Why do workload spikes cause injuries, and which athletes are at higher risk? Mediators and moderators in workload–injury investigations

Spikes in training and competition workloads, especially in undertrained athletes, increase injury risk.1 However, just as attributing athletic injuries to single risk factors is an oversimplification of the injury process,2 3 interpreting this workload-injury relationship should not be done in isolation. Instead, we must further unpack how (ie, through which mechanisms) workload spikes might result in injury, and what characteristics make athletes more robust or more susceptible to injury at any given workload. In other words, which factors mediate the workload-injury relationship, and which moderate the relationship. Like dominoes being knocked over, mediators can be viewed as the intermediary steps that explain the association between an observed variable and an outcome.4 In this context, mediating variables help to explain ‘why changes in workloads might cause injuries?’ For example, it is known that rugby league players exposed to spikes in running workloads, indicated by a high acute:chronic workload ratio, are at an increased risk for non-contact injuries.5 One potential explanation is that neuromuscular fatigue mediates this relationship, such that increased …