How to ensure physical activity helps you live longer, instead of sending you to an early grave.
Around 10 or so years ago, there was a thankfully short-lived anti-cardio fad where certain Internet ‘experts’ were discouraging people from doing endurance exercise.
Their rationale for this terribly misguided recommendation was the claim that endurance exercise damages your heart.
Like many bad recommendations, this claim contains a kernel of truth.
The content below was originally paywalled.
A 2012 Mayo Clinic Proceedings paper made waves when it postulated that “long-term excessive endurance exercise” could cause the kind of heart damage that increases the risk of arrhythmias (bold emphasis added).
The authors of that paper wrote:
“Emerging data suggest that chronic training for and competing in extreme endurance events such as marathons, ultramarathons, ironman distance triathlons, and very long distance bicycle races, can cause transient acute volume overload of the atria and right ventricle, with transient reductions in right ventricular ejection fraction and elevations of cardiac biomarkers, all of which return to normal within 1 week.” (Bold emphasis added)
So if everything is hunky dory a week later, what’s the problem?
“Over months to years of repetitive injury, this process, in some individuals, may lead to patchy myocardial fibrosis, particularly in the atria, interventricular septum, and right ventricle, creating a substrate for atrial and ventricular arrhythmias. Additionally, long-term excessive sustained exercise may be associated with coronary artery calcification, diastolic dysfunction, and large-artery wall stiffening. However, this concept is still hypothetical and there is some inconsistency in the reported findings.” (Bold emphasis added)
Despite the possibility that extreme exercise may cause heart damage in some individuals was still a hypothetical one, the anti-cardio activists had no qualms about decisively warning people away from all endurance exercise - as if every 45-minute session on the treadmill was going to permanently scar your heart and eventually cause you to keel over from fatal arrhythmia.
What these commentators didn’t mention were the parts of the 2012 paper that said things like:
“A routine of regular exercise is highly effective for prevention and treatment of many common chronic diseases and improves cardiovascular (CV) health and longevity.”
“People who exercise regularly have markedly lower rates of disability and a mean life expectancy that is 7 years longer than that of their physically inactive contemporaries.”
“a 15-year observational study of 52,000 adults found that runners had a 19% lower risk of all-cause mortality compared with nonrunners, with U-shaped mortality curves for distance, speed, and frequency. Running distances of about 1 to 20 miles per week, speeds of 6 to 7 miles per hour, and frequencies of 2 to 5 days per week were associated with lower all-cause mortality, whereas higher mileage, faster paces, and more frequent runs were not associated with better survival.”
The idea you should be forming right about now is, not to shun endurance exercise, but to avoid excessive endurance exercise.
Of course, bold, definitive and sensationalist claims make much better clickbait than more moderate presentations that relay both sides of the story. And so, not to be bothered with such trivialities as telling the whole truth, the anti-cardio commentators simply found more studies to misrepresent.
They cited a 2008 German study involving 108 apparently healthy male marathon runners aged 50–72 years who were followed for a mean period of 21 months. The participants had completed 14–42 marathons, had started marathon running between 7–16 years ago, and ran 45–65 km over five days per week throughout the year.
A coronary artery calcification (CAC) score of zero (ideal) was more frequent in marathon runners than in age-matched controls, but was similar when compared with a subgroup of controls with similar Framingham Risk Scores.
The Framingham Risk Score assesses one’s 10-year risk of coronary heart disease based on age, sex, blood pressure, smoking and, of course, the largely useless CHD markers that are LDL and HDL cholesterol.
Overall CAC score distribution was similar in marathon runners and age-matched controls, with similar rates of 100+ CAC scores in these groups. However, higher rates of CAC scores over 100 were seen in marathon runners when compared with FRS-matched controls (36% vs. 22%, respectively).
Late gadolinium enhancement (LGE) is a measure of myocardial replacement fibrosis (‘scarring’ of the heart). It indicates previous damage and is strongly associated with adverse cardiac events.
So it was a concern when the German researchers found the prevalence of LGE in runners was higher than that in age-matched control subjects (12% vs 4%).
CAC values and number of marathons (but not FRS) independently predicted the presence of LGE.
