Author(s): LEYSEN, M., AMPE, T., DECROIX, L., DE PAUW, K., ROELANDS, B., MEEUSEN, R., Institution: VRIJE UNIVERSITEIT BRUSSEL (VUB), Country: BELGIUM, Abstract-ID: 2057

INTRODUCTION:
Relative Energy Deficiency in Sport (RED-S) represents a critical risk for endurance athletes, particularly during intensive stage racing. High training demands and limited opportunities for adequate energy intake may create an energy imbalance. This study investigated whether elite female cyclists experience an energy deficit during a Grand Tour (GT) and examined how energy availability relates to their dietary strategies and physiological adaptations.
METHODS:
Ten elite female cyclists (26.4±4.0 years, BMI 20.3±0.8 kg/m², FTP 4.9±0.4 W/kg) from a World Tour team participated in this quasi-experimental study. Dietary intake, training and racing data were collected before (PRE) and during the Giro Donne (n=3) or Tour de France Femmes (n=7). Energy expenditure was calculated from training data and basal metabolic rate (mean 1325.6±49.9 kcal/day). PRE–POST differences were analysed using linear mixed-effects models.
RESULTS:
During the GT, Training Stress Score was significantly higher (236.8±40.7 vs 91.3±21.6, p<0.001), raising active energy expenditure to 2755.4±706.6 kcal/day (mean-diff 1532.5, p<0.001) and total daily energy expenditure to 4687.4±653.9 kcal/day. Although cyclists substantially increased energy intake to 4211.0±747.8 kcal/day (mean-diff 1287.8, p<0.001), primarily through increased sugar (512.3±89.6 vs 259.6±35.6 g, p<0.001) and starch (219.1±43.4 vs 171.3±35.3 g, p=0.009), this did not compensate for total expenditure (p<0.001), leaving a systematic energy deficit of on average 476.4±440.2 kcal/day. Protein (151.1±15.8 vs 144.0±24.8 g, p=0.347) and fibre (30.0±4.8 vs 31.6±5.9 g, p=0.508) remained stable, whereas fat intake decreased (64.1±3.2 vs 57.0±5.7 g, p=0.001).
CONCLUSION:
Elite female cyclists adopt a high-carbohydrate dietary strategy during Grand Tours but experience a persistent energy deficit of on average 476 kcal/day despite maximising practical energy intake. This mismatch between energy expenditure and intake reflects a state of relative energy deficiency that may increase susceptibility to fatigue, impaired recovery, immunosuppression and long-term health consequences. These findings highlight the practical challenges of meeting energy demands during stage racing and support the need for individualised strategies, including optimised pre- and post-stage nutrition, to minimise RED-S risk. Future research should explore whether this energy gap correlates with performance outcomes, hormonal markers of RED-S or recovery metrics during a GT.