Cardiac Risks Associated With Marathon Running

Competitive sports are associated with an increase in the risk of sudden cardiovascular death (SCD) in susceptible adolescents and young adults with underlying cardiovascular disorders. In middle-age/older individuals, physical activity can be regarded as a ‘two-edged sword’: vigorous exertion increases the incidence of acute coronary events in those who did not exercise regularly, whereas habitual physical activity reduces the overall risk of myocardial infarction and SCD.

Marathon running is associated with a transient and very low risk of SCD. This risk appears to be even lower in women and is independent of marathon experience or the presence of previously reported symptoms. Most deaths are due to underlying coronary artery disease.

The primary purpose of pre-participation screening is to identify athletes affected by unsuspected cardiovascular diseases and to prevent SCD during sports by appropriate interventions.  The American College of Cardiology (ACC) states that the ultimate goal of athletic screening is the detection of silent cardiovascular abnormalities that can lead to SCD. The overall prevalence of cardiovascular diseases that predispose to SCD in young athletes has been estimated to range from 0.2 to 0.7%.

Cardiac diseases detectable by EKG include:

  1. Hypertrophic cardiomyopathy
  2. Arrhythmogenic right ventricular cardiomyopathy/
  3. Dilated cardiomyopathy
  4. Myocarditis
  5. Long QT syndrome
  6. Brugada syndrome
  7. Lenegre disease
  8. Short QT syndrome
  9. Preexcitation syndrome (WPW)
  10. Coronary artery diseases

Evaluation of young athletes:



Screening of athletes with abnormal EKGs:


Sudden cardiac death can be treated and reversed, but emergency action must take place almost immediately. Survival can be as high as 90 percent if treatment is initiated within the first minutes after SCD. The rate decreases by about 10 percent each minute longer. Those who survive have a good long-term outlook.

If someone experiences sudden cardiac arrest:

  • Call 9-1-1 or 9-9-9/1-1-2 depending on the country (US, UK) should be dialed immediately
  • Begin to perform CPR . If performed properly, CPR can help save a life, as the procedure keeps blood and oxygen circulating through the body until emergency medical help arrives.
  • Early defibrillation. If a public access defibrillator -- also called an AED (Ambulatory External Defibrillator) -- is available, defibrillate. In adults, sudden cardiac death is usually related to ventricular fibrillation. Quick defibrillation (delivery of an electrical shock) is necessary to return the heart rhythm to a normal heartbeat. The shorter the time until defibrillation, the greater the chance the patient will survive. It is CPR plus defibrillation that rescues the person.
  • Once emergency personnel arrive, more traditional defibrillation and initiation of medications can be provided. This type of defibrillation is done through an electric shock given to the heart through paddles placed on the chest.
  • Advanced Care . After successful defibrillation, most patients require hospital care to treat and prevent future cardiac problems.

More about AEDs

Automatic external defibrillators (AEDs) are defibrillators with computers that are able to recognize ventricular fibrillation (VF), advise the operator that a shock is needed, and deliver the shock. AEDs are designed to be used by a wide range of personnel such as fire department personnel, police officers, lifeguards, flight attendants, security guards, teachers, and even family members of high-risk persons. The goal is to provide access defibrillation when needed as quickly as possible. CPR along with AEDs can dramatically increase survival rates for sudden cardiac death.

To learn CPR
Learning CPR is the largest gift you can give your family and friends. CPR is easy for most adults and teens to learn. It is a technique designed to temporarily circulate oxygenated blood through the body of a person whose heart has stopped. It involves:

  1. Assessing the airway
  2. Breathing for the person
  3. Determining if the person is pulseless and applying pressure to the chest to circulate blood

The A-B-Cs of CPR:

A - airway

B - breathing

C - circulation
(chest compressions)

To learn more about CPR: call the national American Heart Association at 1-800-AHA-USA1, or go to the American Heart Association Web site at

(From: Risk of sports: do we need a pre-participation screening for competitive and leisure athletes? Domenico Corrado et al, Eur Heart J. 2011 Jan 29)