Is athletes heart causing my palpitations during exercise? resting hr 50 ,clear echo and 24hr holter. i do lots of endurance training.

Yes: if echo and holter are normal,continue your regular f-up with your physician

Pvcs, : Endurance runners can have skipped beats and irregular heart beat such as atrial Fibrilation during or at the end of an exercise bout . They do not usually have any clinical significance except if the runner has a lot of symptoms or interfere with overall performance.