Physical profiling in elite professional men's football: Academy, reserve and first team variations in fitness and performance.

We profiled the physical fitness and training and match performance of elite academy (under-18 (U18, n = 23), reserve (RES, n = 15)), and first teams (FT, n = 25) to assess physical readiness for academy-FT progression. Further, we segregated players into player positions, ages, and current versus former academy players that had successfully progressed to FT. Aerobic capacity, anthropometry, and global positioning system- and heart rate-derived performance profiles in training and matches quantified external and internal loads. FT demonstrated 10% more body mass (p < 0.01) with similar adiposity, and ~10% higher aerobic capacity (p < 0.01) versus academy. In training, U18 covered more distances: 727 m (16%) total distance, 115 m (48%) high-speed, and 65 m (79%) sprint distance, and generated 0.63  m/s (8%) higher peak speeds versus FT (all p < 0.01), while FT displayed higher mean speeds: 8 m/min (11%) and 18 m/min (24%) versus U18 and RES (all p < 0.05). In terms of matches, U18 and RES covered more distance: total 539 m (5%) and 567 m (6%) and high-speed distance: 111 m (18%) and 121 m (20%), and displayed higher mean speeds: 13 m/min (11%) and 14 m/min (12%), versus FT (all p <  0.05). Thus, in this club, FT players demonstrated higher aerobic capacity, but not physical performance in training or matchplay. Academy players were not inferior, but displayed different performance behaviours.