Association Between Global Positioning System–Based Training Load and Injury Risk in Recreational Runners: A Large Prospective Study

Context: Understanding the relationship between training load and injury in runners may provide information on how to reduce the risk of running injuries. Objective: To investigate the association between training load and injury risk in recreational runners with the use of global positioning system data. Design: Prospective cohort study. Setting: This study is part of a randomized controlled trial on running injury prevention among recreational runners. Runners who provided informed consent received 3 follow-up questionnaires and were requested to share global positioning system data. Patients or Other Participants: Adult runners who registered for running events (distances, 10-42.195 km) in the Netherlands. Main Outcome Measures: Global positioning system-based training load was calculated as the acute : chronic workload ratio (ACWR) based on distance, duration, or speed of each training session. Cox regression models were performed to evaluate the association (hazard ratio [HR]) between the ACWR and running-related injury (RRI) onset. Results: Global positioning system data from 461 participants (72.9% men; mean ± SD age = 43.8 ± 12.4 years; 42.3% reported a new RRI during follow-up) were used for analyses with a total of 20 425 training sessions. A positive association between the ACWR and RRI onset was found for distance (HR = 1.32; 95% CI = 1.00, 1.74) and duration (HR = 1.39; 95% CI = 1.07, 1.79). In the analyses adjusted for confounding variables, only the ACWR based on duration (HR = 1.33; 95% CI = 1.02, 1.74) remained positively associated with RRI onset. No significant association was found between the ACWR and RRI onset when excluding runners with an RRI at baseline (15.8%). Conclusions: We identified an association between the ACWR and RRI onset in runners based on distance and duration respectively. The clinical relevance of the identified associations is questionable given the small HRs and inconsistency in outcomes, which makes the role of general training load advice in the prevention of RRIs uncertain.