A new study has raised the possibility once more that sustained endurance training may paradoxically worsen coronary atherosclerosis. This study may highlight the importance of emphasizing balance over excessiveness. In our Western society, it’s becoming more and more prevalent to live an excessive lifestyle.
In the Master@Heart trial, lifelong endurance athletes exhibited more coronary plaques than fit, healthy adults with a comparable low cardiovascular risk profile, including more noncalcified plaques.
The work was presented on March 6 at the recent World Congress of Cardiology (WCC) 2023 and American College of Cardiology (ACC) Scientific Session.
The European Heart Journal also immediately published it online.
“We routinely find that lifelong endurance athletes have increased plaque burden. No matter the type of plaque—calcified, mixed, noncalcified, in the proximal segment, or causing more than 50% stenosis—this is true, said Ruben De Bosscher, MD, of the Catholic University of Leuven in Belgium, at the conclusion of his presentation.
According to the researchers, there may be a “reverse J-shaped” dose-response association between exercise and coronary atherosclerosis based on all available data.
The worst thing you can do, according to De Bosscher, is absolutely nothing. It appears that you start to feel the benefits as soon as you engage in some exercise, even if it’s only brisk walking or jogging for up to three hours a week. Following then, the burden of coronary plaque tends to rise.
Given that it is well known that endurance athletes exhibit significantly improved mortality, Michael Emery, MD, co-director of the Sports Cardiology Center at Cleveland Clinic, who moderated the discussion of the study at the ACC session, questioned how this information should be translated into recommendations for the general public.
De Bosscher answered, “That is a very good question. “Certainly, there are fewer incidents and worse outcomes among endurance athletes, but this is true across the board, including among individuals who are unhealthy and do not exercise.
“The question is, do we see the same association if we simply look at healthy people who exercise, but at different levels?” said he. There is growing evidence that there may be a point of reduced returns, and at some point, endurance athletes experience an increase in cardiovascular risk.
De Bosscher continued, “One of the important results here is that despite leading a highly healthy lifestyle and engaging in vigorous exercise, no one is immune to coronary atherosclerosis. It appears that people who exercise moderately—up to roughly 3 hours a week—benefit the most from doing so.
Theheart.org | Medscape Cardiology’s Emery stated in a comment: “This continues to be a ‘hot topic,’ however I continue to be disappointed, given a lack of hard outcomes, and I worry about the erroneous take-home message, that too much exercise will cause more harm than benefit.”
He continued, “The higher your fitness, the better the outcome,” and he would not advise individuals to quit exercising regardless of their calcium level.
The study “does clearly indicate that exercise does not make you immune from heart disease,” he conceded, adding, “which is a message a lot of athletes need to hear, honestly.”
The problem we have in the US and other industrialized countries is not too much exercise, but rather that most individuals don’t exercise at all, according to Paul D. Thompson, Hertford Hospital, Connecticut, who also provided a comment for theheart.org | Medscape Cardiology.
The Master@Heart study, he said, “made an essential addition” to the area.
According to earlier studies, lifelong endurance athletes tend to have greater cholesterol accumulation in their coronary arteries than one may anticipate. Yet this study demonstrates that the plaques in endurance athletes are not quite as benign as we had previously believed. Prior studies had revealed that the majority of the deposits in endurance athletes were the safer sort of highly calcified plaques.
He continued, “Despite these findings, it’s quite evident that endurance athletes live longer than other people, so it’s unclear what this means. The question is, “Do they live longer because they exercise more or because they are simply more resilient than the rest of us?”
He doesn’t think the findings should be used to support the idea that endurance training is harmful. “The evidence supporting that isn’t very strong. This coronary artery finding is present. We lack data on the results.
It doesn’t appear like you need to engage in a lot of severe sport, he continued, in order to reap the cardiovascular advantages of exercise, he added. According to every study, the persons who increase their exercise from very little to moderately intense get the biggest health benefits. It then appears to plateau.
Thompson emphasized that the most recent physical activity recommendations in the US call for 75 to 150 minutes per week of strenuous activity, such as running, and between 150 and 300 minutes of moderate exercise, such as brisk walking.
Nonetheless, he does not think that this research should discourage people from engaging in endurance exercise, pointing out that many people perform intense, rigorous exercise for reasons other than their cardiovascular health.
