Runners with a high body mass index and previous running-related problems is a high-risk population for sustaining a new running-related injury: A 18-month cohort study.

High body mass index (BMI) and a previous running-related injury (RRI) have been highlighted as two risk factors for sustaining an RRI. However, a critical gap exists in the knowledge of whether runners with both elevated BMI and a previous RRI constitute a particularly vulnerable subgroup in terms of susceptibility to new RRIs. Therefore, the present study aimed to evaluate if those with high BMI and a concomitant history of running-related problems in the past 3 months were more prone to sustain a new RRI compared with runners with normal BMI and without previous running-related problems. This study was part of the "Garmin-RUNSAFE Running Health Study," an 18-month cohort study. The runners completed a baseline questionnaire containing questions regarding demographic data and previous running-related problems and were asked to continuously track their running activities. The exposure were dichotomized into "no previous running-related problem" or "previous running-related problem," and each group was further categorized into four subgroups depending on BMI. Time-to-event analysis was used to estimate the cumulative incidence risk difference (cIRD). The results highlight those with a BMI >30 kg/m with a previous running-related problem to face the highest injury risk of 71%, whereas those with a BMI between 19 and 25 kg/m without a previous running-related problem had the lowest injury risk of 43% corresponding to a cIRD of 28% [95% CI: 19%; 36%]. This result highlights those with high BMI and previous running-related problems as a high-risk subpopulation that would benefit from interventions of preventing running-related injuries.