Energy requirements of injured soccer players: a doubly labelled water case series from the English Premier League

Accurate estimation of energy requirements is essential for optimising nutritional strategies during injury rehabilitation in professional soccer. This case series examined total daily energy expenditure (TDEE) via doubly labelled water (DLW), energy intake (EI), and body composition across two rehabilitation phases in English Premier League (EPL) players. Case Study 1 (22 years-old, 193 cm, 93.7 kg) involved early-stage hamstring rehabilitation, while Case Study 2 (21 years-old, 186 cm, 88.7 kg) captured the transition from partial (PWB) to full weight-bearing (FWB) during rectus femoris rehabilitation. EI was measured via remote food photography method and 24-hour recalls on two non-consecutive days per case. Body composition was measured via dual-energy X-ray absorptiometry in Case Study 1 at baseline and Day 14. In Case Study 1, TDEE increased by 1013 kcal·day− 1 (Week 1: 3143 kcal·day− 1; Week 2: 4156 kcal·day− 1), accompanied with an increased DLW-estimated EI (Week 1: 2911 kcal·day⁻1; Week 2: 4343 kcal·day⁻¹). Body mass (BM) remained stable (+ 0.10 kg), but fat-free soft-tissue mass (FFSTM) decreased (− 0.50 kg), primarily in the trunk and non-injured leg, while FFSTM in the injured leg was preserved (+ 0.07 kg). In Case Study 2, TDEE increased by 538 kcal·day− 1 (PWB :3175 kcal·day− 1; FWB: 3713 kcal·day− 1) but remained below pre-injury levels (4546 kcal·day− 1). BM reduced in both PWB (-0.3 kg) and FWB phases (-1.2 kg). DLW-estimated EI indicated energy deficits in both phases (PWB: 139 kcal·day− 1; FWB: 557 kcal·day− 1). These findings highlight that energy requirements of EPL players fluctuate across rehabilitation phases, emphasising the importance of individualised nutritional support during rehabilitation.