OK, so there is a mass of information out there on the subject of Afib and sport, but I am a newbie and I'd like to hear from people who cycle and run who have paroxysmal atrial fibrillation. Yesterday I went out on my bike for 1 hr and had no problem keeping my heart rate at around 120 bpm. Today I tried cycling for a couple of hours and in the first 50 minutes kept my heart rate below 130bpm. Then whilst cruising along a flat easy road my heart rate jumped to 200+ bpm and I then stayed in Afib for the next 4 hrs (resting pulse was 130+ whilst sitting watching TV). While I was looking on the internet for advice (i.e. did I need to go to my GP/A&E) I found the site and as I write this my pulse is 54 ppm (normal for me). Help!!!