Medical Concerns of Marathons : Current Sports Medicine Reports

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Medical Concerns of Marathons

Jaworski, Carrie A. MD

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Current Sports Medicine Reports 4(3):p 137-143, June 2005. | DOI: 10.1097/01.CSMR.0000306196.51994.5f
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One must remember that the first marathon runner, Phidippides, collapsed and died at the finish of his race. Fortunately, death has been an infrequent occurrence in modern day marathons. However, the physical exertion required to complete a marathon coupled with exposure to often harsh environmental conditions and an increase in the number of novice participants makes injuries inevitable. The medical team's main goal is to implement strategies to prevent serious injury and illness through pre-event planning, race day preparedness, and postevent evaluations. The three general categories of injuries encountered with marathon participation include medical conditions, musculoskeletal injuries, and dermatologic complaints. The focus of this article is on the evaluation and management of the varied medical concerns encountered on race day along with the essentials in prerace planning and preparedness.


The past decade has seen an increase in the sport of running as a means to achieve and maintain fitness. It is estimated that there are now more than 30 million adult runners in the United States [1]. For many of these runners, completing a marathon is the ultimate test. The concepts of charity-based running and group training programs have become common methods for recreational runners to achieve this goal. For these reasons, the popularity of marathon participation has been consistently increasing among recreational runners.

What was once thought of as a sport of only the most talented of distance runners, has now become the playing field for eager runners of all ages and abilities. Popular races such as the Twin Cities Marathon in Minnesota, the Marine Corp Marathon in Washington, DC, and the LaSalle Bank Chicago Marathon in Illinois frequently close registration months before race day. These demographic changes have lead to an increase in the average finish time from 3 to 4 hours over the past decade [1]. Along with this increased interest, has been an increase in the number of races, with greater than 300 marathons held annually [1]. Taking all of this into account, the role of the medical team at each of these races has become paramount in keeping participants out of harm's way.

Injury Prevention and Planning

Medical coverage of a marathon requires the cooperation of many individuals within a community. Securing the help of local hospitals, physicians, nurses, emergency medical technicians (EMTs), and other allied health professionals to work as the medical team is essential in the early planning stages. Notifying local police and fire departments to assist the medical team in the care and safety of athletes is also necessary. Some races may also need to solicit area businesses to provide financial support for the medical and nonmedical supplies [2].

The primary goal of the medical team is to ensure the safety of all competitors. A secondary goal is to prevent overload of local emergency rooms on race day through proper treatment and triage of injuries. Additionally, marathons have become a widely popular spectator sport with thousands of people spaced out over a 42-km playing field. Big city marathons have been known to attract close to a million spectators, if not more. Although it is typically not the responsibility of the medical team to care for spectators, in the post-9/11 era, medical directors should be prepared to oversee and execute a disaster plan in the event of mass casualty [2,3•].

The medical director must work in collaboration with the race director to establish policies regarding the above issues in addition to policies on race participation, liability and necessary competitor education. Important to medical volunteers is the fact that “good samaritan” laws may no longer protect event physicians, thus necessitating individual coverage or extension of the event coverage to include the medical staff [4•].

Although it is unreasonable to expect an injury-free event, medical directors should seek to minimize disability and injury by offering the safest course possible. Through the use of historic data on local environmental conditions, the most appropriate time of year to race and safe start times to allow for safe start and finish times for all levels of competitors can be established [3•]. Predetermination of hazardous conditions that would necessitate cancellation or postponement of the race should be published in advance as should an impaired competitor policy to outline criteria for medical disqualification.

Use of the wet bulb globe temperature index as a measure of thermal injury risk on race day is recommended by the American College of Sports Medicine during all endurance running events. It accounts for humidity, wind speed, and radiant heat. Race day measurements can be displayed at the start via a colored flag system with explanations/definitions provided to competitors prior to race day (Table 1) [5].

Table 1:
Flag system for risk of thermal injury

Knowledge of expected injuries and illnesses can aid in determining supply and staffing needs. The incidence and types of casualties likely to be encountered is best predicted by data from the specific event's previous years. Unfortunately, these data may be unavailable or inaccurate for many races. In those instances, one can use the predicted incidence of injury to calculate needs until event-specific data are available. This is calculated using anticipated number of participants multiplied by casualty incidence. The casualty incidence for running 42-km can range anywhere from 1% to 20% in the literature and varies mainly based on environmental factors [2,6].

