Exercise has been associated with good health and fitness, as a result, death during or immediately after exercise tends to have a larger emotional and social impact. The death of a young athlete who is presumed to be healthy can potentially create an exaggerated emotional reaction. Find out more about how and why this could occur and what are the best measures to prevent it.

Contents

Sudden death during exercise: Causes and Prevention.. 1

What is sudden death?. 1

How common are cases of sudden death?. 1

What are the reasons for sudden death?. 2

Exercise Paradox - Does the quantity or frequency of exercise matter?. 2

What can be done for the reduction of adverse events?. 3

What is sudden death?
Natural and unexpected death occurring within one hour of the first symptom is referred to as sudden death.

How common are cases of sudden death?
Statistics are variable depending on the population studied and the type of exercise. Western literature reports the incidence to be between 4.6-22 deaths per million people per year in the general population while exercising. In contrast, the general population experiences an incidence of about 500 cases per million per year, regardless of their activity level.

In a study where over 300 subjects who suffered a sudden cardiac arrest (SCA) were analyzed for their level of physical activity just prior to the occurrence of cardiac arrest, the researchers concluded that the vast majority (80%) of the adult subjects were performing light physical activity or were asleep at the time of the event. Men are considered to be at higher risk than women. In men, the risk was reported to be 1 sudden cardiac death per 1.51 million episodes of vigorous exertion. Among athletes, the incidence is estimated to range from 1 in 40,000 to 1 in 80,000 athletes per year.

What are the reasons for sudden death?
Heart-related conditions are the most common reason for sudden death in general and also during exercise.  >75% of deaths in athletes are assigned to heart-related conditions. Classically in those >35 years of age, the cause tends to be due to acquired coronary artery disease (atherosclerosis or blood vessel blockage and its consequences) and in those <35 years it is due to some form of congenital heart problem.

Congenital problems could be structural problems like;

• a thick heart muscle wall,
• abnormal position of heart blood vessels, or
• abnormal conduction of heartbeats, etc.

Sometimes, a hard hit on the chest like a blunt chest injury (commotio cordis) can also cause misfiring within the heart and sudden death. Drug abuse, heat stroke, lung problems, and drowning are some of the other common causes of sudden death in exercising populations. With increasing intensity of sports and longer duration of endurance events, causes like heatstroke are becoming common.

 Exercise Paradox - Does the quantity or frequency of exercise matter?

There is a transient elevation of SCA during moderate to vigorous exercise. However, research in large populations has shown that this gets modified with habitual exercise. A recent meta-analysis of published studies that investigated the association between physical activity and the risk of sudden cardiac death in adults from the general population (not athletes or patients) found that participants reporting the highest level of physical activity had approximately half the risk of sudden cardiac death compared to those with the lowest level of activity. The relative risk of SCA was significantly lower among men with the highest level of habitual vigorous activity. In contrast, if people are sedentary, their risk was 56-fold higher during exercise.

Among 69,693 women without a medical history, the amount of moderate to vigorous exercise was inversely related to sudden cardiac death risk. The reduction in sudden cardiac death risk was observed primarily among women who exercised four or more hours per week.

In a study of patients with existing coronary artery disease, inactive coronary artery disease patients had a 2.4-fold increased risk for sudden cardiac death compared with active patients. Those who were symptomatic among them had a higher risk if they were highly active (7.4x) or inactive (3.6x) as compared with moderately active patients. This signifies that those with and without known disease and symptoms need a different exercise prescription.

What can be done for the reduction of adverse events?
There is a theory of substrate and trigger for any adverse event. In this case, the trigger is exercise and for it to cause an event, the substrate of the heart condition would often be pre-existing. Thus, a reduction can be achieved by an appropriate pre-exercise medical evaluation (PPME-preparticipation medical evaluation) on a regular basis. Depending on the type of exercise, age and medical background of the person, this evaluation is carried out by professionals trained in this field.

In addition to this, everyone from the exercisers to parents, coaches, support staff and bystanders should be made aware of the signs and symptoms like chest pain, fainting, etc to look out for during exercise. Finally, Basic Life support (BLS) when administered on time and correctly is of great value if an event does occur. It is recommended that everyone undergoes this training regularly and practices it often to be able to act promptly in an emergency.