5A 107 INCREASING WORKLOAD RELATES TO INJURY RISK IN RUNNING 1. INTRODUCTION The yearly occurrence of time-loss injuries in middle-distance runners (64%), longdistance runners (32%), and marathon runners (52%) is high[1]. Most of the injuries are associated with overuse [1], [2]. Injuries lead to a reduced training effort and the inability to compete, which can be detrimental to the career of competitive runners. Therefore, prevention of injuries is important. The Translating Research into Injury Prevention Practice (TRIPP) framework is built on the fact that the professionals only adopt the results of injury research when it helps preventing injuries [3]. The TRIPP framework defines six consecutive steps for research in building the evidence base for the prevention of injuries [3]. The first step within the TRIPP framework is to undertake injury surveillance. The second step is to identify risk and protective factors and injury mechanisms. The third step is to develop preventive measures. The fourth step is creating ideal conditions for scientific evaluation of the preventive measures. The fifth step is the description of the intervention context and development of implementation strategies and the sixth and final step is to implement the intervention in context and evaluate the effectiveness. Despite an extensive body of research on identifying risk factors, to the best of our knowledge, there is the no single study that reveals modifiable risk factors in running enabling the third step of TRIPP: development of preventive measures. In the literature, there is consensus on two nonmodifiable risk factors in runners: (i) a history of running injuries and (ii) an irregular and/or absent menstruation for female runners [4], [5]. For many proposed modifiable risk factors in running, like distance, duration, frequency, pace, interval, weight, and footwear, there is an absence of clear support for an association with injury risk [4], [5]. Although workload and changes in workload are mentioned as modifiable risk factor in runners, and adjustment of the workload may prevent overuse injuries, the results on the relationship between workload as a single nonrelative factor and injuries in running are ambiguous, limited, and even inconsistent [4], [6], [7]. In contrast to the studies on running, a clear relationship between workload and injuries was identified in competitive team sports, such as Australian football [8]–[10], rugby [11], cricket [12], and soccer [13]. These studies found an association between an increase in the relative workload and the risk on sustaining an injury in the same or subsequent week. The relative workload was calculated as a rolling average (RA) of the acute workload in relation to the RA of the chronic workload (acute:chronic ratio). In contrast to the acute:chronic ratio, the acute and chronic workloads in isolation (i.e., not as ratios) was not consistently associated with increased injury risk [11]. Although in literature different time periods are designated as acute and chronic workload, for the acute:chronic ratio most commonly one week of workload (acute
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