High-speed running and sprinting as an injury risk factor in soccer: Can well-developed physical qualities reduce the risk?

Objectives: This study investigated the association between high-speed running (HSR) and sprint running (SR) and injuries within elite soccer players. The impact of intermittent aerobic fitness as measured by the end speed of the 30-15 intermittent fitness test (30-15 V-IFT) and high chronic workloads (average 21-day) as potential mediators of injury risk were also investigated. Design: Observational Cohort Study. Methods: 37 elite soccer players from one elite squad were involved in a one-season study. Training and game workloads (session-RPE x duration) were recorded in conjunction with external training loads (using global positioning system technology) to measure the HSR (>14.4 km h(-1)) and SR (>19.8 km h-1) distance covered across weekly periods during the season. Lower limb injuries were also recorded. Training load and GPS data were modelled against injury data using logistic regression. Odds ratios (OR) were calculated with 90% confidence intervals based on 21-day chronic training load status (sRPE), aerobic fitness, HSR and SR distance with these reported against a reference group. Results: Players who completed moderate HSR (701-750-m: OR: 0.12, 90%CI: 0.08-0.94) and SR distances (201-350-m: OR: 0.54, 90%CI: 0.41-0.85) were at reduced injury risk compared to low HSR (<= 674-m) and SR (<= 165-m) reference groups. Injury risk was higher for players who experienced large weekly changes in HSR (351-455-m; OR: 3.02; 90%CI: 2.03-5.18) and SR distances (between 75-105-m; OR: 6.12, 90%CI: 4.66-8.29). Players who exerted higher chronic training loads (>= 2584 AU) were at significantly reduced risk of injury when they covered 1-weekly HSR distances of 701-750 m compared to the reference group of <674m (OR = 0.65, 90% CI 0.27-0.89). When intermittent aerobic fitness was considered based on 30-15 V-IFT performance, players with poor aerobic fitness had a greater risk of injury than players with better-developed aerobic fitness. Conclusions: Exposing players to large and rapid increases in HSR and SR distances increased the odds of injury. However, higher chronic training loads (>= 2584 AU) and better intermittent aerobic fitness off-set lower limb injury risk associated with these running distances in elite soccer players. (C) 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.