Can exercise trigger a heart attack?

by Carolyn Thomas  ♥ @HeartSisters

Last winter, I heard about four men in Ottawa – ages 45-72 – who had heart attacks, all on the same afternoon and all while shovelling snow.  Despite news reports like this, it is not true that Ottawa men will do just about anything to get out of doing their chores.

Nor is it true that exercise all by itself will trigger a heart attack.

According to Mayo Clinic cardiologist Dr. Sharonne Hayes:

“All heart attack patients have had an underlying condition that caused the attack.”  

Most heart attacks, in fact, are 20-30 years in the making.

About half of all heart attack survivors, however, mistakenly blame the attack on one specific event – such as extreme exertion.  

Heart attacks generally occur when fatty vulnerable plaque lining an artery wall ruptures and blocks the flow of blood to the heart muscle. A specific physical or emotional stress might contribute indirectly to that rupture, but a heart attack in somebody already seriously at-risk is probably inevitable.

And what about all the men in Ottawa who now believe they have been emancipated from snow-shovelling duties for life after last winter’s headlines?

Clearing snow is sometimes blamed as the culprit because it combines sustained exertion with extremely low temperatures – coincidentally, two of my least favourite things.

Your heart rate and blood pressure increase during strenuous activity. That, coupled with the body’s natural reflex to constrict blood vessels when exposed to the cold, could spell trouble for those already at high risk for heart disease unless they take careful precautions (dressing warmly and taking frequent rest breaks).

The odds that you’ll have a heart attack after any particular round of exercise are still low, despite what men who hate shovelling snow now insist.  

In fact, the more often you exercise, the higher your fitness level and the less likely it is that sudden heavy exertion will set off a cardiac event – unless you already have existing or unaddressed serious risk factors.

And if you don’t exercise regularly, you are likely not strong enough to shovel wet, heavy snow.

I know what you’re thinking:  “But Carolyn, what about Jim Fixx?”

James Fixx, the famous American journalist-turned-fitness guru, was credited with launching the first big running boom with the publication of his landmark book The Complete Guide to Running back in 1977. When Jim Fixx was 52 years old, he dropped dead while out on a seven-kilometre run. Couch potatoes around the world sat up and said in gleeful unison: “See? That’s what happens when you exercise!” as they reached for more Tim Hortons maple dips.

But Jim Fixx was an overweight smoker before he took up running. His blood cholesterol levels were elevated. He had experienced several cardiac warning symptoms which he chose to ignore, and had refused to undergo further testing.  He also had a strong family history of heart disease.  His own father had died of cardiac arrest at the age of 43.

An autopsy showed Fixx had severe coronary artery disease with major blockages in three arteries. In reality, his very high level of fitness had likely helped to give him an extra decade of life compared to every male relative.

In his book Sudden Death and Exercise, Dr. Timothy Noakes writes:

“If just those sudden deaths occurring in athletes or people doing strenuous exercise are reported in the press, it is understandable why the public gets a distorted impression of the relationship between exercise and heart disease.”

Dr. Noakes warns that runners should not feel smug because they believe their elevated fitness levels automatically prevent heart disease.

“Regular exercise reduces the overall risk of sudden cardiac death in persons with low cardiovascular risks. But it may increase the risk of sudden death during extreme exertion for those who already have the type of heart disease that predisposes to cardiac arrest.”

Runners may be more at risk while they are out running – especially if they’re running a marathon – but for the rest of the day, their risk of keeling over is actually much lower than the non-fit general population.  Both men and women who try to make up for months of inactivity with a session of intense exercise are at greater risk for sudden heart attack than those who exercise on a consistent regular basis.

Dr. Noakes describes one study that followed the London marathon for 23 years. Over that time, there were seven cardiac deaths and five people who survived heart attacks during the race. The study found that the risk of death in the London marathon was one in 67,414 – “a risk which is comparable to many daily activities.”  Boston – the world’s oldest continuous marathon – has much better odds with just two recorded deaths in its 113-year history, which might make you think it’s safer for your heart to run Boston despite that killer “heartbreak hill” about 20 miles in.

Men in Ottawa (and elsewhere) might enjoy reading more on the link between exercise and heart disease.

See also:

The Haywire Heart: (a book about the link between endurance sports and heart disease by cardiologist/athlete Dr. John Mandrola with journalist Chris Case and cyclist Leonard Zinn)

Long Distance Running: Safe For Women’s Hearts?

Too Cold to Walk Today? Take a Heart-Smart Mall Walk!

Women’s Heart Health Advice: “Walk Far, Walk Often!”

Why Your Heart Needs Work – Not Rest – After a Heart Attack

What Prevents Heart Disease “Better Than Any Drug”?

Returning to Exercise (and Training) After Heart Surgery (THE best and most comprehensive overview on this topic I’ve seen yet, written by cardiologist and triathlete Dr. Larry Creswell; especially useful for heart patients who have been regular exercisers before their cardiac event and are wondering how to safely resume their daily routine)

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NOTE FROM CAROLYN:   I wrote more on cardiac risk factors in female heart patients in my book, A Woman’s Guide to Living With Heart Disease (Johns Hopkins University Press), you can ask for it at your local bookshop, or order it online (paperback, hardcover or e-book) at Amazon –  or order it directly from my publisher, Johns Hopkins University Press (use their code HTWN to save 30% off the list price).

© Carolyn Thomas www.myheartsisters.org

Note: information here is not intended as a substitute for medical advice