ProjectRun21: Do running experience and running pace influence the risk of running injury-A 14-week prospective cohort study.

OBJECTIVES: The health benefits from participation in half-marathon is challenged by a yearly running-related injury (RRI) incidence proportion exceeding 30%. Research in injury etiology is needed to successfully prevent injuries. The body's load capacity is believed to play an essential role for injury development. Therefore, the purpose of ProjectRun21 was to investigate the association between load capacity defined as running experience and running pace, and RRI when following a specific half-marathon running schedule. DESIGN: A 14-week prospective cohort study. METHODS: A cohort of 784 healthy runners followed a specific half-marathon running schedule. Data on running activity was collected objectively using a Global-Positioning-System watch or smartphone. RRI were collected using e-mail-based weekly questionnaires. Primary exposures were running experience and running pace, dichotomized into a high and a low group for runners running less or more than 15km/week and faster or slower than 6min/km, respectively. Data was analyses through time-to-event models with cumulative risk difference (RD) as measure of association. RESULTS: A total of 136 participants sustained a RRI during follow-up. Although not statistically significant, all estimates indicate a tendency toward fewer injuries amongst runners categorized as having high experience (RD=-11.3% (-27.2% to 4.6%)) or high pace (RD=-17.4% (-39.0% to 4.5%)), and a combination of both high experience and high pace (RD=-8.1% (-22.3% to 6.1%)) compared with their counterpart peers. CONCLUSIONS: Runners covering less than 15km per week, and/or runs slower than 6min/km, may sustain more RRI than their counterpart runners.