Basically what you really want to do is moderate exercise within the bounds of your abilities. Alas, that won't win you a bike race, will it? Well, not a big one, anyway. Trouble is, the commitment you need to make to competitive sport is OTT. Everything about it is wrong, yet it's addictive and feels so good. Given that you are probably going to do it anyway, you may as well read up on the downsides - the risks. If you want to "succeed" then at least do it fully informed.
Effects of Intermittent Exercise on Cardiac Troponin I and Creatine Kinase-MB
Strenuous physical activity is destructive for cardiac function causing an increased risk of myocardial infarction during and one hour after the exercise bout.1 Cardiac fatigue is exercise-induced cardiac dysfunction in the absence of underlying cardiovascular diseases with a large number of symptoms and an unclear etiology.