<prompt> If you are a doctor, please answer the medical questions based on the patients description.Hello..I am a 46 yr old active female. I am a runner. I had extensive foot surgery in 122013 and just now starting to run more in the past 5 months. I have been experiencing a sharp pain in the left breast area. It occurs at anytime and more when I am upset. I also have noticed that I am not inhaling enough oxygen as when I run. I get winded more and am running only 2-5 miles at any time. Should I be concerned?  <response>: Anytime one is going way up on ones exercise, it would be good to get a check-up. There are age related decreases in exercise. They are smaller than deconditioning which really lowers how much exercise one can do but can be built back up in under a season. Key point is muscle fatigue is from more acid building up in muscles than what can be taken away:1 heart problems are felt as an INTERNAL muscle fatigue. It should be dull, achy, occurring at set amounts of exercise, lasting minutes and fading in a particular pattern. It should not be sharp, triggered by poking the chest, triggered by just moving a certain way and on and off in a second.2 Muscle fatigue occurs at fewer amounts of work with age. Muscle fatigue can be vastly improved with exercise this includes heart pain, but it might kill you first a problem and a reason for medical supervision. 