The snow has already begun to fall, for many people the task of shoveling snow is staring them in the face. Research determines that that shoveling snow sends more than 11,000 people to the hospital every year while the majority of the 1,200+ deaths that occur each year during or immediately following a major snowstorm are due to shoveling snow. This increased death rate is attributed to decrease in ambient temperatures and snow shoveling. The majority of these deaths occur in people that do not exercise regularly, or have been previously diagnosed with heart disease.
The physiological changes that occur during snow shoveling such as increased blood pressure and heart rate, are comparable to, or exceed those experienced during a “stress test”. A stress test is a diagnostic test used by physicians to detect heart disease. Stress test is conducted in a hospital setting, with medical doctors in close proximity with appropriate equipment to deal with any emergency. That is not the case in your driveway.
A number of characteristics of snow shoveling contribute to excessive cardiovascular demands. These include working in an upright position using the arms, breath holding and straining while lifting the snow and the inhalation of cold air. Inhalation of cold air induces a reflex spasm or constriction of the coronary arteries. In the presence of coronary artery disease, whether diagnosed or not, these factors may lead to acute myocardial infarction (sudden heart attack), life threatening irregular heartbeats, and cardiac arrest (sudden death).
Snow shoveling is usually performed in the morning; this is also the time when most heart attacks and heart rhythm disturbances occur. The cold weather is also associated with an increase in angina or “chest pain” with physical exertion in people with angina. A possible reason for this is the fact that the skin’s blood vessels constrict in order to conserve body heat. This causes the heart to work harder to force blood through the smaller blood vessels. Since most people generally hold their breath during activity, the amount of available oxygen to the heart is decreased, causing angina. Although there is greater cardiovascular demand during snow shoveling, it actually requires less oxygen for working muscles than other forms of activity. This means that the usual signs and symptoms of overexertion dizziness, fatigue, nausea, and breathlessness) that typically cause a person to stop activity are not present. The person usually continues to shovel.
It is a combination of vigorous physical exertion and a disease or susceptible heart that puts the cardiovascular system and person in jeopardy. Problems occur with the assumption that all symptom-free individuals are free from disease and that is not always the case. With approximately 16% of all heart attacks, the first, last, and only symptom suggestive of heart disease (dizziness, chest pain, heart rhythms abnormalities) or with one or more of the coronary artery disease risk factors should use extreme caution. Healthy individuals who exercise regularly should not be overly concerned but should still pace themselves.
Regular anaerobic/aerobic exercise three times per week and common sense will be your biggest assets toward prevention.