The article by Scharhag et al. offers a plethora of information, but I am missing a concrete value for a healthy limit to endurance exercise.
The section on changes to the ECG contains two apparently contradictory statements:
Atrial fibrillation is more common among middle-aged and older endurance athletes than it is among athletically inactive persons of the same age.
On the other hand, it has been found that moderate endurance training, as performed in preventive-fitness programs, may actually lower the risk of atrial fibrillation in old age.
The only explanation for this contradiction is the intensity of the endurance exercise. More intense training is more likely to result in overstretching of the left atrium. Atrial remodeling then enables atrial fibrillation. Medicine can define clear threshold values for blood pressure, pulse rates, and cholesterol concentrations. For me as a general practitioner it would be very important to know a definite threshold value for healthy physical endurance exercise. What can I recommend to my patients as moderate endurance exercise?
Research is currently not able to provide evidence based data to answer this question, which is relevant for routine clinical practice. Many years ago, the campaign “Trimm dich [get fit] Aktion 130” was launched. However, a general pulse rate of 130 for everyone is not differentiated enough and probably not scientifically supported either. I would welcome definitive values, based on age and weight. To this end, age-dependent performance in watts/kg body weight could be used. Even more simply, an endurance exercise threshold could be given as a percentage of the maximum age-related pulse rate. This could form the basis for future studies.
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References
- 1.Scharhag J, Löllgen H, Kindermann W. Competitive sports and the heart: benefit or risk? Dtsch Arztebl Int. 2013;110(1-2):14–24. doi: 10.3238/arztebl.2013.0014. [DOI] [PMC free article] [PubMed] [Google Scholar]