I’ll admit right from the top of this piece that I’m an exercise nut. I’ve been a long-distance runner from my early teens and a long-distance swimmer in the pool and the ocean for decades. I’ve always thought that meant I was in good health, but now, as the exercise freak baby boomers like me age into our 60s and 70s, there’s recent data that suggests otherwise. There’s more and more data coming out in the medical literature showing that there are some damaging effects on our bodies from accumulating all those thousands of miles and shedding gallons of sweat. It’s not just joint and ligament issues; a new study published a few months ago on aging athletes documented some other real concerns. They reported a significantly higher risk of life-threatening arrhythmias (abnormal heart rhythm) like ventricular tachycardia in lifelong athletes because of risks of structural heart disease, and this can lead to a higher risk of sudden death. Aristotle used an eloquent and thought-provoking analogy of life as a banquet, “It is best to rise from life as from a banquet, neither thirsty nor drunken.” His obvious point is that moderation is the key and there are limits to even good things. Since it turns out that too much of a good thing, exercise, can have a downside too, let’s take a deeper dive (pun intended) into these new concerns.
These recent data show that older endurance athletes face about 4X the risk of sudden cardiac death compared to moderate exercising adults. Although the overall risk is still pretty small, the incidence of exercise-related ventricular arrhythmias was 4/10,000 hours of exercise compared to a ventricular arrhythmia incidence of 1/10,000 hours in study participants who did only moderate amounts of exercise. This is probably related to a much higher rate of myocardial fibrosis (scar tissue in the heart muscle), which accumulates over decades, in older endurance athletes. Fibrosis and scarring in the heart are bad things for both muscle strength and pump function, leading to congestive heart failure and high blood pressure in the lungs (pulmonary hypertension) and shortness of breath along with permanent damage. Scarring in the electrical cables of the heart (conduction system) was also documented in this study group. This can lead to a very slow heart rate and even end up with something called “complete heart block,” which is another potential cause of sudden death. A review published just last month stated, “[an] athlete’s heart featuring resting bradycardia (slow heart rate) has traditionally been viewed as a benign adaptation and a metric of health. However, emerging evidence associates endurance training with an increased risk of clinically significant cardiac electrical dysfunction. Exercise-induced intrinsic electrical system remodeling is a physiological adaptation mechanism that, under certain conditions, can cross a threshold to become a pathological cause of clinical dysfunction.” Yeah, real fancy talk for how too much of a good thing can sometimes be bad.
It seems counterintuitive, but even so, recent studies in lifelong male athletes aged 40 years and above also show a higher prevalence of coronary artery disease that leads to recurrent small (subclinical) heart attacks. It’s even possible to find evidence of cardiac damage (elevated troponin ‘I’ and troponin ‘T’) in blood tests of distance runners after races. This correlates with a higher coronary plaque burden and even further worsening myocardial fibrosis when compared to healthy controls. All of those miles can ultimately lead to enlarging of the heart that imposes still more chronic coronary stresses on cardiac circulation and heart muscle.
This is substantiated by another review published a few years back appropriately titled, “The Athlete’s Heart—The more the Merrier?” that concludes that the “athlete’s heart is characterized by enlargement of cardiac chambers due to physiological adaptations to prolonged and intense endurance physical stress.” This kind of change in heart size and function is called “cardiac remodeling,” and a good review from a few months ago summarized the issues. “Recent data have raised concerns that long-term endurance exercise participation is associated with potential structural, functional, and electrical remodeling, a condition known as ‘aging athlete’s heart.’” We’ve covered numerous treatments for coronary disease and there are more all the time. The electrical abnormalities associated with this condition are also curable but require placement of a permanent pacemaker to take over the conduction system of the heart. The good news is that newer pacemaker technology for this condition has become extremely sophisticated and reliable.
There are other issues with heart rhythms in aging exercise warriors; atrial arrhythmias like atrial fibrillation (AF) , which we’ve talked about before in these pages, are more common in older distance athletes. A multi-center study from the British Journal of Sports Medicine confirms that “older male endurance athletes exhibit an increased risk of atrial fibrillation.” The study covered male athletes who were all over 50 years and exercised ≥10 hours/week for ≥15 years. Atrial fibrillation leads to loss of heart function and heart failure, since 30% of the pumping capacity of the heart depends on coordinated atrial and ventricular action. It can also lead to intravascular clotting, which is a common cause of stroke, peripheral limb loss, and GI injuries, all of which can be fatal. A study in the Danish population documented that 20% of patients with AF suffered a stroke. It also points out that AF is more than 5X more common in aging distance athletes than in the general population. AF is rightly considered a disease of older patients—but not always. The British Medical Journal published a review a few months ago on an association of AF in children who participated in intense physical exertion. So, there’s something associated with very aggressive levels of physical training that can lead to arrhythmias in both the atrium and ventricle in both adults and kids.
There’s no doubt that exercise has multiple benefits to our health and well-being, both physical and mental. Release of that “feel-good” chemical, endorphin, in the brain during a good, vigorous workout has been known for years. Everyone has had the experience, and I can say from years of personal experience with long-distance running that you can feel really good after a long run and a good sweat. We’ve talked about these brain chemicals before in this space, but also pointed out that too much of these feel-good neurochemicals is not good either. Perry Wilson, MD, from Yale Medical School hit the topic of moderation on the head in an article talking about drinking; it’s great advice about alcohol but applies just as well to our topic today. Paraphrasing his quote, “So… how much should you exercise?” the answer is probably just enough.Just enough to find the enjoyment from exercise without finding regret.Just enough to unwind without unraveling.Just enough to take the edge off without losing your edge. So—get your steps in and exercise frequently, but don’t overdo it, and as always, FLY SAFE.