During the mean 21-month follow-up, 4 of the runners experienced coronary events (2 sudden coronary events and 2 revascularization procedures). All four had significant arterial disease, with CAC scores ranging from 128 to 874.
One of these runners had a coronary event 7 km into a 10 km race, and had to be resuscitated. Coronary angiography revealed he had significant plaque (causing 80% narrowing) in each of the three main coronary arteries. Needless to say, his arteries were not in good shape.
Another of the four suffered an event during moderate exercise, and again was successfully resuscitated.
This, said the anti-cardio commentators, was further proof that endurance exercise is bad for the heart.
But let’s look at these findings from a more balanced perspective.
Four out of 108 runners suffered a coronary event - that’s a mere 3.7% percent of the sample.
While CAC and FRS scores were compared to a control group, event rates were not. So we don’t know how many control subjects suffered coronary events during the same period.
Most of the men had begun running in mid-life; 4.6% were current smokers, while 53% were former smokers (concurrent rates among controls were 28.4% and 42.1%, respectively). Three of the four runners who suffered coronary events during the study were former smokers (the other reported never smoking).
Did the runners live formerly unhealthy lives that caused cardiovascular damage that was exacerbated by frequent running? Or did running in fact reverse some of this previous damage?
The nature of the study was ill-equipped to answer these questions, so let’s look at some more studies that place the risk of exercise-induced CVD events in proper perspective.
Marathon Running and Cardiac Arrest
In a 2012 paper, researchers from Harvard Medical School and a number of other prominent university hospitals reported the incidence of cardiac arrest associated with marathon and half-marathon races in the US between January 1, 2000, to May 31, 2010.
Of 10.9 million runners, 59 suffered a cardiac arrest, 42 of which were fatal. The mean age of those suffering an event was 42 years, and 51 of the victims were male.
This gives an incidence rate of 0.54 per 100,000 participants. The incidence rate was significantly higher during marathons than during half-marathons (1.01 vs 0.27, respectively) and among men than among women (0.90 vs 0.16).
Among the 31 cases with complete clinical data, initiation of bystander-administered CPR and an underlying diagnosis other than hypertrophic cardiomyopathy were the strongest predictors of survival.
To further place these results in perspective, statistically you have more chance of being hit by lightening than suffering a heart attack during a marathon. The study results equate to a 1 in 184,745 occurrence of cardiac arrest over a decade, which compares quite favorably to the oft-cited 1 in 15,000 odds of being struck by lightening in any given year.
Climbing Their Way to Longevity
Most people would consider pro cycling to be a pretty extreme endeavor. Big stage races like the Tour de France, Giro d’Italia and the Vuelta a España involve three weeks of racing, with only 2 or 3 days’ rest. Those who complete these events will have covered thousands of kilometres, a significant portion of them ascending tall mountains where “backing off and taking it easy” still means working hard.
So if endurance exercise was bad for the heart, pro cyclists should be dropping dead like nobody’s business.
To the contrary, follow-up of former pro cyclists who competed in the Tour de France between 1930 and 1964 found they had an average 17% (8 years) increase in longevity compared to the general population.
A more recent sample of French participants who competed in the Tour de France from 1947–2012 found a 41% lower mortality risk.
It’s not just pro cyclists who push the envelope yet enjoy greater longevity. A 2018 analysis found the first 20 known 4-minute milers exceeded life expectancy by an average of 12 years.
That’s impressive.
More broadly, a recent review found positive longevity results for many sports, excluding Sumo wrestling, handball and volleyball.
This, of course, will be of little consolation to the small percentage of seemingly fit individuals who nevertheless do suffer a coronary event. Before we look at what can be done to reduce risk in these folks, let’s take a look at a combination that does markedly increase the risk of heart attack and sudden death.
Lack of Fitness + Sudden Exertion
Even highly fit people perform warm-ups prior to weight-training or intense cardio workouts. A proper warm-up allows your body to gradually increase blood flow, muscle temperature and elasticity. You can’t go from a sedentary state to a state of high exertion without some sort of transition phase, and not expect adverse outcomes.
So what happens when people not accustomed to physical exertion do just that?
