Is the threat of a heart attack while shoveling snow an urban legend? Actually, it's very real and deadly. A 1996 New England Journal of Medicine study pointed out that these sudden heart attacks can strike people with no history of heart disease, and are more likely to occur in older people with otherwise sedentary lifestyles.

This particular chore is so deadly because of a combination of factors. First, the activity is strenuous—it can burn up to 200 calories in 30 minutes. Second, it is done in the cold which causes blood vessels and arteries to constrict and make a heart attack more likely.

The best ways to protect yourself are:

• Shovel early when the snow is lighter.
• Use proper technique—try pushing the snow instead of lifting it. If you have to lift, use your legs, not your back.
• Stay hydrated, as you would with any intense exercise.
• Take breaks often.
• Know the warning signs of a heart attack: chest pain, arm pain, dizziness, fainting, nausea or shortness of breath.

If you have a history of heart problems, consult your doctor before any physical exertion including snow shoveling.