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Emergency Triage of Collapsed Endurance Athletes

A Stepwise Approach to On-Site Treatment

LTC Fred H. Brennan, Jr, DO; COL Francis G. O'Connor, MD


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In Brief: Physicians providing medical coverage at endurance events know that athletes often collapse during the race or shortly after crossing the finish line. An athlete who collapses during a race may have an ominous condition, such as a cardiac or neurologic event. The most common reason that athletes collapse at or shortly after the finish line is exercise-associated collapse, a benign postural hypotensive episode that resolves with rest, oral fluids, and elevation of the lower extremities. Volunteer clinicians at races must be able to quickly determine the cause of collapse and take appropriate steps to ensure that athletes receive proper initial care.

Family physicians are often asked to provide medical coverage for mass-participation endurance events. Most athletes who come to race aid stations or the finish line medical tent need little more than basic first aid for blisters, cramps, strains, and nausea. However, when athletes collapse during a race, clinicians must be aware that a more serious underlying medical condition potentially exists.

Exercise-associated collapse (EAC) is the most common reason that endurance athletes collapse at or shortly after crossing the finish line.1-5 EAC is generally a benign condition caused by inadequate vasoconstriction in the extremities when exercise abruptly ceases. The condition resolves with rest, oral fluids, and elevation of the lower extremities.

An athlete who collapses during an event, however, presents a more worrisome scenario and often has a more serious medical issue, such as a cardiac, metabolic, or neurologic condition.2,3 Race physicians who employ a systematic approach for managing collapsed athletes can properly triage patients to ensure timely and appropriate care. Using guidelines and algorithms for triage, management, and practical decision-making can help race-day physicians deliver the best possible care.


Published epidemiologic studies from mass participation events demonstrate several consistent findings. The number of visits to race medical tents can be quite high and directly correlates with the distance of the event and the environmental temperatures during the race.1,3 The number of athletic casualties substantially increases in longer events and hotter weather. Review of current data reveals that EAC, heat illness, and muscle cramps are the most common reasons for visits to endurance-event medical tents.1-5

Studies1,3 of medical data about casualties at endurance events confirm anecdotal observations that athletes who collapse on the race course typically have more serious, potentially life-threatening medical conditions. Those who collapse at the finish line or shortly thereafter tend to have EAC (table 1).

TABLE 1. Conditions Associated With Collapse
During or After Prolonged Exercise
Cardiac arrest
Exercise-associated collapse
Muscle cramps
Orthopedic conditions
Other medical conditions

Adapted with permission from O'Connor F, Pyne S, Brennan FH Jr, et al: Exercise-associated collapse: an algorithmic approach to race day management. Am J Med Sports 2003;5(3):213 © Le Jacq Communications, Inc.

Maron et al6 reviewed the risk of sudden cardiac death associated with running marathons at the Marine Corps Marathon and the Twin Cities Marathon. They concluded that the risk of sudden cardiac death in marathon runners is quite small (1 in 50,000) and probably less than initially anticipated; however, medical volunteers must be prepared to manage a sudden cardiac event in a runner or a spectator on the course.

Collapse During an Endurance Event

When a medical volunteer sees a collapsed athlete on the course, he or she must anticipate the worst-case scenario and act quickly to determine the cause. The physician must consider cardiac causes (eg, lethal arrhythmias, ischemia, myocardial infarction, aortic dissection, ruptured aortic aneurysm), metabolic emergencies (eg, symptomatic hyponatremia, hypoglycemia), and neurologic conditions (eg, cerebrovascular accident, subarachnoid bleeding, seizure).

Extremes of body temperature (ie, hyperthermia or hypothermia) can be life threatening and must be managed immediately. A collapsed athlete who is gasping for air may be having an extreme asthma exacerbation or an anaphylactic reaction, or may have aspirated a foreign body, such as a chunk of a sports bar. Severe cramping and other orthopedic conditions, such as stress fracture, can also cause an athlete to collapse. Physicians positioned along the race course must be prepared to triage and initially stabilize any of these conditions until further assistance arrives at the scene.

Finish Line and Postrace Collapse

At the finish line, athletes who have EAC are unable to stand or walk unaided because of lightheadedness, faintness, dizziness, or syncope. These athletes typically recover quickly with minimal intervention. Roberts2 classified collapse based on core body temperature and overall clinical severity (table 2), a helpful tool for triaging the collapsed athlete. EAC excludes orthopedic injuries that may prevent a racer from completing the event.1-3

TABLE 2. Classification of a Collapsed Athlete by Thermal Status and Severity

Thermal State   MildModerateSevere
HyperthermicTemp ≥ 39.4°C (103°F);   
CNS normal; walks with
or without assistance
Temp ≥ 40.5°C (105°F);
CNS normal; or no oral intake;
or extra fluid loss; or unable
to walk; or severe muscle spasm

