Many of us regularly work at sporting events: marathons, gran fondos, trail races. Others are runners, cyclists, triathletes. Yet the training we receive on endurance-specific pathologies is often fragmented or absent. Hyponatremia, exercise-associated collapse, cardiac arrest in young athletes: conditions that in the field we recognize less often than we should.
I spoke with Luca Carenzo, anesthesiologist-intensivist at IRCCS Humanitas in Milan, Medical Director of the Milan and Rome marathons, and member of the Expert & Advisory Board of the World Academy for Endurance Medicine.
How did you get from intensive care to marathons?
They're not such distant worlds. Endurance activity exposes the cardiorespiratory, metabolic, and renal systems to conditions of extreme stress that closely resemble critical illness. But as often happens, it all stems from meeting the right people: Federico Ghio from the iHelp team, who manages coverage for the Milan Marathon and was already implementing ECMO support at the advanced medical post ten years ago, and Paolo Emilio Adami, Head of Medical Operations at World Athletics, with whom we brought certification courses to Milan and Rome.
What's the fundamental difference compared to ordinary prehospital care?
In endurance, the context is known and the risk is predictable. In ordinary prehospital care we react to sudden events; in an endurance event, care shifts from response to prevention. But there's another crucial difference: the profile of pathologies is very specific. Being a good prehospital professional isn't enough: dedicated competencies are needed. It's precisely from this need that the Race Emergency Medicine Course of the World Academy for Endurance Medicine was born [1].
What are the most frequent time-dependent pathologies in marathons?
Exertional Heat Stroke is the most significant among life-threatening conditions, and we'll cover it in a dedicated article. Beyond this: cardiac arrest, exercise-associated hyponatremia, exercise-associated collapse. Plus the entire spectrum of classic time-dependent pathologies.
Exercise-associated hyponatremia: how common is it and what mistakes are made?
More common than you think. Symptoms are nonspecific: nausea, headache, confusion, up to seizures. In the field they're easily attributed to fatigue or dehydration. The most frequent error is conceptual: thinking the problem is sodium loss, when it's almost always an excess of free water. Hence the most dangerous operational error: administering more hypotonic fluids. This is why point-of-care sodium measurement is mandatory at World Athletics Label events.
Cardiac arrest in healthy runners: what's the profile?
Asymptomatic subjects, often without known cardiac diagnosis, who collapse during or after exertion [2]. Under 35 years, cardiomyopathies, channelopathies, coronary anomalies prevail. Over 35, silent atherosclerotic coronary disease. In both cases the event is typically arrhythmic, triggered by the interaction between vulnerable substrate and adrenergic trigger.
"Cool first, transport second": how do you explain this to those used to load-and-go?
In heat stroke, effective cooling must begin within 30 minutes. As in ischemic stroke, time is brain. The key point is understanding that the life-saving treatment is not transport, but the intervention in the field [3]. The ambulance doesn't accelerate care: it delays it.
Are these pathologies encountered outside of races too?
Practically all of them. Races don't create special pathologies: they concentrate and make evident conditions present in many other contexts. The worker exposed to heat, the hiker, cardiac events in apparently healthy subjects, exertional rhabdomyolysis. Outside of races the mental frame is often missing: the pathophysiology is the same, but the threshold of suspicion is lower.
If you could change one thing in the training of Italian rescuers?
Structurally incorporate endurance pathologies and heat stress into basic training. Not as an optional module, but as a cross-cutting clinical competency. Heat stroke is time-dependent, early treatment drastically changes prognosis, and it's a non-pharmacological therapy applicable to everyone.
Sources and further reading
- Carenzo L et al. Standardized Emergency Medical Care in Mass Participation Endurance Events: Race Emergency Medicine Course (REMC) Educational Program. Sports Med Open 2025. doi.org/10.1186/s40798-025-00959-x
- Lampert R, Harmon KG. Sudden Cardiac Arrest in Athletes. N Engl J Med. 2026;394(3):268-280. doi:10.1056/NEJMra2312555
- Stomeo N et al. What every intensivist should know about exertional heat stroke. J Crit Care 2025. doi.org/10.1016/j.jcrc.2025.155134
- World Academy for Endurance Medicine
In the next article: a clinical deep dive on Exertional Heat Stroke with Dr. Carenzo.