General guidelines in terms of staffing and medical aid stations have been established to assist race directors. Ratios of 1 to 2 physicians per 1000 runners, along with two to four nurses (one with intravenous [IV] experience), one to four EMTs, four to six podiatrists, three to six physical therapists, athletic trainers, or massage therapists, and one to three assistants have been quoted previously [5]. Personnel should have easily identifiable hats or apparel.

The main medical tent should be located near the finish line with the majority of personnel (∼ 75%) stationed in this area. In Chicago, the main tent is a few hundred yards from the finish with an additional medical tent in the nearby vendor pavilion to allow for better access to athletes who may experience difficulty some time after they leave the finish chute. A designated physician triages at the finish line with numerous assistants to aid with transport of the athletes to the main medical tent. Medical tents should consist of a triage area, an intensive medical area, and a general medical area. Further subdivisions into orthopedic and medical conditions can be considered if space allows (Tables 2 and 3). Access should be restricted to participants only, but nonmedical personnel should be available at the entrance to assist concerned friends and family with updates as appropriate.

Table 3:
Secondary aid station supplies
Table 2:
Main medical tent supplies

Aid stations should be positioned approximately every 2 to 3 km along the course. Early aid stations rarely see many competitors, whereas stations beyond the halfway mark tend to deal with more casualties. This should be taken into account when assigning staff. Also, those who prefer to work the main medical tent should avoid being at one of the later aid stations as they will invariably miss the action in the main tent by the time all the participants pass their station on the course.

Fluid stations and previous recommendations on hydration have come under much scrutiny as of late due to issues of overhydration in novice runners and the risk of hyponatremia. Several excellent guidelines have recently been published that explore these issues [7••,8•]. The bottom line is that runners need to determine their individual fluid needs and adhere to that on race day. It is recommended that 6 to 12 oz of fluid be available for every 15 to 20 minutes of continuous activity [3•]. Slower runners need not drink at every station, they should opt for carbohydrate and salt solutions or sports drinks over water, and drink according to thirst consuming no more than 400 to 800 mL/h [7••]. It is also recommended that there be one ambulance per 3000 runners at the finish for hospital transports and additional mobile medical van support for runners who require assistance along the course. Transportation is also necessary for well runners who may drop out along the course [5].

Communication between the medical director and all aid stations, ambulances and local hospitals is essential either via two way radios or dedicated cell phones. A list of these numbers should be provided to the medical team member in charge of each aid station as well as to those involved in the transportation and pick up of injured athletes.

Participant education is yet another aspect of pre-event planning required for a safe and successful marathon. Through web sites and pre-event expositions, participants can be provided with information on training topics, including proper hydration and signs and symptoms of heat or cold illness. They can also obtain race policies and procedures, locations of aid stations and fluid stations, and types of fluid replacement and food types to be used at aid stations so they can train with them prior to race day. Race day education can provide weather updates and warnings through announcements at the start and along the course.

Common Injuries and Medical Problems

Historically, it has been quoted that 2% to 12% of entrants will utilize a medical aid station depending on the difficulty of the course and weather conditions. More recently, a study from the Twin Cities Marathon demonstrated a 1.89% tent visitation rate for entrants and a 2.5% rate for finishers based on 12 years of data. Of note, only 0.1% of those finishers required higher-level care at an emergency room or hospital. Approximately 90% of athletes cared for had mild, self-limiting illnesses. The most frequently seen conditions were exercise-associated collapse (EAC; 59%), skin conditions (21%), and musculoskeletal conditions (17%) [9••].

Approach to the Collapsed Athlete

Exercise-associated collapse is the most frequently seen condition at the finish line of all types of endurance events [9••,10,11,12•]. EAC was initially thought to be secondary to dehydration-induced hyperthermia. Since then, many other medical causes of collapse have been lumped under the heading of EAC, including muscle cramping, hyperthermia, hypothermia, hyponatremia, and hypoglycemia. The current thinking is that true EAC is “the inability to stand or walk unaided as the result of light-headedness, faintness, dizziness, or syncope” as defined by Holtzhausen et al. [13]. Additional defining factors include collapse upon completion of the race and a postural drop in systolic blood pressure of greater than 20 mm Hg from standing to lying [14]. EAC should not be the presumed diagnosis in collapse that occurs prior to the finish as this is a much more ominous sign not typically related to postural hypotension [13].

