Kinetic and Kinematic Effects of Flag-Carrying on Change of Direction and Sprinting Performance in Assistant Referees.

Grazer, J, Reed, WJ, Mangine, G, Hester, G, Huet, K, and Edwards, W. Kinetic and kinematic effects of flag-carrying on change of direction and sprinting performance in assistant referees. J Strength Cond Res 40(3): e292-e297, 2026-Within competitive soccer, assistant soccer referees (AR) are expected to keep up with the top speed of players on the field, despite potentially being hindered by holding a flag down by their side. Their ability to keep up with speed-of-play can determine effectiveness of decisions on the field, yet standardized AR fitness assessments do not consider these challenges. The purpose of this study was to examine kinetic and kinematic effects of flag-carrying within sprinting and change-of-direction performance in ARs. Eighteen male referees (age: 31 ± 9 years, height: 1.78 ± 0.60 m, mass: 81.9 ± 10.6 kg) performed 6 trials each of 60-m sprints and a standardized change-of-direction ability test (CODA). Each referee ran 3 trials with and without a flag in a randomized order. Two-way repeated measures analysis of variance (analyses of variance) was used to determine differences between trials and condition. Total sprint time (2.52%, p < 0.01) and total step count (1.86%, p < 0.01) decreased during the non-flag-carrying condition. Kinetic and kinematic variables including force, velocity, and power within the top speed phase also saw increases (p ≤ 0.01), but none were observed within the acceleration phase or CODA test (p > 0.05). Flag-carrying seems to negatively affect top speed but not acceleration or change of direction performance. Practitioners should use methods that can enhance top-end sprinting performance for ARs due to the potential hindrance of top-end sprinting performance while carrying a flag. Future studies may benefit by assessing body position to determine specific aspects of sprinting that are negatively affected by flag carrying.