Hi, Im 23 and for the second time i have had chest pains while running, Im not a star runner but yesterday i completed 12 km, probably the most i have ever done, I have a fit physique and exercise regularily. the two pains occured months apart... should i be concerned? I had a test done at the hospital and they found no symptoms of a murmor or any other negative sign, could this be just a strained muscle? also i did not feel it this time during exercise it was several hours later after i had gone to bed. center of chest.