Physical demands and patterns of Portuguese football referees: a case study Short Title: Demands of Football referees in Portugal

Abstract

This study quantified the match-related external and internal physical demands and activity patterns of Portuguese Football field referees (FRs) and assistant referees (ARs) across different categories. A total of 8 FRs and 7 ARs were monitored during 98 official competitions using GPS with embedded heart rate sensors, and post-match rate of perceived exertion (RPE) was collected. Descriptive statistics and between-group comparisons were applied to examine differences between roles, and the interrelationship between external and internal loads was explored using Pearson’s correlation. FRs covered substantially more total distance and distance per minute than ARs (7.49 ± 2.47 vs 5.64 ± 1.25 km; 78.68 ± 14.56 vs 55.88 ± 7.78 m·min⁻¹; both p < .001), and accumulated more medium-velocity running, whereas ARs reached higher maximal speeds and performed more high-speed running bouts and decelerations (p ≤ .031). ARs also reported higher perceived exertion than FRs (6.80 ± 0.68 vs 4.23 ± 1.65, p < .001), and RPE showed strong positive correlations with accelerations (r = 0.674, p < .001) and decelerations (r = 0.686, p < .001). Heart rate data from FRs showed most match time spent in low-to-moderate intensity zones, with minimal exposure to very high intensities. The referees were exposed to substantial, role-dependent external and internal loads even in a non-professional regional setting. The distinct demands of FRs and ARs, support the need for role- and category-specific conditioning, monitoring and recovery strategies used. These findings provide practical benchmarks to inform training prescription, load management and development pathways for football referees.