It sounds like you are describing PVCs (or premature ventricular beats). Basically, every once in a while, you have an extra heart beat, which comes before the next scheduled beat (hence the term "premature"). This beat and/or the following beat is felt as a stronger "thud" in the chest. These are very common and harmless in an otherwise healthy heart. It's not unexpected that it didn't show up on an ECG since they are occasional by nature. It is very common to feel them more when your heart rate is slower (like yours, in the 60s-70s) because there is more time in between normal beats, and therefore more time for a premature beat to occur. Caffeine can also increase the frequency of these beats.
All in all, it is safe to continue to exercise. If they are really bothering you and you want to confirm the diagnosis, your doctor can set you up with a Holter monitor to catch the episodes.
Thanks doc.
My doctor has also asked me to set up an holter analogy soon. I might get the leads on by today. My cholesterol, reports have come...they are totally within the range and totally fine as per the doctor's note. but the thuds are bothering me a lot. let me do the holter monitoring. hope it might help.
will get back to you with the results.
Regards
Hey doc..just an inquiry.,...Do my symptoms do for ATRIAL FIBRILATION??
I am dead worried actually.
please do reply