Temp ≥ 41.1°C (106°F);
CNS changes

Probable heatstroke
NormothermicTemp 36.1°-39.4°C
(97°-103°F);CNS normal;
walks with or without
Temp 36.1°-39.4°C (97°-103°F);
CNS normal; or no oral intake;
or extra fluid loss; or unable
to walk; or severe muscle spasm   
Temp 36.1°-39.4°C
(97°-103°F); CNS changes

Probable hyponatremia
(confirm sodium and glucose levels)

HypothermicTemp ≤ 36.1°C (97°F);
CNS normal; walks with
or without assistance
Temp ≤ 35°C (95°F);
CNS normal; or no oral intake;
or extra fluid loss; or unable
to walk; or severe muscle spasm
Temp ≤ 32.2°C (90°F);
CNS changes

Profound hypothermia
Temp = core body temperature; CNS = central nervous system

Adapted with permission from Roberts WO: Exercise-associated collapse in endurance events: a classification system. Phys Sportsmed 1989;17(5):50

The pathophysiology of EAC is not completely elucidated and is probably multifactorial. Interestingly, biochemical analysis of collapsed athletes versus control athletes failed to demonstrate significant differences in dehydration, suggesting that the mechanism of collapse is not fluid loss or inadequate fluid intake.1 EAC appears to result from an inadequate or impaired vasoconstrictive response that leads to subsequent venous pooling, hypotension, and then collapse.7 All of the serious medical conditions that more commonly occur during the race can also occur at the finish line and postfinish area; therefore, the same systematic initial approach should be taken—no matter when or where the collapse occurs.

The Triage Process

All distressed athletes, whether their problems appear life threatening or not, should be directed into the medical tent. The role of the physician in the medical tent is to quickly assess the clinical situation and determine the severity (table 3 and figure 1). An experienced clinician can be designated as the triage officer responsible for the rapid assessment of incoming athletes. The triage process is initiated as the athlete is assisted or carried into the medical tent. The initial evaluation or primary survey begins with the ABCs: A = an open, secure airway; B = breathing pattern (normal, not breathing, or distressed); C = circulation and assessment of pulse rate and pulse quality. If any of the ABCs are compromised, the athlete is immediately triaged as "severe" and treated per the Advanced Cardiac Life Support (ACLS) guidelines. Symptoms of chest pain, dyspnea, or severe headache should also be considered serious and evaluated expeditiously.

TABLE 3. Signs Indicating the Severity of the Collapsed Athlete's Condition

Immediate AssessmentSevere ConditionNonsevere Condition
Mental state
Core temperature
Systolic blood pressure
Heart rate
Unconscious or altered
Confused, disoriented, aggressive
>40°C (104°F)
<100 mm Hg
<40°C (104°F)
>100 mm Hg
Additional AssessmentSevere ConditionNonsevere Condition
Blood glucose
Body weight gain or loss
<60 or >120 mg/dL
<135 or >148 mmol/L
60-120 mg/dL
135-148 mmol/L
Reprinted with permission from O'Connor F, Pyne S, Brennan FH Jr, et al: Exercise-associated collapse: an algorithmic approach to race day management. Am J Med Sports 2003;5(3):215. © Le Jacq Communications, Inc.

Next, the athlete's level of consciousness and overall mental status is determined. A confused, disoriented, or unconscious athlete should be categorized as severe and triaged accordingly. If evidence of head or facial trauma is seen, a cervical spine injury should be assumed until proven otherwise.

Athletes with less worrisome symptoms can be seen in a timely, nonurgent manner. Athletes should lie down on cots and have their lower extremities and pelvis elevated above their hearts. The initial vital signs are then taken to complete the primary survey. An athlete who has a simple episode of EAC will tend to improve rapidly in the head-down position and typically does not require an extensive evaluation.

For more serious conditions, the secondary survey begins with a more thorough history and physical examination. It is important, but often forgotten, to look at the race bib and/or the medic alert medal for important medical information. Medical and surgical history should be obtained, if possible. Prodromal symptoms such as palpitations, severe headache, chest pain, wheezing, or itching should be noted and will clue the clinician to the possible cause (eg, arrhythmia, subarachnoid bleeding, cardiac ischemia, asthma, anaphylaxis). Current medications, recent use of ergogenic aids, fluid and "fuel" sources used during the race, recent or ongoing medical conditions, recent vomiting, diarrhea, and urinary output during the race are critical historical points. Nausea and vomiting may be a sign of overhydration and hyponatremia. A positive family history for sudden cardiac death in an athlete who has a true syncopal episode on the course should raise suspicion for a cardiac cause (eg, long QT syndrome, hypertrophic cardiomyopathy, arrhythmogenic right ventricular dysplasia).

