You're warned every year, but it bears repeating as the northeast starts to dig out from as much as 30 inches of snow: Shoveling lots of wet, heavy snow presents a real risk of heart attack if you're not in shape to do it. And musculoskeletal injuries are even more common.

Here are some tips from a story I did last February (with a little editing to remove references to the 2014 snowstorm in Washington). Follow them. They could save your life, or your back.

Every major snowstorm unfortunately sends two categories of people to seek medical care: those who suffer heart attacks and those who sustain orthopedic injuries.

Make no mistake: Shoveling lots of wet, heavy snow can kill you.

“Shoveling snow is a significant physical effort,” said John G. Harold, president of the American College of Cardiology. “Patients who have known coronary disease under management and treatment are obviously a group that would be advised not to shovel snow.”

A second group consists of people with a variety of risk factors but no history of coronary disease. Smokers, anyone with a strong family history of heart disease and those with high blood pressure are some examples, Harold said. If you fit those categories and are middle-aged or older, take particular caution, he said. Across the population, more heart attacks occur in winter than in summer.

If you do get out there, watch for symptoms of heart difficulties: unexpected chest tightness, shortness of breath, and pain or burning in the chest, jaw or shoulder, Harold said. Do not assume that a strange muscular pain is due to exertion. Symptoms of a heart attack include pain referred to other parts of the body.

“It’s all about common sense and logic, and when you sense something is going wrong, don’t force yourself through it,” he said.

Speaking of forcing: In 2012, 34,200 people were treated in hospital emergency rooms for snow removal-related injuries, said Claudette Lajam, an assistant professor of orthopedic surgery at NYU Langone Medical Center’s Hospital for Joint Diseases.

The most common, not surprisingly, are musculoskeletal strains, especially to the lower back, shoulders and knees.

Lajam’s advice: Warm up and stretch a bit indoors before layering up and heading out to shovel. Push the snow instead of lifting it, and don’t twist to throw it. Use a smaller shovel to keep the load down. Practice proper lifting technique: Squat with legs apart and back straight. Pace yourself and take breaks. Don’t get dehydrated.

“A lot of people aren’t in great shape . . . and instead of your muscles taking on the weight of the snow, the burden of the task is taken on by the bones,” she said. Spinal disks also take a beating on days like today, she said.

One more warning, to snowblower users. Under no circumstances should you put a hand or foot in the machine. Clear any obstruction with a tool.

All that considered, shoveling is actually an excellent workout if done properly. According to a 1999 surgeon general’s report, 15 minutes of snow-shoveling qualifies as a “moderate amount of physical activity,” the kind the government wants you to do nearly every day.