50 years old and very good health normally - exercise 4-5 days per week for about an hour at a time, running 3 miles and calisthenics. Had a physical with EKG done recently, for a military deployment that showed a normal (for me) sinus bradychardia, but now with a 39 degree left axis deviation. I had an EKG done just about 6 month prior for a regualr physical and it showed only the normal sinus bradychardia - nothing about any sort of deviation. I have also been experiencing some short bouts of what seems to be palpitations and shortness of breath - usually when I am not exercising. These bouts seem to be more often when I am laying down to sleep. I ve also experienced some slight numbness in my left arm on occaision and today felt some slight chest pain while exercising this morning. Can this be related to the Left Axis Deviation and how can an EKG go from normal (with sinus Bradychardia) to a 39 degree Left Axis Deviation in such a short time? There was never anything on any previous EKG that said anything about a deviation. I have been getting physicals all of my life - usually with EKGs, as a Military Pilot. Should I be concerned about continuing exercising and should I have futher tests done? Thank you.