Medical complications and deaths in 21 and 56 km road race runners: a 4-year prospective study in 65 865 runners--SAFER study I.

BACKGROUND Cardiac arrest and sudden death during distance-running events have been reported but other medical complications, including serious life-threatening complications have not been well described. OBJECTIVE To document the incidence and nature of medical complications during 21 and 56 km running races. DESIGN Prospective study. SETTING Two Oceans Marathon races (21 and 56 km races). PARTICIPANTS 65 865 race starters (39 511-21 km runners, 26 354-56 km runners). METHODS Medical complications (defined as any runner requiring assessment by a doctor at the race medical facility or a local hospital on race day) were recorded in each of the 4 years of the study period. Complications were further subdivided into serious (potentially life-threatening) complications and deaths and were also analysed by system and final diagnosis. RESULTS In the 4 years, 545 medical complications were recorded, resulting in an overall incidence (per 1000 race starters) of 8.27. The incidence of serious (potentially life-threatening) medical complications was 0.56 (37 serious complications). Two deaths occurred in 21 km runners (incidence of 0.05). The most common specific medical complications were exercise-associated collapse (postural hypotension), dermatological conditions, musculoskeletal injuries and serious exercise-associated muscle cramping. CONCLUSIONS The incidence of medical complications was higher in 56 km runners but sudden cardiac deaths only occurred in 21 km runners. Serious medical complications were as common in 21 km as in 56 km runners. Risk factors for medical complications need to be determined in 21 and 56 km runners to plan strategies to reduce the risk of adverse medical events in endurance runners.