Background Numerous prospective cohort studies in the last decades established that regular endurance exercise (EE) has benefits for the heart reducing cardiac morbidity and mortality. In contrast, some papers published recently pretend that too much of EE may have adverse cardiac effects and do harm the heart. This systematic review analyses right heart (RH) examinations, cardiac markers,cardiac imaging studies, and longevity in athletes with longstanding EE.
The results Show some inconsistencies of the two opposing statements.Old and current RH studies with even catheter during stress testing did not show any RH injury even at exhaustion in athletes, this was recently confirmed by a study from Dallas and from NMR studies in Germany. Cardiac markers (esp. Troponin) have been reported in many studies to be elevated after long and vigorous physical activity (eg marathon) with less increase in the better trained athletes. Control measurements 24 to 48 hours after end of race showed that markers mostly returned to normal, prospective analyses did not reveal any damage to the heart (RH and left heart). Imaging by echocardiography performed by many authors of many athletes have not shown any cardiac dysfunction after longstanding EE. Only one centre reported RH dysfunction in cyclist with EE, this was not confirmed by the Bern group in marathoners. MRI studies in marathoners have been performed with cross section studies in three centres, in two with selection of volunteers after announcment in regional journals. In small numbers late gadolinum enhancement has been observed, in one centre with 50% of former smokers, some more may have had cardiac signs and symptoms. So there is a selection bias towards athletes with occult diseases. Random examinations of marathoners were unable to confirm these findings. Finally, the lifespan of athletes and EE have been evaluated in a large number of studies. The vast majority reported longevity with increased lifespan between 2 and 5 years. The only possible hazard is the increased number of atrial fibrillation (Afib) in vigorous EE, whereas moderate EE may be protectve against AFib.
In conclusion The current studies presenting data that EE might be hazardous, have methodological inconsistencies, selection bias, are cross sectional only with partly small numbers of athletes. So far, many benefits of EE do by far outweight a possible hazard. Beforeall,preparticipation examination is one of the best measure to prevent hazards during or after EE over many years.