Background Although the number of individuals who enjoy sports every day is increasing owing to growing health consciousness, marathons pose health risks and can cause various types of health damage, including cardiac arrest. Furthermore, it is important to establish a system for predicting dangers and providing medical care in advance, including securing routes for transporting individuals in need of medical care during mass-gathering events.

Objective This study aimed to investigate cases requiring medical care that occurred since the introduction of the full marathon at the Yokohama Citizen’s Marathon in 2015 and to examine the medical care system and its safety in relation to efforts to build a safer medical system for large-scale marathon races.

Methods We retrospectively examined the incidence of health disorders and cardiac arrest during the Yokohama marathon race using the medical records provided by our committee from 2015 to 2024. Additionally, we retrospectively examined the changes in the medical support system.

Results The total number of participants in the full marathon was 134,946 (total number of runners, 147,861), while the number of medical staff was 4,669 (total number of runners, 3.1±0.4%). There were 136 cases of emergency transport (0.1%), of which 27 required hospitalization (0.02%), and 3 cases of cardiac arrest during the competition (0.002%). All patients were quickly resuscitated on-site with cardiopulmonary resuscitation, and no deaths occurred. The patient presentation ratio (PPR), which represents the number of injuries and sickness per 1,000 runners, was 14.76 (range, 11.1–17.7), and the transport-to-hospital ratio (TTHR), which represents the number of emergency transports per 1,000 runners, was 0.96 (range, 0.4–2.1).

Discussion Although the number of emergency transports increased and decreased owing to changes in the timing of the event and changes in temperature, it was possible to provide faster and more appropriate medical care to those in need of medical assistance. Analyzing these results annually and reviewing countermeasures to improve the medical support manual will lead to safer marathons. Such efforts will directly lead to a reduction in the number of emergency transports. In fact, the PPR was significantly lower in the current study than that in previous studies, while the TTHR was lower or similar to that in a previous study.

Conclusion The Yokohama marathon is one of the largest marathons in Japan, and this study identified some participants requiring care on-course every year. Analysis of annual injury data has enabled better prediction and response to injuries, leading to safer marathon events. Most medical complaints were minor illness caused by dehydration or musculoskeletal in nature; however, there were life-threatening conditions such as CA that highlight the need for detailed planning, multi-disciplined coordination, and communication to ensure a safe and secure event. More detailed analysis of past race data under various environmental conditions is essential for running a safer large-scale citizen marathon, and the establishment of “All Yokohama” medical support system that includes local medical institutions, volunteer staff, fire departments, police, and medical staff contributes to running a safer citizen marathon.

The authors have declared no competing interest.

This study did not receive any funding

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Yokohama City University Hospital, Public University Corporation Medical and Hospital Management Department, Clinical Research Promotion Division, Ethics Office (1-1-1 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-0004, Japan). After checking against internationally established research ethics guidelines, the judgement was determined that the study does not constitute "life science/medical research involving human subjects."

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