ACTIVITY PROFILE AND PHYSIOLOGICAL DEMANDS OF TOP CLASS ASSISTANT REFEREEING IN SOCCER

Abstract

To examine the movement pattern and physiological demands of top-class assistant refereeing in soccer, computerized time motion analyses were performed on 12 assistant referees in 18 competitive top-level matches. Heart rates (HR) were recorded continuously and blood lactates were measured in blood samples taken immediately after each half. In addition, 10 of the assistant referees (41 (range: 35–47) yrs, 181 (175–189) cm, 79.7 (69.1–90.2) kg, 44.7 (40.9–49.8) mlO2/min/kg) carried out a laboratory treadmill test. To study sprint performance during the game 12 assistant referees performed a repeated sprint protocol (3x30-m sprints separated by 25s) immediately before and after additional 6 competitive games. Total distance covered by the top class assistant referees was 7.18 (5.78–8.16) km of which 1.10 (0.86–1.43) km was high intensity running and 1.03 (0.12–2.09) km was sideways running. The total number of match activities recorded was 943 (807–1115) corresponding to a change in activity every 6 s on average. The mean distance of the 76 (55–103) high intensity runs recorded was 14 m and 89% of those were shorter than 25 m. Mean HR was 137 (117–159) beats/min corresponding to 74 (65–88)% of HRmax or, estimated from treadmill HR-VO2 relationships, 66 (56–80)% of VO2max. Blood lactate was 4.7 (1.6–11.0) and 4.8 (1.1–13.7) mmol/l after first and second half, respectively. The peak distance to the off-side line was higher (p < 0.05) in the second than in first half (mean ± SEM 7 ± 1 vs. 4 ± 0 m), whereas the mean distance to the off-side line was 2 ± 0 m in both halves. Sprinting performance was lower (p < 0.05) in the first and second 30-m sprint after compared to before the game (0.13 ± 0.04 and 0.07 ± 0.03 s slower, respectively). The present study demonstrates that 1) top-class assistant soccer refereeing is characterized by brief intense bouts of forward and sideways running interspersed with long low activity periods; 2) a top-class assistant referee has a moderate aerobic energy production during the game and episodes of very high anaerobic energy turnover; 3) sprint performance decreases towards the end of a top-level game and this seems to affect the assistant referees' ability to keep up with play.