Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. Since you are very fit and have been working out for so many years there should not be a major problem here, it mostly happens because of dehydration, since you work out, major part of cardiac output (blood pumped by heart every minute) is diverted to the parts of the body that are used during workouts (muscles) and if at the same time you are not hydrated well you can feel this way, what I would suggest that keep your self well hydrated during your workouts, specially with adequate electrolytes and these symptoms won’t occur at all, suppose it does even after the workouts than you need to get yourself evaluated, and the best way of doing that is stress test or stress echocardiogram, but that’s not needed as of now, just hydrate yourself well and you should be okay. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr Raza Ali