<s>[INST] i have had problems with my heart skipping a beat every now and then for about 4 months or so. I have had a few ECG s and an ultra sound and not much come up. I have now had a 48 hour ECG but I am waiting for the results to come back.I am 26 years old 6 foot 2 inches tall and weigh about 189 pounds. I do regular exercise (running about 15 miles a week). I noticed my heart was skipping a beat quite regularly 2 weeks ago so I decided to not do any exercise last week to see if it stopped and it did! I really don t want to stop exercising, my aim is to run a marathon. Is my heart skipping a beat potentially dangerous, should I stop running? [/INST] Hi,Skipped heart beat could be simply VPC's (extra contraction from a normal heart) which can occur with exercise or it could be some other arrhythmia.Let the holter report come & further course of action will depend on its report. Holter is done when you are not exercising.I will also recommend you to undergo a TMT that will report these skipped heart beats during exercise.You can follow up with me after the report.ThanksTake care </s>