The cause of postural hypotension in EAC is related to the inactivation of the calf muscle pump upon cessation of prolonged exercise, which results in lower extremity blood pooling, reduced atrial filling pressure, and subsequent syncope. According to Speedy et al. [12•] the majority of runners who collapse at the finish will not have other medical conditions responsible for their collapse, although it is vital to differentiate the other causes of collapse in an efficient and thorough manner.

A good approach to the collapsed patient is to evaluate him in the supine position with his head down and feet and pelvis elevated. For the majority who will have isolated EAC, this should rectify their postural hypotension; they will be mentally alert, and treatment can then be initiated with oral rehydration as indicated. If the athlete, once in the above position, has an altered mental status, or is unconscious, other conditions such as hyponatremia, hyperthermia, hypothermia or hypoglycemia need to be ruled out.

In the athlete with altered mental status, a rectal temperature should be the next step to evaluate for thermal injuries. Rectal temperatures are the only acceptable method of measurement as they reflect the body's core temperature most accurately. An important caveat I learned while recently covering the Ironman Triathlon World Championship in Kona, HI is that any athlete with altered mental status after exercising in the heat should be presumed to have heat stroke and be immediately immersed in an ice bath, even before obtaining a rectal temperature or sodium level. The thought is that no harm will come from cooling someone with hyponatremia temporarily, whereas significant harm can arise from the delayed cooling of a heat stroke victim. Other cooling methods such as ice bags, cooled IV fluids, and fans are considered ineffective during those critical first few minutes.

A rectal temperature greater than 41°C in an unconscious or confused athlete indicates exercise-induced heatstroke. As stated above, it is a life-threatening emergency that requires immediate treatment by ice water immersion. Transfer to a hospital should not be initiated until after the temperature is decreased to avoid catastrophic outcomes. By decreasing the temperature to below 40.8°C within 1 hour, one protects the athlete from the risk of end-organ damage. Ice water immersion can be accomplished with a plastic children's pool or a similar large plastic container such as ones made by Rubbermaid (Atlanta, GA; search “stock tank” at Decreases in temperature need to be monitored as to prevent overcooling. The standard recommendation is to remove the athlete from the immersion once the temperature reaches approximately 38°C. IV fluids can be given simultaneously if there is coexisting dehydration [15•].

The other end of the spectrum is hypothermia, defined as a temperature under 36°C and also associated with mental status changes in severe cases. Mild hypothermia (34°–36°C) can usually be corrected with removal of wet clothes, warm blankets, and warm fluids. Moderate (30°–34°C) and severe cases (< 30°C) are more concerning as there is the risk of ventricular fibrillation with physical manipulation in severe cases. These patients should be wrapped gently in a warm blanket and transferred to the emergency room for passive reheating [2,5]. It is important to keep in mind that both hypothermia and hyperthermia can present to the medical tent on the same day depending on weather conditions and participant's length of exposure to the elements.

A normothermic athlete with mental status changes should be presumed to have hyponatremia until proven otherwise [12•]. Hyponatremia, defined as a serum sodium under 135 mg/dL, actually has a low reported incidence in marathons, although it is seen in 10% to 40% of ultradistance athletes [16–19]. It is thought to be due to the replacement of hypertonic sweat with a hypotonic fluid. The symptoms depend on the severity of the sodium deficit. Mild hyponatremia (> 130 mg/dL) is frequently asymptomatic, whereas severe hyponatremia (< 125 mg Hg) can present with altered mental status, confusion, or seizures.

The risk of hyponatremia during a marathon is greatest in the back of the pack runner where a slow pace equals more time to drink at aid stations and less sweat loss [18,19]. These patients become overhydrated and frequently will demonstrate weight gain during the race as well as tightening of their rings, watches, and/or race bands.

Prevention through participant education is the best treatment for this phenomenon. If that fails, treatment in mild cases is mainly one of observation, whereas severe alterations in mental status, pulmonary edema, or seizures warrants transfer to the emergency room. IV and oral fluids should be avoided in the overhydrated hyponatemic patient as fluid overload is their problem. Normal saline can be considered in the athlete who also appears significantly dehydrated and cannot tolerate oral rehydration. Administration of hypertonic saline (3%–5%) to treat severe hyponatremia is typically left to the hospital setting where close monitoring is available, but could be considered at a slow rate of less than 50 mL/h in severe cases where transport is prolonged or delayed [12•]. The policy at the Chicago Marathon, as with many other races, is that no IV fluids can be given without first obtaining an electrolyte panel on the patient and IV fluids can not be administered if the serum sodium is less than 130 mg/dL.

