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.

Keywords: nutrition; team sport; training.

FIGURE 1

An overview of the schedule for the fourteen‐day assessment period. Participant positions are shown in brackets. CD, central defender; CM, central midfielder; DLW, doubly labelled water; F, forward; GK, goalkeeper; REE, resting energy expenditure; WD, wide defender.

FIGURE 2

Training and match duration (A), total distance (B), high‐speed running (C), sessional rating of perceived exertion (D), time in sedentary activity (E), time in light activity (F) and step count (G) across weeks. White bars represent a pre‐season microcycle. Light grey bars represent a one‐match microcycle. ^aSignificant difference from one‐match microcycle, p < 0.05. Black circles represent individual outfield participants. White triangle represents participant 5 (goalkeeper). Data not included for participant 6 (injured). Sessional rating of perceived exertion (sRPE). Arbitrary units (AU).

FIGURE 3

Training and match duration (A), total distance (B), high‐speed running (C), sessional rating of perceived exertion (D), time in sedentary (E), time in light activity (F) and step count (G) across days. White bars represent single training sessions. Light grey bars represent double training sessions. Grey bars represent match days. Dark grey bars represent rest days including no training sessions. Black circles represent individual outfield participants. White triangle represents participant 5 (goalkeeper). Data not included for participant 6 (injured). ^bSignificant difference from single training session, p < 0.05. ^cSignificant difference from match, p < 0.05.

FIGURE 4

Total energy expenditure (A), activity energy expenditure (B), physical activity level (C) and energy availability (D). The white bars represent the pre‐season microcycle. The light grey bars represent the one‐match microcycle. Black circles represent individual outfield participants. White triangle represents participant 5 (goalkeeper). Values were removed for participant 6 (injured). Arbitrary units (AU).

FIGURE 5

Energy intake (A), protein intake (B), relative protein intake (C), carbohydrate intake (D), relative carbohydrate intake (E), fat intake (F) and relative fat intake (G) across microcycles. The white bars represent the pre‐season microcycle. The light grey bars represent the one‐match microcycle. Black circles represent individual outfield participants. White triangle represents participant 5 (goalkeeper). Values were removed for participant 6 (injured).

FIGURE 6

Energy intake (A), protein intake (B), relative protein intake (C), carbohydrate intake (D) relative carbohydrate intake (E), fat intake (F) and relative fat intake (G) across days. White bars represent training days including one session. Light grey bars represent training days including two sessions. Grey bars represent match days. Dark grey bars represent rest days including no training sessions. Black circles represent individual outfield participants. White triangle represents participant 5 (goalkeeper). Values were removed for participant 6 (injured).

FIGURE 7

Energy and macronutrient distribution across meals. Absolute energy intake (A), relative energy intake (B), absolute carbohydrate intake (C), relative carbohydrate intake (D), absolute protein intake (E), relative protein intake (F), absolute fat intake (G) and relative fat intake (H). ^aSignificant difference from before breakfast, p < 0.05. ^bSignificant difference from breakfast, p < 0.05. ^cSignificant difference from morning snack, p < 0.05. ^dSignificant difference from lunch, p < 0.05. ^eSignificant difference from afternoon snack, p < 0.05. ^fSignificant difference from dinner, p < 0.05. ^gSignificant difference from evening snack, p < 0.05. Black circles represent individual outfield participants. White triangle represents participant 5 (goalkeeper). Values were removed for participant 6 (injured).