Bad things.
It is a well-established phenomenon that sudden exertion in sedentary or unfit individuals greatly increases the risk of a sudden coronary event.
Almost thirty years ago, during a trip to the US, I stayed with some gracious hosts in Rochester, in upstate New York. It was the first time I’d ever physically experienced snow. It was a novel experience for about an hour, after which I never wanted to see snow again. Throwing snowballs is fun; trudging through snow to get anywhere and removing the white pyramid that forms every night on your car roof … not so much. The grey-brown sludge that forms when snow and road grime mix isn’t exactly the stuff of postcards, either.
Turns out these were among the more trivial concerns of local residents. My hosts explained to me that every winter, heart attack rates jumped dramatically as men got out every morning and shoveled snow to clear their driveways.
A 2017 paper investigated the association between snowfall and hospital admission or death due to heart attack in Quebec, Canada during 1981–2014. It confirmed the likelihood of hospital admission and especially death due to heart attack was increased the day after a snowfall among men but not among women.
A 2020 paper in Circulation reported:
“Snow shoveling has repeatedly been associated with increased cardiovascular events soon after major snowstorms, probably because it can elicit higher rate-pressure products than maximal treadmill testing and is often performed by unfit individuals with known or occult CAD. Also, some cardiac patients develop angina at lower rate-pressure products during exercise in cold temperatures, possibly because of cold-induced vasospasm. Ventricular arrhythmias, coronary plaque rupture and ST-segment–elevation MI, and subacute stent thrombosis have also been reported with snow shoveling.” (Bold emphasis added)
Snow shoveling by sedentary, older men combines several highly unfavorable factors: Lack of fitness or even preexisting cardiovascular disease, very cold temperatures which cause vasoconstriction, and sudden heavy physical exertion.
That combination is a heart attack waiting to happen.
The increased risk is so great that a Cleveland Clinic cardiologist advised in 2021 that if you have more than one medical condition or are over the age of 55, it’s best to get someone else to shovel for you.
“Particularly people that have multiple medical conditions such as coronary artery disease or hypertension, or maybe they have overweight or obesity and don’t get a lot of physical activity — it’s not worth it to risk your heart,” said Luke Laffin, MD.
“I think hiring the kid down the street to do it is a great idea,” he said.
Just make sure the poor kid hasn’t had the Modernapathy or Pfizercarditis shots.
The increased risk of heavy exertion isn’t just limited to those living in snow-affected areas.
A 1993 paper by Harvard researchers reported on interviews conducted with 1,228 patients conducted an average of four days after suffering myocardial infarction heart attack). Of these patients, 4.4% reported heavy physical activity within one hour before the onset of their MI. Symptoms usually began during the activity.
The researchers estimated a nearly six-fold relative risk of MI in the hour after physical exertion.
The risk increased as one’s habitual physical activity level decreased. Among people who usually exercised less than one, one to two, three to four, or five or more times per week, the relative risks were 107, 19.4, 8.6, and 2.4, respectively.
So those who exercised less than once per week had an average 107-fold increased risk of MI in the hour after heavy physical exertion, while those who exercised five or more times per week had a 2.4-fold increased risk of MI within an hour of heavy exertion.
That 2.4-fold increased relative risk among the most active participants needs to be weighed against the overall benefits of high activity levels. In the Nurses’ Health Study and Health Professionals Follow-up Study, the most physically active cohorts demonstrated 7- to 8-year gains in life expectancy during up to 34 years of follow-up.
What to Do
Overall, endurance exercise is a boon to health and longevity.
Heavy physical exertion, however, increases the acute risk of heart attack, especially in those who do little to no regular exercise.
So here are some precautions to keep in mind.
Start Lightly and Progress Gradually
If you are currently sedentary, the first thing to do is get active. Start off slowly, and gradually increase your physical activity levels.
Get Expert Advice
If you have cardiovascular disease or currently exhibit symptoms indicating increased CVD risk (overweight/obesity, high blood pressure, irregular heartbeat, etc), then I’d strongly advise seeking out a cardiologist or other professional familiar with exercise prescription for those with or at risk of CVD.
