Low Chronic Workload and the Acute Workload Ratio Are More Predictive of Injury Than Between-Match Recovery Time: A Two-Season Prospective Cohort Study in Elite Rugby League Players

Hulin, B. T.; Gabbett, T. J.; Caputi, P.; Lawson, D. W.; Sampson, J. A.

Background: Between-match recovery time and acute and chronic workloads likely affect subsequent match-injury risk in elite rugby league players.

Methods: Workloads of 28 players throughout two seasons were calculated during short (<7 days) and long (≥7 days) between-match recovery times. ‘Acute’ workloads (1 week) greater than ‘chronic’ workloads (4-week rolling average acute workload) resulted in acute workload ratios above 1. Results: No difference was found between the match-injury risk of short and long between-match recovery periods (7.5±2.5% vs 6.8±2.5%). When players had a short recovery between matches, high chronic workloads (18.9–22.0 km) were associated with a smaller risk of match injury than chronic workloads <18.9 km (relative risk (RR) range 0.27–0.32 (CI 0.08 to 0.92); likelihood range 90–95%, likely). Players who had shorter recovery and acute workload ratios ≥1.6 were 3.4–5.8 times more likely to sustain a match injury than players with lower acute workload ratios (RR range 3.41–5.80 (CI 1.17 to 19.2); likelihood range 96–99%, very likely). Acute workload ratios between 1.2 and 1.6 during short between-match recovery times demonstrated a greater risk of match injury than ratios between 1.0 and 1.2 (RR=2.88 (CI 0.97 to 8.55); likelihood=92%, likely). Conclusions: Contrary to the philosophy that high workloads and shorter recovery equate to increased injury risk, the data suggest that high and very-high chronic workloads may protect against match injury following shorter between-match recovery periods. Acute workload ratios ∼1.5 are associated with a greater risk of match injury than lower acute workload ratios. Importantly, workloads can be manipulated to decrease the match-injury risk associated with shorter recovery time between matches.

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