Hey guys I don't get it either! I just try to keep fit and exercise but if I push myself too far "which I never know what is too much" I get palps that make me feel terrible for a day. It happened again after a four mile ride the other day, so frustrating as I just love exercise but never know when I will get that big beat that makes me feel so weak and exhausted. I try to ignore it but the last time I was so weak after the attack I could not stand up and fell over. It was really embarrassing as some walkers had to pick me up and they wanted to call an ambulance whilst I was panting for breath. I had to tell them I was fine but I am unusual and have these attacks that medical science can not explain. This as usual wasn’t a normal panic attack as it only happens when I exercise, I understand that these reactions are normal for me as much as other people get very worried by my symptoms, I will not let them beat me! In fact I work out even harder to try to induce them to build up my tolerance.