Medical Support at Ultramarathons — EMTs, Medic Tents, IV Fluids, and What Happens When Things Go Wrong

Running 100 Miles Through the Night Is Not Without Risk

The premise of an ultramarathon is that the human body can be pushed far beyond what most people consider its limits — and that doing so safely is a solvable logistics problem. Race directors take that second part seriously. Every permitted 100-mile race operates a parallel medical infrastructure alongside the athletic competition, designed to catch problems before they become emergencies and to manage emergencies when they occur.

What that infrastructure looks like depends on the race, the terrain, and the size of the field. A 200-person mountain race in a remote location runs a different medical operation than a 1,000-person desert race on accessible trails. But the categories of support are consistent across the sport.

Medics at Aid Stations

Major aid stations — particularly the larger crew-accessible stations at key mileage points — have medical personnel on site. These are typically emergency medical technicians (EMTs), wilderness first responders (WFRs), or registered nurses, often volunteering. Some high-profile races bring in sports medicine physicians.

At a well-staffed station, the medical area is physically separate from the food and crew area. A runner in distress gets directed there immediately. Personnel at the medical station can assess vital signs, treat blisters and musculoskeletal injuries, administer IV fluids where permitted and appropriate, monitor for the major medical emergencies that occur in endurance events, and make the call to pull a runner from the race if necessary.

Not every station has dedicated medical staff. Smaller checkpoints may have trained volunteers capable of basic assessment with a protocol for calling for evacuation. The race guide typically identifies which stations have medical personnel.

Roving Medical Support on Course

For races covering remote terrain, most race organizations deploy roving medical personnel — either on foot, on bikes, on ATVs, or in vehicles depending on the course — who sweep sections of the course throughout the event. These roving medics handle runners who encounter problems between stations.

The sweep team — the final group of personnel moving through the course after the last runner — are typically required to have medical training and carry basic emergency supplies. Their job is to ensure no runner is left on course without assistance.

The Main Medical Emergencies in Ultra Running

Hyponatremia is overhydration causing dangerously low sodium levels. It is counterintuitive — most people assume dehydration is the danger — but drinking too much plain water over many hours dilutes blood sodium to dangerous levels. Symptoms include nausea, headache, disorientation, confusion, swelling in the hands and face, and in severe cases seizures and loss of consciousness. It is one of the most common serious medical events in long ultra races, particularly in hot conditions where runners are encouraged to drink frequently.

Treatment is electrolyte replacement and stopping water consumption, not giving more water. Medical personnel trained in ultra running are specifically looking for this.

Hypothermia is the loss of core body temperature, most common in mountain races during night sections when temperature drops significantly. A runner who slows down dramatically loses the body heat generated by movement. Wet conditions accelerate it. Signs include shivering, slurred speech, poor decision-making, and confusion. Treatment at an aid station involves removing wet clothing, adding insulation, providing warm fluids, and in serious cases, evacuation.

Rhabdomyolysis is the breakdown of muscle tissue releasing proteins into the bloodstream that damage the kidneys. It occurs in extreme efforts, particularly with inadequate hydration. Dark or cola-colored urine is the primary warning sign. Runners who report this to medical staff are typically pulled immediately.

Dehydration and heat exhaustion are the more common and better-understood problems. Aid station medical staff manage these with fluids, shade, cooling, and rest. Heat stroke — the serious escalation with confusion and loss of sweating — requires rapid cooling and evacuation.

Severe blisters and foot damage are not life-threatening but can end a race. Medical personnel at aid stations perform blister drainage, taping, and dressing. Some runners arrive at major stations requiring 20 minutes of foot work before continuing.

IV Fluids

Whether medics can administer IV fluids varies by jurisdiction, race permits, and the certification level of the medical staff. Many races permit this. At stations where IV access is available, a runner who is severely nauseated and unable to keep fluids down may receive a bag of saline to restore fluid balance and continue racing.

Some race organizations actively discourage IV use except in genuine emergencies, concerned about runners using IVs as a performance shortcut rather than a medical intervention.

When a Runner Is Pulled from the Race (DNF)

A DNF — Did Not Finish — is sometimes a voluntary decision and sometimes a forced one. Medical personnel have the authority to pull a runner from the race if they determine the runner cannot safely continue. This determination is not a suggestion. A runner who is disoriented, showing signs of hyponatremia, or hypothermic does not get to vote on whether they keep going.

The process typically involves the medic completing documentation, the runner receiving a wristband or tag marking them as DNF, and arrangements being made for transport to the finish area or a vehicle. The runner’s bib or tracker is collected.

Forced DNFs are uncommon but occur at every large race. The runners who fight them hardest are often the ones who most need them.

Ambulances and Evacuation

Major races have ambulance or helicopter evacuation protocols for runners who cannot be treated on course and need hospital care. This is rare but planned for. In remote terrain, the evacuation plan may involve a combination of carry-out on a stretcher, ATV transport to a vehicle-accessible point, and then ambulance.

Race directors are required to file evacuation plans as part of their permitting process. Land management agencies — the Forest Service, Bureau of Land Management, National Park Service — review these plans and may require specific emergency infrastructure as a condition of the permit.

The Honest Safety Picture

Ultramarathons have a remarkably good safety record relative to the physical demands involved. Deaths occur in the sport and are taken seriously, but they are rare at permitted races with functioning medical infrastructure. The danger in the sport is real — remote terrain, extreme weather, extreme physical demands — but the medical systems that have developed around it are sophisticated and run by people who take them seriously.

The practical answer for a runner considering a first ultra: the race has thought about what could go wrong and built a system around it. That system is not infallible, but it exists, it is staffed, and the people running it are there because they care about the outcome.

Related: Aid Stations at Ultramarathons — What to Expect | What Happens If a Runner Gets Lost? | Should I Run an Ultramarathon?