A focused physical exam is necessary to exclude serious medical conditions. A general assessment of mental status, hydration (ie, skin turgor, dry mouth), and skin (ie, pale, flushed, clammy, or dry) can be helpful. Vital signs should again be recorded and regularly monitored. A cardiopulmonary exam focusing on significant murmurs, irregular heartbeat, wheezing, unilateral breath sounds, and rales will help eliminate serious cardiac or pulmonary disorders from the differential diagnosis. Sustained or marked abnormality in speech, mental status, or gait should provoke a thorough neurologic examination and evacuation.

Treating the Collapsed Athlete

Upon completion of the primary and secondary survey, the collapsed athlete can be further assessed and treated. Based on the vital signs and mental status, the EAC algorithm (figure 2) may be used as a management tool.

Normal vital signs and mental status. At the finish line, the athlete appears weak and requires almost immediate assistance with walking. Despite assistance, most runners collapse and many require stretcher transport to the medical tent. They may be disoriented but rapidly improve when they lie down with their legs and pelvis elevated. Oral hydration is encouraged in the absence of nausea and vomiting. Any abnormality in blood pressure or pulse also rapidly corrects itself within 15 to 30 minutes of rest and leg elevation.

If the remainder of the physical exam is normal and the athlete is without further focused complaints, he or she may be safely discharged with basic instructions on when to seek further medical attention. Athletes who have severe muscle cramps or orthopedic injuries will typically arrive with normal vital signs or perhaps mild tachycardia caused by pain. Intravenous (IV) fluids are unnecessary and discouraged (table 4).

TABLE 4. Considerations for Initiating Intravenous (IV) Therapy

Consider IV Access if Patient Has
Obvious signs of dehydration (sunken eyes, parched lips and tongue, poor skin turgor)
Persistent tachycardia (heart rate >100/min)
Persistent hypotension (systolic blood pressure <110 mm Hg)

Initiate IV Access if Patient Has
Hemodynamic instability (symptomatic tachycardic or bradycardic arrhythmia)
Arrhythmia or cardiac ischemia on electrocardiogram

Hyperthermia or hypothermia. Athletes who are hyper- or hypothermic but have normal mental activity should be cooled or warmed accordingly. If clinical signs of hyper- or hypothermia are present, a rectal temperature should be obtained and recorded. As long as the athlete's vital signs are stable, mildly hyperthermic athletes may be cooled by removing excess clothing and having them rest in a cool, shady place. An ice pack wrapped in a wet towel may also be applied to the neck, axilla, or groin.2

Mildly hypothermic athletes (ie, rectal temperature 35°-37°C, [95°-97°F]) may be passively rewarmed by removing wet clothing, applying a blanket or space blanket, and having them rest in a warm area of the medical tent. IV fluids are unnecessary unless the athlete appears obviously dehydrated, has persistent tachycardia (heart rate greater than 100/min), or has persistent hypotension (systolic blood pressure less than 110 mm Hg).1,3

When the athlete is normothermic and clinically stable, he or she may safely leave the medical tent. Continuing to race after leaving the tent is not recommended. Inability to correct the core body temperature within 30 minutes necessitates transfer to a medical facility. Initial serum blood testing is unnecessary.

Normal vital signs with abnormal mental status. An athlete who has normal vital signs and pulse oximetry is unlikely to have a life-threatening cardiopulmonary condition. A pulse faster than 80/min may be abnormal for a trained endurance athlete. Ischemia and myocardial infarction are still possible culprits and should be ruled out with an electrocardiogram, and further lab testing may be necessary. Neurologic conditions, including intracerebral bleeding and seizure, are also possible causes of an altered mental status.

Hyponatremia. Endurance athletes, especially those requiring more than 4 to 5 hours to complete a marathon, are at risk for symptomatic hyponatremia.8 A high incidence of hyponatremia in marathon runners is unique in the United States and occurred in up to 13% of runners in the 2003 Boston Marathon.9 As athletes ingest excessive water, serum sodium levels fall, and confusion, nausea, vomiting, ataxia, coma, and, potentially, death can occur. For this reason, any IV fluids should be infused with caution pending the results of the serum sodium test. Initial treatment of symptomatic hyponatremia in the race medical tent begins with free-water restriction and encouragement to urinate, followed by transfer to a medical facility for cautious IV infusion of 3% sodium chloride (NaCl).

