Abstract
This study aimed to explore the physical performance differences between professional and reserve male football players within a single A-League club. Transitioning to first-team football is a key milestone in the professionalisation of the reserve players, making it essential to understand the physical demands required to enhance performance and minimise injury risk. It was hypothesised that first team players would be fitter and stronger compared to reserve players across all positions: defenders (D), midfielders (M), and attackers (A). Regarding the locomotor metrics, it was predicted that the reserves would cover greater total distance (TD) during matches and training sessions, but would not perform more high intensity running (HIR) than the first team. A convenience sample of 35 players (first team: n=19; reserves: n=16) from the 2024/2025 season participated in this study. Physical performance metrics included maximal aerobic speed (MAS), countermovement jump (CMJ), barbell hip thrust (BHT), isometric mid-thigh pull (IMTP), isometric adductor (ADD 45°), and isometric hamstring prone test (ISO-Prone). Locomotor metrics, including TD, HIR, sprint distance (SD), number of accelerations (ACC), and decelerations (DEC), were taken from training and matches. The physical performance metrics were expressed as absolute values, whereas the locomotor metrics were normalised to meters per minute (m/min) and actions per minute (a/min). Independent t-tests alongside analysis of covariance (ANCOVA) were conducted to compare first team and reserve players across positions (D, M, and A). Results revealed that first team D (mean difference: 9.4%) and M (11.9%) exhibited lower MAS scores than their reserve counterparts (p<0.002), with MAS showing a decline with age among first team players (p<0.002). In contrast, first-team D displayed significantly higher (20.5%) CMJ scores compared to the reserve D (p<0.002), alongside CMJ performance tending to increase with body weight for first-team players (p<0.017). Additionally, heavier players in both teams produced greater IMTP forces (p<0.018). Reserve A covered significantly greater HIR (60.7%), SD (111.1%) and performed more DEC (90.9%) during matches compared to first team A. In training, first team D (14.2%) and A (22.3%) covered greater TD with a higher frequency of ACC relative to reserves, with most ACC made by first team M (mean difference, D: 85.7%, M: 111.1%, A: 140%). In conclusion, the reserves within this club demonstrated that they already exceed some of the physical capabilities of the first team players. Overall, fewer differences than expected exist between the two teams. It is suggested that any nuanced distinctions were related to the complex interaction between physiology, training environment, and tactical context. Future research should aim to examine these relationships longitudinally across several seasons, combining strength, power, neuromuscular, and locomotor workloads to further understand the physical requirements needed to transition to a professional football team.