More Exercise, More Plaque?

A study just published reveals a startling relationship that's the complete opposite to what most people would assume. So it found that the most heavily trained athletes were almost six times more likely to have plaque developing in their arteries than those who trained the least. Now that of course isn't the story that we'd expect. But what does this actually mean? Is exercise now bad for the heart? Well, to

answer that question, we need to go back to 2008 when German researchers examined 108 apparently healthy marathon runners. So these were men over the age of 50 who'd completed at least five marathons in the previous three years. The researchers found something completely unexpected. They compared this group with another group selected to have the same heart disease risk profile. So in other words, the group were the same in all of the relevant ways except for running marathons, but the marathon runners actually had a higher amount of hard calcified plaque buildup in their arteries. The study authors concluded that we've been making an unwarranted assumption that being a marathon runner means healthier arteries. The numbers here indicated that the opposite might be true and subsequent studies confirmed the signal. So in 2017, two landmark

papers were published backtoback in the journal of circulation. One found elevated plaque in UK masters endurance athletes despite lower traditional risk factors. Another looked at lifelong exercise volumes in active men around the age of 55 years old. 77% of those in the highest weekly exercise volume had plaque in their arteries compared to 56% in those with the lowest volume. But there was a silver lining. Researchers noticed that there were differences in the type of plaque present between the more and less active groups. So the more active groups plaque tended to be calcified. So this type of plaque is more stable. It's less likely to rupture and cause serious problems like heart

attacks. Then in 2023, the Masters at Heart Consortium, which is the same Belgian group behind this new paper that we'll look at in a moment, published the most comprehensive study to date. It included 191 lifelong endurance athletes, then another group with 191 late onset athletes, and then a separate group which were 176 active but non-athletic controls. And they were all screened to exclude cardiovascular risk factors. Partly what they found was now expected. So lifelong endurance athletes had significantly more plaque in the arteries. And then there was this bombshell. Unlike the findings from that last study, there was no silver lining. Troublingly, the lifelong endurance athletes, they did not have a less risky form of plaque than the healthy non-athletes. So what is going on here?

Why should endurance athletes accumulate more plaque in their arteries? And are they at higher risk of heart attacks? Well, lying at the center of this puzzle has been a heated debate that couldn't be solved until this latest study. The debate has been what drives this pattern in the studies that we've looked at. Is it a matter of pure training volume? So, do we increase plaque when we log too many accumulative hours on the bike or road over a lifetime, for instance? Or is it the intensity level that's the key risk factor instead? Well, the evidence has been ambiguous. Both sides have been able to make a case for their position. But there's been a weak point in the evidence. Almost all of the prior studies relied on self-reported training data. Participants were asked to recall the exercise patterns and then researchers turned this into metrics like met minutes a week. We get these numbers by multiplying activity intensity by activity time. And the end result looks satisfyingly precise. But in most of these studies, it's a metric based on surveys and memory, not actual measurements. And we found that recall data doesn't correlate with actual measurements of activity very well. But

this new study did something different. It tracked participants using wearable monitors in addition to gathering the usual self-reported data. So, the researchers calculated training load by multiplying training duration by the level of intensity measured by heart rate. And that's how they derived the shocking number that this video started with. Those with the highest intensities had almost six times the risk of developing plaque. Interestingly, when they looked at the same participants using the conventional self-reported data, the old method, in other words, the association essentially vanished. And this shows how significant the choice of measurement can be. So, what

does this study tell us about the debate? Is intensity or volume the main driver of increased plaque? Well, interestingly, highintensity [snorts] exercise alone without lots of volume, it wasn't linked to high levels of plaque buildup. On the other hand, high volume showed stronger connections with pluck when it included large amounts of highintensity training. But what does this all actually tell us? Is high exercise volume, especially when combined with high intensity, dangerous for our heart health or not? Well, the answer is a bit nuance, so bear with me here. First, it's important to notice that the study found more plaque, but it did not find more heart attacks. The plaque in the athletes arteries, they were found because they were looking for it using a CT scanner. It wasn't causing obvious symptoms or problems. There's no data here showing that the athletes doing the most training were having more heart attacks. Second point, it's important to keep in mind who we're comparing the most active athletes to. So, the comparison group, they're not couch potatoes. They're moderately active. So, we're looking at a set of people within the study who are all in relatively good shape. The study doesn't tell us about how athletes in the high end of the intensity and volume spectrum compared to people who aren't active at all. That surely would give us a very different picture. We'd expect the sedentary individuals to have far worse health outcomes. But let's return to the first point. The study found more plaque with high volume athletes, but it did not find worse health outcomes. And that is really the key thing that we want to know. Does the greater plaque burden for the high volume athletes lead to problems or not? And to get a better answer to this question, we need to turn to another study. And this is where it gets genuinely interesting. So, a study with over 21,000 participants, they were followed up for 17 years and it found that high volume exercises were more likely to have elevated measures of plaque, which again matches the pattern, but crucially, they were not more likely to die from heart disease or other causes. So far, then here's what the data seems to be showing. High levels of intense exercise increase plaque volume, but the additional plaque doesn't seem to correlate with increased risks of death from heart attacks or other causes for these people who exercise. And when it comes to overall health and overall death rates, there still seems to be an advantage gained by those with very high training volumes. So, it appears that the downsides to high training volumes when it comes to heart health is offset by other benefits of exercise. But let's

try and get practical for a second here. What does all of this actually mean for us when it comes to exercise? Well, exercise is still the most powerful tool that we've got for promoting healthy, long lives. There's nothing in these studies that we've looked at that overturns that. And the data that we've just looked at reinforces that point. Exercise, it still lowers all cause mortality. This is a classic case where it's far better to focus on hard outcomes like heart attacks and deaths rather than markers like plaque scores. Equally, however, fitness is not an immunity. When we're amongst the most active, this doesn't give us blanket protection from heart disease. If we're in this group of very high volume athletes, these studies suggest that we could still have plaque building up in our arteries. And the right response is not to stop exercising. Instead, it's just that we don't want to assume that just by being fit means that we don't have to worry about other cardiovascular risk factors. So, personally, I exercise because the evidence for its benefits is overwhelming. And I also started taking lipid lowering medications a few years ago, even though I'm only 34 and without any other risk factors. I want to avoid plaque formation as much as possible, especially with this exercise data. It's not a matter of either or, but both. And I aim to get my LDL cholesterol below 50 to 60 milligs per deciliter. And that is due to the PISE study. And you can get your own personalized health plan to discuss with your doctor here. So for me, I'm male. I'm 183 cm. uh my weight is 83 kg. Uh and then before I went on to cholesterol lowering medications, my LDL cholesterol was 1. 9. Uh so in US units that is 73. So a bit higher than what was ideal. So the calculator here will tell me that I should consider starting a statin medication. So I started pravisatin at night. That wasn't quite enough to get me to below 50 to 60 millig per deciliter. So then I needed to add a zetam. The calculator gave me those recommendations as well. Now, for most people, it's a bit of a shock to learn that exercise might have a downside when it comes to blood vessel health, but health is full of surprises like that. And there's a popular supplement that carries a risk of damaging our blood vessels. And I find my patients at the clinic almost never know about this. So, make sure to check out this next video here to make sure that you're not unintentionally doing yourself harm.