What should you do in the first minutes of a suspected heat stroke case on trail?

Stop the runner from continuing, move them to shade if any is available, and remove pack, vest, and excess clothing to expose skin. Begin cooling with whatever is on hand immediately, and radio ahead so the nearest aid station or medical point can prepare cold water immersion before the runner arrives if evacuation is needed.

Why does cold water immersion work better than wet towels or ice packs on trail?

Whole-body cold water immersion can cool at up to 0.35 degrees Celsius per minute, according to Casa et al. 2007. Wet towels, ice packs, ice sheets, fans, and misting, the methods most easily carried on a remote course, only achieve roughly 0.03 to 0.08 degrees Celsius per minute. Above 0.15 degrees Celsius per minute is considered adequate cooling, which is why aid stations with immersion capability change outcomes on long evacuation routes.

What water temperature and immersion duration should be used on a trail race?

Use the coldest water available at the aid station, ideally 2 to 15 degrees Celsius, with ice added if stocked. Immerse the whole body, shoulders and scalp included, with the airway kept clear. Monitor rectal temperature every 5 minutes and maintain immersion until it falls below 38.6 degrees Celsius before considering evacuation.

When and how should EMS or evacuation be coordinated for a trail heat stroke case?

Call for evacuation support the moment heat stroke is suspected, in parallel with starting cooling on-site, not after. This is the Cool First, Transport Second doctrine: cooling begins immediately with the aid station's own equipment while evacuation is organized, since transport time on trail terrain can be long and cooling cannot wait for it.

How do remote aid stations handle heat stroke when evacuation takes a long time?

Remote aid stations need their own cold water immersion capability rather than relying solely on the finish-line medical tent, since evacuation from mid-course sections can take well over an hour on foot or by vehicle. A folding, transportable cooling tub that a small aid station crew can set up and that stays stable on uneven trail ground is what makes on-site cooling realistic that far from the finish.

How to Manage a Heat Stroke Case While Trail Running: FAQ and Immediate Steps

Q: How do you recognize a heat stroke case on a trail running course?

Early signs include a runner falling behind their expected pace, stumbling on easy terrain, becoming disoriented, or giving confused answers at an aid station. Critical signs are loss of consciousness, seizure, and a stop in sweating despite hot skin. On remote sections, aid station staff and sweepers are often the first to notice these signs, sometimes far from the nearest medical post.

Trail running adds two variables that road races rarely face: aid stations can be far from the finish, and evacuation from mid-course sections can take much longer than a road ambulance run. That combination means cooling decisions on trail cannot wait for transport. Here are direct answers to the questions race medical directors and aid station crews ask most.

How do you recognize a heat stroke case?

Watch for a runner falling well off their expected pace, stumbling on terrain they should handle easily, or giving confused, slow answers at an aid station check-in. The critical signs are loss of consciousness, seizure, and a stop in sweating despite hot skin. On remote sections, sweepers and aid station volunteers are often the only people positioned to catch these signs before they become a full collapse.

What do you do in the first minutes?

Stop the runner from continuing and move them to shade if any exists on the course.
Remove pack, vest, and excess clothing to expose as much skin as possible.
Start cooling with whatever is on hand immediately, and radio ahead so the next aid station can have cold water immersion ready before the runner arrives, if evacuation is required.

Why does cold water immersion beat wet towels or ice packs?

Whole-body cold water immersion reaches up to 0.35°C per minute (Casa et al., Exercise and Sport Sciences Reviews, 2007). Wet towels, ice packs, ice sheets, fans, and misting, the tools most easily carried to a remote aid station, only manage about 0.03 to 0.08°C per minute. Above 0.15°C per minute is considered adequate cooling. On a course where evacuation might take an hour or more, that gap between immersion and surface cooling is the difference between a stabilized runner and a deteriorating one.

What water temperature and how long should immersion last?

Use the coldest water an aid station can stock, roughly 2 to 15°C (36 to 59°F), with ice added when available. Immerse shoulders and scalp with the airway kept clear by staff. Check rectal temperature every 5 minutes and maintain immersion until it drops below 38.6°C before considering any move toward evacuation.

When and how do you coordinate evacuation?

Apply the "Cool First, Transport Second" doctrine (ACSM 2023, IOC/BJSM 2021, Korey Stringer Institute): call for evacuation the moment heat stroke is suspected, at the same time cooling starts, not after it. On trail terrain, transport time is the unpredictable variable, so cooling has to begin with whatever equipment is already at the aid station rather than waiting for a vehicle or helicopter to arrive.

How do remote aid stations manage this when evacuation is far away?

Aid stations positioned deep in the course need their own immersion capability rather than depending on the finish-line medical tent. A tub that folds for transport, sets up quickly, and stays stable on uneven trail ground even under load is what makes it realistic for a small volunteer crew to run cooling far from the finish. Deployment time is a secondary detail once that stability and setup practicality are covered, and it should always be described as under 5 minutes, never tied to how many people are running the station.

Can a runner go back to the race after they seem to recover?

No. Every suspected case requires medical evaluation and, in most cases, transport, even if the runner looks fine after cooling at the aid station. Rhabdomyolysis, acute kidney injury, and coagulopathy can appear hours later, so a runner should never be waved back onto the course after a suspected episode.