If you've been keeping up with the latest running news, you have likely heard about the recent deaths of runners at the London Marathon and North Carolina Rock-n-Roll Half Marathon.
Sadly, it is true. A 42 year old man passed at the London Marathon, and two men aged 31 and 35 passed in North Carolina while running the half. Even worse is that, not too much before that, a 16 year old girl passed running a half marathon in Virginia.
Shocked by all this bad news, I've been wondering the last couple of weeks how this could happen. You'd think that distance runners, when properly trained (which I know at least a few of these runners were), are in peak physical condition.
Interestingly, this week, I stumbled across this article. Some of the most interesting points are as follows:
“When someone suddenly dies in an athletic event, particularly in teenagers and those in their 20s and 30s – the most common cause is hypertrophic obstructive cardiomyopathy,” says Peter A. McCullough, M.D., M.P.H., a cardiologist at the Baylor University Medical Center at Dallas. “This is a genetic abnormality of the proteins used by heart muscle cells. The heart becomes abnormally thick in one area and when the heart pumps, it has trouble ejecting blood past that thick point. The heart becomes very, very thick – two to three times as thick as normal.”
HOCM causes unbalanced thickening (hypertrophy) in the walls of one chamber of the heart, the left ventricle, and particularly in the partition that separates the two ventricular chambers. In addition, cardiac muscle cells and the fibers within them that are responsible for coordinated contraction and relaxation of heart muscle appear microscopically to be quite disorderly, an arrangement appropriately called myofibril disarray. “This can be the setup for an abnormal, circular heart rhythm that can take off on its own, called a re-entrant arrhythmia, that can degenerate into full-blown cardiac arrest,” says Dr. McCullough. With the ventricles already having trouble filling with blood and ejecting it out, the abnormal heart rhythm develops, potentially because of less oxygen delivery to the heart muscle.
(3) Why this matters to runners
Says Dr. McCullough. “The reason why it happens with exertion, and, in particular with dehydration, is that there’s a decrease in the blood volume.” And as to why some deaths seem to occur at the end of the race, McCullough says, ”There’s still a lot of circulating adrenaline so the heart is pumping very, very hard, but there’s relatively little blood to fill it.” Moreover, blood pools in the legs when you stop running because there’s no longer the contraction of muscles that helps push the blood back up.
If you have time, read through the entire article that the above information comes from. Overall, it basically says that this condition is very rare, and can be detected by your doctor with some special diagnostic testing (if you have concerns - but be aware, the tests seem to be very expensive). So, really, you shouldn't let this scare you out of being active.
However, one interesting take away I found in the article was this:
To distinguish a separate type of damage from the above mentioned HCOM, the authors called a second type of damage Phidippides cardiomyopathy, after the Greek herald who died after running 175 miles in two days. Here, the heart doesn’t have asymmetric, localized thickening of the walls. Instead, the heart forms scar tissue that accumulates over time due to excessive and repetitive stretching of the heart ventricles pumping a remarkably large amount of blood during prolonged training and competitions.
For perspective, your heart is pumping about five liters of blood each minute as you’re reading this article. But when running near one’s maximal heart rate, you pump about 35 liters of blood per minute, a 700% increase in demand on the heart.
“If you go run for 20, 30, 40 minutes – that’s fine. The body’s kind of designed to do that,” says Dr. McCullough. “But when you go run for four hours straight, the heart chambers of about a quarter of individuals can’t tolerate it. The chambers start to dilate and the heart releases distress signals.”
And even more interesting:
Dr. Mandrola offered the following in closing:
"Please don’t ask where the upper limit of exercise is. I don’t think there is just one threshold. Individuals differ in their tolerance for stress. As physicians, though, we can emphasize to our patients what we know: It is possible to exercise enough to harbor an increased risk of arrhythmia and maybe even induce fibrosis. It’s worth noting that “superfitness” does not inoculate against heart disease. Do not judge a book by its cover. The engine should not be assumed healthy because the chassis looks sleek."
Dr. McCullough has likely run more marathons than any cardiologist studying this area. Between age 42 and 49, he ran a marathon in each of the 50 U.S. states. But now?
“I personally have retired from running marathons. I’m convinced there’s sufficient enough concern here that I just don’t want to pay the ultimate price of overdoing it. I’m enjoying the shorter races.”
In fact, Dr. McCullough had just finished a three-mile run before our interview. He said, “I feel great and I think one can get that great feeling that exercise delivers without going two, three, and four hours.”
Definitely some food for thought about working out versus over doing it.