The Use of Relative Speed Zones in Australian Football: Are We Really Measuring What We Think We Are?

OBJECTIVES: To examine the difference between absolute and relative workloads, injury likelihood, and the acute:chronic workload ratio (ACWR) in elite Australian football.

DESIGN: Single-cohort, observational study.

METHODS: Forty-five elite Australian football players from 1 club participated. Running workloads of players were tracked using Global Positioning System technology and were categorized using either (1) absolute, predefined speed thresholds or (2) relative, individualized speed thresholds. Players were divided into 3 equal groups based on maximum velocity: (1) faster, (2) moderate, or (3) slower. One- and 4-wk workloads were calculated, along with the ACWR. Injuries were recorded if they were noncontact in nature and resulted in "time loss."

RESULTS: Faster players demonstrated a significant overestimation of very high-speed running (HSR) when compared with their relative thresholds (P = .01; effect size = -0.73). Similarly, slower players demonstrated an underestimation of high-(P = .06; effect size = 0.55) and very-high-speed (P = .01; effect size = 1.16) running when compared with their relative thresholds. For slower players, (1) greater amounts of relative very HSR had a greater risk of injury than less (relative risk [RR] = 8.30; P = .04) and (2) greater absolute high-speed chronic workloads demonstrated an increase in injury likelihood (RR = 2.28; P = .16), whereas greater relative high-speed chronic workloads offered a decrease in injury likelihood (RR = 0.33; P = .11). Faster players with a very-high-speed ACWR of >2.0 had a greater risk of injury than those between 0.49 and 0.99 for both absolute (RR = 10.31; P = .09) and relative (RR = 4.28; P = .13) workloads.

CONCLUSIONS: The individualization of velocity thresholds significantly alters the amount of very HSR performed and should be considered in the prescription of training load.