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Between-match recovery time, and acute and chronic workloads likely affect subsequent match-injury risk in elite rugby league players.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:chronic workload ratios above 1.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 workloads18.9 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:chronic workload ratios ≥1.6, were 3.4-5.8 times likely to sustain a match injury than players with lower acute:chronic workload ratios (RR range 3.41-5.80 (CI 1.17 to 19.2); likelihood range 96-99%, very likely). Acute:chronic 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).Contrary to the philosophy that high workloads and shorter recovery equate to increased injury risk, our data suggest that high and very-high chronic workloads may protect against match injury following shorter between-match recovery periods. Acute:chronic workload ratios ∼1.5 are associated with a greater risk of match injury than lower acute:chonic workload ratios. Importantly, workloads can be manipulated to decrease the match-injury risk associated with shorter recovery time between matches.

Aim Investigate whether acute workload (1 week total distance) and chronic workload (4-week average acute workload) predict injury in elite rugby league players. Methods Data were collected from 53 elite players over two rugby league seasons. The 'acute:chronic workload ratio' was calculated by dividing acute workload by chronic workload. A value of greater than 1 represented an acute workload greater than chronic workload. All workload data were classified into discrete ranges by z-scores. Results Compared with all other ratios, a very-high acute:chronic workload ratio (2.11) demonstrated the greatest risk of injury in the current week (16.7% injury risk) and subsequent week (11.8% injury risk). High chronic workload (>16 095 m) combined with a veryhigh 2-week average acute:chronic workload ratio (1.54) was associated with the greatest risk of injury (28.6% injury risk). High chronic workload combined with a moderate workload ratio (1.02-1.18) had a smaller risk of injury than low chronic workload combined with several workload ratios (relative risk range from 0.3 to 0.7×/1.4 to 4.4; likelihood range=88-94%, likely). Considering acute and chronic workloads in isolation (ie, not as ratios) did not consistently predict injury risk. Conclusions Higher workloads can have either positive or negative influences on injury risk in elite rugby league players. Specifically, compared with players who have a low chronic workload, players with a high chronic workload are more resistant to injury with moderate-low through moderate-high (0.85-1.35) acute:chronic workload ratios and less resistant to injury when subjected to 'spikes' in acute workload, that is, very-high acute:chronic workload ratios 1.5.