Dehydration can accompany any of the above conditions and is clinically diagnosed by dry mucous membranes, decreased skin turgor, decreased urine output, inability to spit, orthostatic hypotension, and tachycardia and weight loss. If a patient fails to respond to elevation of the legs and pelvis, and remains hypotensive, dehydration should be considered and rehydration measures should be instituted. Mild cases can usually correct with oral fluids, whereas more symptomatic patients may benefit from IV fluids to assist with recovery. Contraindications to IV fluids would be a serum sodium under 130 mg/dL. Hypoglycemia is a rare cause of collapse in marathon participants. It can be seen in a type I diabetic who did not ingest enough carbohydrate during exercise or in someone with an eating disorder. Treatment for severe cases should be with dextrose 50% in water (D50W) 50 mL by IV push [4•].

Other Medical Conditions

Exercise-related muscle cramps

Muscle cramps can occur during or after prolonged exercise, especially in hot, humid conditions. Studies have found a 30% to 50% prevalence of cramping in marathon participants [20]. Numerous theories exist as to the etiology of exercise-related muscle cramps with muscle fatigue and a resultant alteration in alpha motor neuron control at the spinal level as a leading hypothesis [20]. Treatment is aimed at maintaining the cramped muscle in an elongated position with passive stretching. Assisted walking should be encouraged as tolerated. One can also consider diazepam (5 mg IV push) or IV magnesium sulfate (2–4g) for severe or refractory muscle cramping.

Cardiac events

The relative risk of sudden cardiac death with marathon participation is often quoted as 1 in 50,000 [21]. This is a fivefold increase from that of the general population without known cardiac disease. Siegel [22] demonstrated a rise in inflammatory and prothrombotic markers with a persistence of select procoagulant effects in middle-aged male marathon runners the day after the race, which may explain this phenomenon.

Although any suspected cardiac patient should be an automatic transfer to the hospital, some may actually require in the field assistance. Cardioversion should be attempted as soon as possible in appropriate cases. It has also been suggested to modify the advanced cardiac life support protocol by considering use of 50% dextrose in water for substrate repletion, high-dose IV epinephrine (5–10 mg), as exercise depletes catecholamines, and sodium bicarbonate, to reverse metabolic acidosis of activity [4•]. These types of modifications should be done under the supervision of a cardiologist or critical care physician.

Pulmonary issues

Many long-distance runners have underlying asthma or exercise-induced bronchospasm and may experience an exacerbation on race day. Standard treatment protocols should be established and common medications such as albuterol and oxygen should be available to assist with treatment. Similar to cardiac issues, respiratory arrests in a marathon setting warrant automatic transfer to the hospital as do asthma exacerbations unresponsive to initial treatment.

Gastrointestinal issues

Gastrointestinal (GI) complaints, although common in runners, are fairly uncommon in the marathon medical tent. The most common concern related to distance running and the GI tract is that of bleeding. Multiple theories exist as to the cause of bleeding, including nonsteroidal anti-inflammatory drug use, shearing forces, bowel ischemia, and underlying pathology. Studies have demonstrated that 8% to 22% of marathon runners report gross fecal blood loss [23,24]. This is usually discovered by the athlete hours after the race has ended and is therefore not a commonly encountered complaint in the medical tent. Generally, however, exercise associated GI bleeding is occult and only detected by Hemoccult (Beckman Coulter, Fullerton, CA) fecal blood testing or when an athlete later presents with symptoms of anemia. One must always be vigilant in ruling out other causes of GI bleeding before assigning exercise as the culprit.

Smetanka et al. [25] found that a majority of participants in the 1996 Chicago Marathon used ibuprofen or aspirin before or during the race. The study also demonstrated that the use of ibuprofen by these subjects lead to an increase in intestinal permeability resulting in a breakdown in the GI tract barrier. Other studies have found increased permeability with aspirin usage [26,27].

Other commonly reported GI complaints seen on or following race day include nausea and vomiting, heartburn, diarrhea, and bloating [28]. Adjustments in dietary intake with limitations of lactose and fiber intake as well as adjustments to timing of meals may have a positive impact [28]. Management in the medical tent is based on controlling symptoms and encouraging future workups as appropriate.

