Pre‐Season Total Energy Expenditure and Dietary Intake of Professional Male Soccer Players: A Doubly Labelled Water Study

ABSTRACT Limited data exist describing how professional footballers meet their energy requirements during pre‐season, a phase characterised by increased training volume and a progressive shift from general conditioning to football‐specific preparation. This study quantified total, resting, and activity energy expenditure (AEE), diet‐induced thermogenesis, water turnover, and dietary intake in six professional male soccer players (age: 25 ± 1 year; height: 182.5 ± 10.1 cm; body mass: 77.8 ± 8.2 kg). Players were studied across 14 consecutive days, representing training‐only and training‐plus‐match microcycles. Total energy expenditure (TEE) was measured using doubly labelled water, resting energy expenditure (REE) by indirect calorimetry and dietary intake using the remote food photography method. Fourteen‐day mean TEE, REE, AEE and water turnover were 13.25 ± 1.31 MJ⋅day−1, 7.96 ± 0.89 MJ⋅day−1, 4.20 ± 1.03 MJ⋅day−1, 5.16 ± 0.66 L⋅day−1, respectively. Physical activity level was 1.67 ± 0.16 AU. Energy, carbohydrate, protein, and fat intakes were 10.95 ± 1.52 MJ⋅day−1, 2.8 ± 0.6 g⋅kg−1⋅day−1, 2.2 ± 0.4 g⋅kg−1⋅day−1, and 1.5 ± 0.4 g⋅kg−1⋅day−1, respectively. Total energy expenditure was not significantly different between training‐only and training‐plus‐match microcycles (+1.89 ± 1.98 MJ⋅day−1; ES = 0.95 ± 1.08; p = 0.100). No significant differences were observed in energy or macronutrient intake across weekly microcycles (p > 0.068) or between days (p > 0.144). Players did not achieve energy balance or align dietary intake with day‐to‐day training demands, suggesting limited nutrition periodisation during pre‐season. These findings highlight the need for practitioners to implement strategies supporting fuelling, recovery and adaptation during this critical phase.