Differences Between Relative and Absolute Speed and Metabolic Thresholds in Rugby League.

Purpose: To compare relative and absolute speed and metabolic thresholds for quantifying match output in elite rugby league.

Methods: Twenty-six professional players competing in the National Rugby League were monitored with global positioning systems (GPS) across a rugby-league season. Absolute speed (moderate-intensity running [MIR > 3.6 m/s] and high-intensity running [HIR > 5.2 m/s]) and metabolic (>20 W/kg) thresholds were compared with individualized ventilatory (first [VT] and second [VT]) thresholds estimated from the 30-15 Intermittent Fitness Test (30-15), as well as the metabolic threshold associated with VT (HP), to examine difference in match-play demands.

Results: VT mean values represent 146%, 138%, 167%, and 144% increases in the HIR dose across adjustables, edge forwards, middle forwards, and outside backs, respectively. Distance covered above VT was almost certainly greater (ES range = 0.79-1.03) than absolute thresholds across all positions. Trivial to small differences were observed between VT and MIR, while small to moderate differences were reported between HP and HP.

Conclusions: These results reveal that the speed at which players begin to run at higher intensities depends on individual capacities and attributes. As such, using absolute HIR speed thresholds underestimates the physical HIR load. Moreover, absolute MIR and high metabolic thresholds may over- or underestimate the work undertaken above these thresholds depending on the respective fitness of the individual. Therefore, using relative thresholds enables better prescription and monitoring of external training loads based on measured individual physical capacities.