correlation was found between the degree of energy balance and hours of sleep (p=0.0005, r=0.7530). Training volume remained similar to those in energy balance across the 12 weeks, suggesting potential behavioural rigidity or compulsive training tendencies.
CONCLUSION:
Sustained energy deficits are common in triathletes and, in our cohort, were linked to several adverse health and well-being outcomes. These findings highlight the importance of long-term monitoring across the training cycle to identify athletes at risk of LEA. Cross-sectional assessments may have produced very different prevalence estimates, as some athletes experienced isolated days of energy balance yet still accumulated a substantial overall deficit. This study reinforces the need for practical methods to assess and address fuelling adequacy, as well as improved education to help triathletes understand the impact of both unintentional and intentional under fuelling.