Lower-Limb Explosive Power, Inter-Limb Asymmetry, and Eccentric Utilisation Ratio in Male Professional Football Referees: A Cross-Sectional Study by Officiating Role and League Level

Background: The lower-limb neuromuscular profile of football match officials remains poorly characterised, and inter-limb asymmetry and the eccentric utilisation ratio (EUR) have not been examined in this population. The objective was to characterise jump-derived neuromuscular performance in male professional referees and to test the hypotheses that referees outperform assistant referees and that asymmetry prevalence is independent of competitive level. Methods: In this retrospective cross-sectional study, 125 male Bulgarian First and Second League officials (33.4 ± 6.1 years) completed squat jump (SJ), countermovement jump (CMJ), and unilateral CMJ testing with an optical system. Two-way analyses of covariance (Type III) were adjusted for age and body mass, with Hedges’ g effect sizes. Results: Trial-to-trial reliability was excellent after exclusion of five technically failed trials (ICC = 0.92–0.95). Referees outperformed assistant referees in SJ (g = 0.68), CMJ (g = 0.70), and estimated relative peak power (g = 0.70; all Holm-adjusted p = 0.001). First League officials were older (36.5 vs. 30.5 years), and no league effect remained after adjustment (p ≥ 0.50). Median asymmetry was 8.5%; 46.8% of officials exceeded 10%, independent of league and role. Mean EUR was 1.01 ± 0.06. Conclusions: Officiating role, rather than competitive level, was associated with lower-limb explosive performance. Asymmetry and EUR values warrant longitudinal investigation.