Hello and thank you for using HCM. I carefully read your question and I understand your concern. I will try to explain you something and give you some advises. As you describe my opinion is that we are dealing with a rhythm issue. Someone might feel heart palpitations for different reasons. It may be a simple sinus tachycardia that means that the heart is beating regularly over 100 beats for minute. Its normal resting rate is between 60-100 beat for minute. You may experience palpitations because of extra-sistolyc beats. This are electrical impulses generating from parts of the heart different from normal sinus rhythm. This gives the sensation of an escaped, skipping beat. But there are all sow different rhythm problems like atrial fibrillation ore supra ventricular tachycardia where the heart doesn t beat normaly, it suddenly beats fast or in a chaotic way with very high frequencies and this might be what we call atrial fibrilation. My opinion is that lifting weight is not the reason of your palpitations. Its quite known in cardiology that during physical exertion the heart rate raises. Its maximal frequency should go 220 minus your age and it should slowly go down. But you describe a long history of palpitations and a suddenly heart jumping just for some seconds, immediately dropping down. So, I think that we should see what are this rhythm fluctuations. Does this happens even in a a resting situation or only when you exercise? If i was your treating doctor I will recommend a blood analyze, your thyroid hormones, an electrocardiography, echo-cardiogram and of course a holter monitoring to see your rhythm tendency. Ones we have all these we can say what are these palpitations and how to treat them. This are all for a simple chek-up to reduce this episodes in the future. Whish I was helpfull. Take good care. Best regards