People with heart disease may not be able to compensate for their bodies’ higher demand for oxygen when inhaling cold air. This means that snow shoveling and other activities are dangerous for some people. And that is a piece of health advice not worth ignoring.
Breathing cold air during exercise can cause uneven oxygen distribution throughout the heart. But a healthy body generally corrects for this problem and redistributes blood flow, making sure the heart continues to function properly. In people with heart problems — such as coronary artery disease — this may not be the case.
So, if you are doing some type of “isometric work” and you’re breathing cold air, your heart is doing more work. It is consuming more oxygen. Isometric work includes such activities as shoveling snow and carrying a briefcase or laptop bag. The heart works harder when exerted in cold temperatures and the number of deaths due to cardiac arrest peaks during the winter.
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The researchers thought that oxygen demand in the heart would be higher with cold-air breathing and also thought that oxygen supply would be a little bit impaired. And that’s generally what they found. Their study was published in two different medical journals this month.
The researchers first studied healthy young adults before looking at a group of healthy older adults in their 60s so that they could learn how the heart functions in people without disease. Each subject was monitored for lung function and heart function during the trials.
In order to measure heart function during exercise, the participants performed an isometric, or static, handgrip, which is a maneuver known to increase blood pressure. Subjects squeezed the handgrip device and held it still for two minutes. Researchers found a supply-demand mismatch in the left ventricle — where the heart receives oxygenated blood — yet the heart was able to continue functioning appropriately.
Thus, healthy people can redistribute blood to vessels entering the heart in cold air exercise. But those with heart disease face a greater challenge. If you suffer any issues with your ticker, be careful when exerting yourself outside.