“I say go ahead and do it,” Thompson continued. “If individuals want to do more, whether for competitive reasons or if it makes them feel good, I say go for it. “You ought to relish life. Yet, it appears that even more extreme levels of exercise don’t seem to be of any benefit to you if you are miserable when engaging in high levels of endurance exercise for your health. Does it hurt you in any way? We don’t yet have enough data to draw that conclusion.
Study by Master@Heart
De Bosscher mentioned in his presentation that earlier research had found that athletes had higher calcium scores and more coronary plaques than control subjects. However, the atherosclerotic lesions seen in athletes were mostly calcified plaques, which were thought to be more stable and less likely to rupture, as opposed to nonathletes, who had more mixed plaques, which were thought to be less stable and more likely to rupture.
He emphasized, however, that these studies had limitations, including the fact that they included some people with other cardiovascular risk factors, such as smoking and use of statins or antihypertensive medications; they did not always evaluate the relationship between exercise and coronary atherosclerosis in a dose-response relationship; and while they reported the relative difference in plaque types, they did not report the absolute prevalence in calcified, noncalcified, and mixed plaque.
The Master@Heart study set out to investigate this issue in greater detail.
The observational cohort study assessed coronary atherosclerosis in 176 healthy nonathletes who did no more than 3 hours of exercise per week, 191 lifetime master endurance athletes, 191 late-onset athletes (endurance sports started after age 30 years), and 191 late-onset athletes. The cardiovascular risk profile of each participant was minimal, and they were all male. In each of the three categories, the median age was 55.
To measure fitness, maximum oxygen uptake (VO2max) was used. A larger percentage of predicted VO2max was found in lifelong and late-onset athletes than in non-athletes (159 vs 155 vs 122).
Age, weight, blood pressure, cholesterol levels, and A1C levels did not significantly differ across the three groups. Both groups of athletes were noticeably thinner (body fat percentages 14% to 15%), but the control group had a healthy BMI and body fat percentage (19%).
The lifelong and late-onset endurance athletes engaged in similar activities, primarily cycling and running. Compared to the control group’s one hour of exercise per week, the endurance athletes reported working out an average of 10 to 11 hours each week. Only 22% of the control group said they did no exercise at all; the rest said they ran, cycled, or played non-endurance sports like tennis.
Findings showed that compared to control subjects, lifetime athletes had a greater total coronary plaque burden as measured by segment stenosis and segment-involvement scores (between-group difference, 0.86 and 0.65, respectively).
Compared to a healthy non-athletic lifestyle, prolonged engagement in endurance sports was linked to having one or more of each of the following characteristics compared to control persons:
>1 coronary plaque (95% CI: 1.17 to 2.94; OR: 1.86)
>1 proximal plaque (95% CI: 1.24 to 3.11; OR: 1.96)
>1 calcified plaque (95% CI: 1.01 to 2.49; OR: 1.58)
More than one calcified proximal plaque (OR: 2.07; 95% CI: 1.28–3.35)
>1 noncalcified plaque (95% CI: 1.12 to 3.40; OR: 1.95)
More than one proximal noncalcified plaque (OR, 2.80; 95% CI, 1.39 – 5.65)
>1 mixed plaque (95% CI: 1.06 to 2.99; OR: 1.78)
Lifelong athletes were more likely to have 50% stenosis in any coronary segment than late-onset athletes did (OR, 2.79; 95% CI, 1.20 – 6.50) and 50% stenosis in a proximal segment than late-onset athletes did (OR, 5.92; 95% CI, 1.22 – 28.80).
In all groups, vulnerable plaques—those with more than two high-risk features—were rare, but a lifetime of physical activity was linked to a decreased prevalence (OR, 0.11; 95% CI, 21 0.01 – 0.98).
The Master@Heart study is the biggest and most thorough study to evaluate the dose-response association between intense endurance exercise and coronary atherosclerosis, the researchers write in their article published in the European Heart Journal.
According to their findings, highly trained endurance athletes do not have a more benign plaque composition, which would account for their lower incidence of cardiovascular events compared to non-athletes.
“Our data open the question of whether coronary events are truly less common in this high-end exercise group, and if that is the case, on what explains the paradox,” they write in their conclusion. Studies on the influence of physical activity in the top range are lacking. At the higher end of the endurance training continuum, more long-term research is unquestionably required.
For more information, contact the Innate Healthcare Institute.