Snow shoveling is a known trigger for heart attacks. Emergency departments in the snow-belt gear up for extra cases when enough of the white stuff has fallen to force folks out of their homes armed with shovels or snow blowers.

What’s the connection? Many people who shovel snow rarely exercise. Picking up a shovel and moving hundreds of pounds of snow, particularly after doing nothing physical for several months, can put a big strain on the heart. Pushing a heavy snow blower can do the same thing. Cold weather is another contributor because it can boost blood pressure, interrupt blood flow to part of the heart, and make blood more likely to form clots.

When a blood clot forms inside a coronary artery (a vessel that nourishes the heart), it can completely block blood flow to part of the heart. Cut off from their supply of life-sustaining oxygen and nutrients, heart muscle cells begin to shut down, and then die. This is what doctors call a myocardial infarction or acute coronary syndrome. The rest of us call it a heart attack.

The so-called classic signs of a heart attack are a squeezing pain in the chest, shortness of breath, pain that radiates up to the left shoulder and down the left arm, or a cold sweat. Other signs that are equally common include jaw pain, lower back pain, unexplained fatigue or nausea, and anxiety.

Here are some tips for safe shoveling:

Warm up your muscles before starting.

Shovel many light loads instead of fewer heavy ones.

Take frequent breaks.

Drink plenty of water.

Don’t feel that you need to clear every speck of snow from your property.

Head indoors right away if your chest starts hurting, you feel lightheaded or short of breath, your heart starts racing, or some other physical change makes you nervous. If you think you are having a heart attack, call 911 or your local emergency number.

If you are out of shape or worried about your heart, hire a teenage neighbor. He or she could use the money, and probably the exercise.