Don’t Ignore Warning Signs
Symptoms of an impending cardiovascular event often begin during the activity, so if you start feeling chest pain, dizziness or other symptoms of heart attack or stroke during exercise, then stop and let someone know. If the symptoms are severe, call an ambulance. Embarrassment is far less deadly than an untreated heart attack or stroke.
Avoid Extreme Temperatures
Wherever possible, avoid exercise or physical exertion in extreme temperatures. Both very hot and cold weather increase the risk of heart attack. Exercising in the heat also increases the risk of dehydration.
Always Warm Up
Unless it’s an emergency situation requiring immediate action, always warm up before exercise or strenuous physical activity. The older and less fit you are, or the colder the ambient temperature, the longer and more thorough your warm-up should be.
If you don’t have time to do a warm up, then you don’t have time to do a workout. It’s that important.
Avoid Exercising in a Hypoglycemic State
Another important but oft-ignored risk for heart attack is hypoglycemia (low blood sugar).
Among the many unwanted effects of hypoglycemia are a greatly increased output of the catecholamines epinephrine and norepinephrine, which can induce vasoconstriction and platelet aggregation. That’s not ideal during exercise, when you need increased blood flow to the muscles and heart.
Hypoglycemia-induced catecholamine release has also been linked to hypokalemia, in turn linked to severe ventricular arrhythmia and sudden death. This progression of events has been suggested as an explanation for the “dead in bed” syndrome of patients with type 1 diabetes.
Needless to say, hypoglycemia is not an ideal state to be in during exercise. But in the absence of carbohydrate intake, that’s exactly the state many endurance exercisers will find themselves in after 45 minutes or so of continual activity. It’s around the 45 minute mark that muscle glycogen levels become heavily depleted during continuous and vigorous activity, forcing the body to source sugar from the bloodstream. Blood sugar constitutes a very short-lived supply of glucose, which is why professional athletes almost invariably utilize carbohydrate drinks and gels during events lasting 90 minutes or more.
An article discussing how much carbohydrate to consume during exercise is available free to paid subscribers here.
This is yet another reason I’m not keen on low-carb and intermittent fasting/time-restricted eating regimens for serious exercisers and athletes. Little benefit comes from pushing yourself while running on an empty tank.
Yes, I know about the arguments claiming fasted cardio increases the portion of fat you use as fuel. When you’re lying in a hospital bed with a huge scar down the middle of your chest, no-one is going to care whether you managed to burn a few extra grams of fat during a morning cardio session.
Avoid Overtraining
This topic is worthy of not just a separate post, but an entire book. Suffice to say, more is not always better. Sometimes it’s downright harmful.
Your heart is a muscle, one that is already working 24/7. When you lie in bed at night, the “show muscles” of your limbs and torso get to relax; your heart enjoys no such luxury.
Don’t train balls-to-the wall, day in, day out. This applies to cardio and strength training. Periodize your training so that it includes days or even weeks of reduced intensity.
Don’t train through illnesses, when you are tired, or when you are injured. Doing so is more dumb than dedicated.
Don’t emulate the voluminous training routines of elite athletes or athletes who consume performance enhancing drugs.
In other words, use commonsense and don’t bite off more than you can chew.
Avoid Steroids
Speaking of PEDs, while there is little evidence of harm from judicious use of testosterone cypionate or enanthate (the choice for TRT in men), steroids like stanazolol and trenbolone have repeatedly been linked to cardiovascular harm in the literature. Steroids can also have other unwanted effects; trenbolone (aka “tren” and “fina”) especially has a reputation for causing increased aggression, violent behavior, as well as “impulsivity regulation” issues (i.e, doing crazy stupid stuff without first thinking of the consequences).
Tren has even established something of a reputation for causing sexual deviancy.
Conclusion
Physical activity is the closest thing we have to an elixir of youth. That doesn’t mean you can abuse it. Be smart and realistic in your training goals, progress gradually, and back off when your body tells you to.
Wherever possible, avoid strenuous physical activity in the absence of a warm-up.
And if you’re on the wrong wise side of fifty, pay someone else to shovel the snow from your driveway.
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