Question
I am an avid runner and boxer. I run 3-7 miles a day, and go to the gym and punch for about an hour a day. About 4 months ago I switched from regular coffee with about 100 mgs of caffeine to starbucks, which they say has about 300-400 mgs. Since that time I have developed tendonitis in both the knee and achillies. In addition I am having joint cracking throughout my body. I have switched back to the not as strong coffee, but have not gotten better. Could the high intake of caffeine be creating a defeciency of some kind, or an auto immune disease?

Answer
As a former avid runner myself, I know how important your training is and how annoying it can be to interrupt it.  However, also from past experience, I would see a doc soon to explore these symptoms, especially a doc who is sport/running savvy and understands your level of exercise. S/he can put your concerns to rest and advise you on the best way to proceed.