One of the best predictors of injury risk among athletes are abrupt increases in training load. These are typically observed during periods of concentrated loading such as preseason training camps where practices are often held twice daily. Other times where this may occur are following breaks or unloading weeks where the coaches crank up training intensity during the first week back. As it turns out, the acute workload relative to the chronic workload appears to be a useful ratio in predicting injury rates. While the acute to chronic training load ratio alone appears to be useful for monitoring and managing athlete workloads, it is unclear what role fitness plays in this model. Typically, one with higher fitness can withstand increased workloads better than less-fit individuals. Presumably their risk of injury would be lower despite increased workloads.
A new study published ahead of print in the Journal of Science and Medicine in Sport assessed the relationship between perceived training load markers and injury risk among elite professional soccer players. The sample was comprised of 48 players whom were monitored throughout an entire preparatory and competitive season. The Yo-Yo intermittent recovery test was administered to determine the players’ fitness levels. Weekly totals for sRPE were used to calculate the acute (i.e., weekly load) to chronic (i.e., 4-week rolling average load). Odds of injury risk were then determined based on if the athlete was considered high-fit versus low fit.
The findings showed that athletes experiencing loads >1500 au were significantly more likely to experience injury than athletes experiencing loads <1500 au (OR = 1.95). As would be expected, athletes who were classified as higher-fit tolerated increases in training load better than lower-fit athletes, of which were more likely to experience injury (OR = 4.52). Finally, athletes who maintained acute to chronic workload ratios of between 1.0-1.25 were at a significantly lower risk of injury (OR = 0.68) than athletes who had lower acute to chronic training load ratios (<0.85). The authors conclude that high aerobic fitness along with moderate workloads that fluctuate only moderately appear to be protective against injury in professional soccer players.
Malone, S. et al. The acute:chonic workload ratio in relation to injury risk in professional Soccer. Journal of Science and Medicine in Sport. Ahead of print.