Is too much exercise bad for the heart? | health

The health benefits of exercise are well established and extend beyond the cardiovascular system. These benefits stem from the modulation of traditional risk factors for atherosclerotic cardiovascular disease, as well as an anti-inflammatory effect on vascular endothelium and changes in autonomic regulation. A study of nearly 900,000 individuals showed that the physically active group had a reduced risk of cardiovascular death and all-cause mortality. These data suggest that a greater volume of exercise results in greater cardiovascular benefit. But is there a limit?

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Heart Exercises I Athlete — Photo: Istock Getty Images

A more cautious approach is needed in individuals with established heart disease, where the volume and intensity of exercise may need to be moderate, for example. Furthermore, Endurance athletes routinely exercise far beyond World Health Organization (WHO) recommendations. The elevation of loads and exercise volume promotes a series of electrical, structural and functional adaptations, collectively called “athlete’s heart”. The nature and magnitude of changes vary by sport discipline, ethnicity, age, and sex, and may overlap with mild phenotypes of conditions associated with arrhythmias and sudden cardiac death.

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Extreme cavity dilatation, left ventricular hypertrophy, elevation of arterial calcium scores, release of acute cardiac biomarkers, myocardial fibrosis, and cardiac arrhythmias have all been reported, raising concern of an inverse relationship between exercise volume and cardiovascular health, with decreased exercise volume. cardiovascular benefit and potential harm. Therefore, there is an ongoing debate as to whether there is a threshold that constitutes ‘excessive exercise’, which can induce harm.

Atrial fibrillation (AF) is the most common sustained arrhythmia in the general population, is a leading cause of ischemic stroke, heart failure and impaired cognition and quality of life, and increases the risk of death. The incidence of atrial fibrillation increases with age. It is well established that exercise reduces or mitigates these risk factors, and as such, regular exercise can prevent the onset of atrial fibrillation, as well as improve symptoms, morbidity, and mortality in those with established atrial fibrillation.

In a study of 6,000 veterans with a mean age of 56.8 years who underwent an exercise tolerance test, the fittest individuals had the lowest risk of developing atrial fibrillation, with a 21% decrease for each increase in MET (a measure that assesses metabolic parameters) on exercise capacity. Importantly, however, the risk reduction decreased in those performing high-intensity exercise (>6 METs).

Since then, evidence has emerged that shows a link between long-term intense resistance exercise and atrial fibrillation in an “exercise paradox”. Larger epidemiological studies and several meta-analyses have shown that the incidence of atrial fibrillation is two to five times higher in endurance athletes than in non-athletes.. There is evidence to support the notion that exercise intensity, duration, and type of sport affect the onset of arrhythmia.

In a study of 52,755 cross-country skiers participating in a 90 km cross-country ski race, participants who completed more than five runs were at increased risk of atrial fibrillation. Similar findings were seen among healthy middle-aged men, with those who participate in high-intensity running having a 53% higher risk of atrial fibrillation compared with men who do not exercise. This would suggest that the association between exercise and atrial fibrillation is not restricted to elite athletes, but is also observed in the general population.

The mechanism of atrial fibrillation in athletes is not well understood, with much of our knowledge based on animal models. Vagal tone, which is chronically elevated in athletes, is believed to be one of the most important contributors to the development of atrial fibrillation. In addition, atrial remodeling, in the form of atrial dilation and fibrosis, is increasingly being recognized as a factor. Episodes of atrial fibrillation are more common during states of increased parasympathetic tone (rest, sleep), but sympathetic stimulation during exercise can also trigger atrial fibrillation, in association with atrial wall stretching and inflammatory cytokines.

Most studies investigating the relationship between atrial fibrillation and exercise have focused on elite male athletes, who have historically dominated the elite sports scene. The link between exercise and atrial fibrillation in female athletes is less clear. In an analysis of more than 140,000 male and 160,000 female athletes, increasing levels of physical activity were associated with atrial fibrillation in male but not female participants. Exercise, but conversely, intense exercise was protective in women. Likewise, a more recent meta-analysis also concluded that the overall risk of atrial fibrillation is lower in female athletes than in male athletes. However, there is still a lack of data that would prove such a situation in the study when comparing exercise levels among females.

In conclusion, the exact dose of exercise that confers risk of atrial fibrillation remains uncertain, lacking high-quality prospective studies with well-defined study populations. A figure of about 1500 to 2000 hours of exercise over a lifetime has been suggested as the threshold at which the risk of atrial fibrillation increases, with a peak age of onset above 40 years. Atrial fibrillation in younger athletes is uncommon and should prompt evaluation for underlying heart disease.

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* The information and opinions expressed in this text are the sole responsibility of the author, not necessarily corresponding to the point of view of ge / Eu Atleta.

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