Can exercise trigger a heart attack?

11 Jul

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 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 not strong enough to shovel wet, heavy snow.

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

fixx_cp_2857454James 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:

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© 2009 Carolyn Thomas www.myheartsisters.org

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

7 Responses to “Can exercise trigger a heart attack?”

  1. Emo January 8, 2010 at 5:51 pm #

    You have a great writing style. Many thanks for this solid information on exercise and heart attacks.

    Like

  2. Jack December 24, 2009 at 8:51 am #

    This is good news for those of us who actually like shovelling snow. Yes, there actually are a few of us out here.

    I’ve always thought that if you keep relatively active and fit all year long, then snow shovelling, done correctly as your illustration shows, just adds to your regular cardiac workout in a GOOD way. I always feel like I’ve had a good solid workout, better than the gym, after clearing our long driveway here in New England on a sunny morning after an overnight snowstorm. Nothing like a steaming cup of coffee after that kind of outdoor workout plus the satisfaction of a job well done.

    And now I can even stop worrying about my heart while I’m at it. Thanks for this comprehensive explanation. I’m forwarding this article on to my couch potato friends, plus I’m subscribing to your two excellent website updates.

    Merry Christmas to you and your family.

    Jack

    Like

  3. Shovelling in Ottawa December 8, 2009 at 3:03 pm #

    Great article, thanks. My uncle had a heart attack while shovelling snow three years ago. At the time it was an awful shock we all thought it was the exercise that day that killed him but we later learned that he had serious heart issues for decades so I suspect that this theory is correct; that an “underlying” heart condition was there all along like a time bomb and the snow shovelling was all it took to get the bomb to go off but was not the simple cause of his death.

    This experience scared the whole family; we all got tested and began to seriously identify existing risk factors for the first time because now we know that this can really happen to anybody no matter how healthy they look on the outside. My uncle was “healthy” but led a sedentery life and smoked so now we believe that it was the sudden exercising that was the last straw for his poor heart but not the exercise itself. We have now become a family of fitness maniacs now in the past three yrs. Two of us have taken up competitive swimming, one squash player, two rec league hockey players and the rest are all walking daily no matter the weather, and yes we still shovel snow but now are in good shape for it unlike my uncle.

    Like

  4. Pharmacist August 5, 2009 at 9:25 am #

    Thank you. I was hoping to get out of shovelling the walk today, but no luck after reading this . . .

    Like

  5. Carolyn July 13, 2009 at 7:01 am #

    Hi Lew! You’re working 12 hours a day? That in itself will ‘zap’ your energy, with or without the added burden of your meds. It’s a common reality – too exhausted to exercise, which is the very thing that would help increase energy level!
    Thx
    C.

    Like

  6. lewp July 12, 2009 at 9:57 pm #

    Great article. I’m hooked on your website, Carolyn.
    One thing I would like to say here is I believe medication is a factor here as well. After my heart attack in July of 2008, I was prescribed Lipitor, and then Crestor as statin drugs to control cholestrol. I was enrolled in a cardiac care program and was scheduled to work out for 30 minutes per day, 3 days per week. I couldn’t do it. That 30 minutes coupled with working for 12 hours per day zapped my energy. I attribute it to the prescription drugs. I would love to be able to work out to help lower the bad cholestrol. Perhaps new medication will allow me to do that with out any side effects.

    Like

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  1. Walking As Exercise - December 28, 2009

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