Hypoglycemia. Although uncommon, exercise-associated hypoglycemia can lead to an altered mental state. A finger-stick glucometer check is also recommended. Symptomatic hypoglycemia, depending on severity, may be treated with oral glucose-containing solutions or IV dextrose solutions. In any event, the athlete whose mental status does not improve within 15 to 30 minutes should be evacuated for further diagnostic tests and evaluation.10

Unconscious and/or clinically unstable. The most worrisome scenario for race medical providers is the athlete who collapses and loses consciousness. The athlete's airway should be protected, and breathing and circulation should be assessed immediately. Oxygen is administered. Vital signs are obtained as soon as safely and feasibly possible. Legs and pelvis are elevated above the level of the heart while a cardiac monitor is being placed. The ACLS protocols are initiated if the athlete becomes clinically unstable. The unconscious endurance athlete with normal vital signs, including normal core body temperature, should cautiously be treated as having symptomatic hyponatremia.10 IV access is appropriate with blood drawn for testing. Athletes who have suspected or documented hyponatremia should be restricted from drinking water and transported to a hospital for further evaluation, monitoring, and sodium level correction with 3% NaCl.

Heatstroke. All hyperthermic patients who have altered consciousness and core temperatures of 40°C (104°F) or higher need to be cooled aggressively and treated for heatstroke. Athletes can be placed in a child's plastic swimming pool with their arms and legs hanging over the sides. The pool is filled with cool water or water and ice. Antipyretic agents are not advised for heat injuries.11 Benzodiazepines are reserved for athletes with heat injuries who are having seizures and not responding to corrective nonpharmacologic treatment. Hypothermic athletes need to be rapidly but gently warmed. Unstable vital signs, hyper- or hypothermia that persists for more than 30 minutes, prolonged unconsciousness, and/or the development of an arrhythmia require urgent transfer to a medical facility (table 5).

TABLE 5. Medical Conditions Requiring Evacuation to an Emergency Department
Any seizure activity
Arrhythmia or ischemic changes seen on ECG
Cardiopulmonary resuscitation initiated
Dark urine and symptoms suggestive of rhabdomyolysis
Generalized severe muscle cramps unresponsive to conservative treatment measures
Persistent hyper- or hypothermia
Symptomatic hypoglycemia that does not respond to routine medical interventions
Symptomatic hyponatremia
Unstable vital signs or persistently altered mental status despite 15-30 min of pelvic/extremity elevation and/or 1-2 L of attempted fluid resuscitation

Intravenous Fluids: Choices and Indications

One of the most difficult decisions that the treating physician confronts is when to start IV fluids. Noakes and colleagues have devoted considerable attention to this question, and they have studied the role of dehydration in collapse. Several studies1,3 failed to demonstrate significant differences in biochemical markers between athletes who develop EAC and control subjects. Most individuals who collapse at or shortly after the finish line do so as a manifestaton of EAC, are not severely dehydrated, and improve rapidly with leg and pelvis elevation and oral rehydration.

The choice of IV fluids is somewhat controversial. The American College of Sports Medicine in its position stand12 does not recommend a specific choice of fluid, but it acknowledges that 5% dextrose in either 0.45% or 0.9% normal saline are most commonly used. Laird5 prefers to use 5% dextrose in 0.9% normal saline at the Ironman Triathlon World Championship in Hawaii. Roberts2 prefers to use 5% dextrose in 0.45% saline for all severely dehydrated runners and for moderately ill athletes who are unable to tolerate oral fluids.

In our experience as medical consultants for the Marine Corps Marathon, the Army Ten-Miler, the Washington DC Marathon, and the Ironman Triathlon World Championship, we commonly use 5% dextrose in 0.9% normal saline. If the athlete requires more than 2 L of IV fluid without clinical improvement and/or hemodynamic stabilization, we recommend evacuation to a medical facility.

Finishing Thoughts

The collapsed athlete must be triaged and managed appropriately to minimize morbidity and mortality. Family physicians and other volunteer medical providers need a systematic approach to triage that ultimately places athletes into severe or nonsevere categories. Serious medical conditions must be ruled out or stabilized and managed as quickly as possible. EAC is the most common reason for collapse at or near the finish line, and IV fluids are needed only under certain clinical circumstances. Unstable athletes and those not responding to conservative therapy should be urgently evacuated to a medical facility.

The views and statements contained in this article are the authors' and do not reflect those of the United States Army or the United States government.


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Dr Brennan is the director of the Tri-Service Primary Care Sports Medicine Fellowship program at the Uniformed Services University of the Health Sciences in Bethesda, Maryland. Dr O'Connor is chief of family medicine at Dewitt Army Community Hospital, Fort Belvoir, Virginia, and associate director for the Tri-Service Primary Care Sports Medicine Fellowship Program. Both are team physicians for George Mason University in Fairfax, Virginia. Address correspondence to LTC Fred H. Brennan, Jr, DO, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd, Bethesda, MD 20814-4799; e-mail to [email protected].

Disclosure information: Drs Brennan and O'Connor disclose no significant relationship with any manufacturer of any commercial product mentioned in this article. No drug is mentioned in this article for an unlabeled use.