Musculoskeletal Conditions

The two main types of musculoskeletal issues seen in a marathon setting are overuse injuries and trauma. Overuse injuries may be acute in presentation or a flare of a more chronic problem. Muscle strains, including tendonitis and low back pain, represented the greatest number of musculoskeletal complaints with 14.3% of injuries in the Twin Cities Marathon study [9••]. Other commonly seen injuries include medial tibial stress syndrome, plantar fasciitis, iliotibial band syndrome, and lower extremity stress fractures. Trauma can include completed fractures, injuries and contusions secondary to falls and collisions, and dislocations.

The common approach to treatment of the majority of these conditions is the standard RICE protocol (rest, ice, compression, and elevation). Obvious fractures need transport to the hospital for definitive care as does any condition that is not responding to routine treatment. If an minor injury occurs on the course, a competitor can be allowed to continue provided they can maintain their competitive posture and progress in a straight line towards the finish [4•]. Follow-up at subsequent aid stations should be encouraged.

Skin Conditions

Perhaps the most annoying of all injuries, friction blisters can wreak havoc on a runner's marathon experience. Blisters may be considered the most common of sports injuries with the Twin Cities Marathon study citing a 19.9% incidence [9••]. The best treatment is undoubtedly prevention. Properly fitted footwear, avoidance of cotton and wool socks because they retain moisture, and use of aluminum-based antiperspirants on the feet to decrease moisture and friction have all proven beneficial [29].

Treatment of blisters during the race should be limited to protection in the form of hydrocolloidal patches or donut pads. Application of petroleum jelly may be detrimental during the race, as studies have demonstrated an increase in friction after 1 hour of exercise [30]. Avoid the temptation to unroof the blister, unless it has three edges free, at which point careful cutting away of the loose flap is advised. Drainage should be limited to those blisters larger than 5 mm in size and preferably done after 24 hours [29]. We usually recommend that the athlete return home and shower prior to drainage of the blister as sterile techniques and clean dressings done in the medical tent are ruined once the athlete attempts to shower. Instructions on dressing changes and signs of infection should be provided to the athlete before discharge from the medical tent.

Postrace Evaluation

At the conclusion of a race, medical records should be collected and later evaluated for trends in injuries and illness. Any adverse events should be reviewed to determine if the event could have been prevented and to possibly prevent future occurrences. Planning for the following year begins almost immediately for many of the larger races.


Medical coverage of a marathon is an arduous task that requires careful planning and the participation of many people. The growth of the sport among recreational runners has increased the need for an experienced medical staff. Using previous experience and education of participants before race day can help to alleviate many potential problems. As for the future, collaboration between marathon medical directors at meetings such as the American Road Race Medical Society and the International Marathon Medical Directors Association will hopefully provide more research data about the sport. A recent suggestion has been to develop a participant death and injury registry. This will allow for better tracking and sharing of data between the many races. Steps such as this will undoubtedly allow for continued improvements in the care of all marathon runners.

References and Recommended Reading

Papers of particular interest, published recently, have been highlighted as: • Of importance, •• Of major importance

1. USA Track and Field State of the Sport Report and statistics.
2. Jaworski CA: Marathon.Sports Injuries & Emergencies: A Quick Response Manual. Edited by Rubin AL. New York: McGraw-Hill; 2003:314–324.
3.• American College of Sports Medicine. Mass participation event management for the team physician: a consensus statement.Med Sci Sports Exerc 2004, 36:2004–2008.

Recently released consensus statement on coverage of mass participation events. Concise and good reference list.

4.• Roberts WO: Administration and medical management of mass participation endurance events.Team Physician's Handbook. Edited by Mellion MB, Walsh WM, Madden C, et al. Philadelphia: Hanley & Belfus; 2002:748–756.

Dr. Roberts is one of the leaders in the field of marathon coverage. This is a thorough review of how to successfully provide medical coverage of a mass participation endurance event.

5. American College of Sports Medicine. Position statement on heat and cold illnesses during distance running.Med Sci Sports Exerc 1996, 28:i–vii.
6. Jones BH, Roberts WO: Medical management of endurance events.ACSM Guidelines for the Team Physician. Edited by Cantu RC, Micheli LJ. Philadelphia: Lea & Febiger; 1991:266–286.
7.•• Noakes T: Fluid replacement during marathon running.Clin J Sport Med 2003, 13:309–318.

