What might be going on with an experienced runner who develops a slight pulse irregularity after running for two hours. Individual is senior male, good health, last stress test normal, no shortness of breath or notable tiredness, one hour runs seem effortless with no after effects. Is this a sign of "over training" or over exertion? Thanks.
Perhaps but the better question is "why take a chance?" Have a cardiologist (preferentially) take a look at you.
Can we have electrically related, cardiological events, "misfires" if you would, that are caused by over <fillin>. Sure.
What do you consider a "slight pulse irregularity".