Chronic disease, allergies, and increased years of running are risk factors predicting gradual onset running-related injuries in ultramarathon runners—SAFER XIX study in 29 585 race entrants

Abstract

OBJECTIVES : To identify risk factors that predict gradual onset running-related injuries (GORRIs) in ultramarathon runners entering a mass community-based event. DESIGN : Descriptive cross-sectional study. SETTING : Two Oceans 56 km ultramarathon 2012 to 2015. PARTICIPANTS : Race entrants (n = 42 003) completed a compulsory pre-race medical history questionnaire; 29 585 (70.4%) of entrants consented. DEPENDENT/OUTCOME VARIABLE : A history of GORRIs in the past 12 months among race entrants. MAIN OUTCOME MEASURES : In a multi-variate model, runner demographics, training variables (years of recreational running, weekly running distance, training running speed), history of chronic disease (composite score), and history of allergies were included as factors predicting GORRIs. Prevalence (%) and prevalence ratios (PR, 95% CIs) are reported. RESULTS : The lifetime prevalence of GORRIs in ultramarathon runners was 24.4%. Independent factors predicting GORRIs were: higher chronic disease composite score (PR = 2.05 times increase risk for every 2 additional chronic diseases; P < 0.0001), history of allergies (PR = 1.66; P < 0.0001), increased years of recreational running (PR = 1.07 times increased risk for every 5 year increase in running; P < 0.0001), lower average weekly running distance (PR = 0.98 times decreased risk for every 15 km increase weekly running distance; P < 0.0001), and slower average training running speed (PR = 0.96 times decreased risk for every km/h increase in training running speed; P < 0.0001). CONCLUSIONS : Novel risk factors predicting GORRIs are increased number of chronic diseases and a history of allergies. These factors, together with training variables (years of recreational running, weekly running distance, and training running speed) can be targeted to develop and implement injury prevention, treatment, and rehabilitation interventions in ultramarathon runners.