A thought provoking article that makes recommendations based on clinical evidence with regard to hydration issues in all levels of marathon runners.

8.• Casa DJ: Proper hydration for distance running-identifying individual fluid needs. A USA Track & Field Advisory.

A good reference to provide to interested athletes, it describes how to monitor one's own fluid needs.

9.•• Roberts WO: A 12-year profile of medical injury and illness for the Twin Cities Marathon.Med Sci Sports Exerc 2000, 32:1549–1555.

Provides much-needed data on what medical teams are seeing on race day with correlations between weather and injury rates.

10. Crouse B, Beattie K: Marathon medical services: strategies to reduce runner morbidity.Med Sci Sports Exerc 1996, 28:1093–1096.
11. Martinez JM, Laird R: Managing triathlon competition.Curr Sports Med Rep 2003, 2:142–146.
12.• Speedy DB, Noakes TD, Holtzhausen LM: Exercise associated collapse. Postural hypotension, or something deadlier?Phys Sportsmed 2003, 31: 23–29.

An excellent review of exercise-associated collapse which provides an organized method for diagnosing and treating the collapsed athlete.

13. Holtzhausen LM, Noakes TD, Kroning B, et al.: Clinical and biochemical characteristics of collapsed ultra-marathon runners.Med Sci Sports Exerc 1994, 26:1095–1101.
14. Holtzhausen LM, Noakes TD: The prevalence and significance of post-exercise (postural) hypotension in ultramarathon runners.Med Sci Sports Exerc 1995, 27:1595–1601.
15.• Casa DJ, Almquist J, Anderson S, et al.: Inter-association task force on exertional heat illnesses consensus statement.NATA NEWS 2003,24–29.

Another important article to provide to coaches, athletes, and parents on a potentially life-threatening condition. A quick review to keep on hand.

16. Speedy DB, Noakes TD, Rogers IR, et al.: Hyponatremia in ultradistance triathletes.Med Sci Sports Exerc 1999, 31:809–815.
17. Hiller WD, O'Toole ML, Fortess EE, et al.: Medical and physiological considerations in triathlons.Am J Sports Med 1987, 15:164–167.
18. Hew TD, Chorley JN, Cianca JC, et al.: The incidence, risk factors, and clinical manifestations of hyponatremia in marathon runners.Clin J Sport Med 2003, 13:41–47.
19. Hsieh M, Roth R, Davis DL, et al.: Hyponatremia in runners requiring on-site medical treatment at a single marathon.Med Sci Sports Exerc 2002, 34:185–189.
20. Schwellnus MP, Derman EW, Noakes TD: Aetiology of skeletal muscle ‘cramps’ during exercise: a novel hypothesis.J Sports Sci 1997, 15:277–285.
21. Maron BJ, Poliac LC, Roberts WO: Risk of sudden cardiac death associated with marathon running.J Am Coll Cardiol 1996, 28:428–431.
22. Siegel AJ: Effect of marathon running on inflammatory and hemostatic markers.
23. Baska RS, Moses FM, Graeber G, et al.: Gastrointestinal bleeding during an ultramarathon.Dig Dis Sci 1990, 35:276–279.
24. Green GA: Gastrointestinal disorders in the athlete.Clin Sports Med 1992, 11:453–470.
25. Smetanka RD, Lambert GP, Murray R, et al.: Intestinal permeability in runners in the 1996 Chicago marathon.Int J Sport Nutr 1999, 9:426–433.
26. Ryan AJ, Chang RT, Gisolfi CV: Gastrointestinal permeability following aspirin intake and prolonged running.Med Sci Sports Exerc 1996, 28:698–705.
27. Lambert GP, Broussard LJ, Mason BL, et al.: Gastrointestinal permeability during exercise: effects of aspirin and energy-containing beverages.J Appl Physiol 2001, 90:2075–2080.
28. Simons SM, Kennedy RG: Gastrointestinal problems in runners.Curr Sports Med Rep 2004, 3:112–116.
29. Brennan FH: Managing blisters in competitive athletes.Curr Sports Med Rep 2002, 1:319–322.
30. Knapik JJ: Risk factors for foot blisters during road marching: tobacco use, ethnicity, foot type, previous illness and others.Mil Med 1999, 164:92–97.
© 2005 American College of Sports Medicine