Question
I am 39 years old, I train with weights regularly 3 times a week, I trained since I was very young and never had any significant injury nor any muscle problem at all. I do not use heavy weights and when I train shoulders I use to warm up with dumbbell front raises, then I do standing military presses with 90 lb aprox. Never had pains not during the exercise nor after them. But yesterday, watching TV I started feeling a sudden and strange pain in my front left deltoid. It does not feel if my arm is relaxed and hanging, but when I raise it and the arm goes over the level of my shoulders(horizontal position), both extended or bent, as if I were doing dumbell presses I start feeling the pain (I assume that is when the muscle works to keep the arm raised).
In a relaxed position, I touch my front shoulder where I feel the pain and applying certain pressure to it I start feeling the pain as well, it seem to be a tendon I think. The exact place where the pain feels is the joint between the front deltoid and the chest muscle, but clearly in the front deltoid. Never experienced this kind of pain in more than 20 years of training. Yesterday I had to train chest (I do only arm push ups and dumbbell pullovers) but couldn't do anything.
Thanks in advance and would love to know any approach about this strange shoulder pain. Thanks!!

Answer
Fabricio,

You have a common condition.   In general it is called a "shoulder impingement syndrome."   Likely you do have a tendon that is a problem, and most likely it is the "subscapularis" at its insertion based on where you are indicating the pain to be.    You need to have someone test the subscapularis isometrically, and/or do the "subscapularis lift-off test."    The second tendon that is very often a problem and can refer pain into the region where you are indicating, is the supraspinatus, the uppermost rotator cuff muscle.  The tendon of the supraspinatus can easily get impinged when you raise your arm overhead.    There is a lot of literature on these conditions and how to go about treating it.   Feel free to ask me more questions after you do some research on this.    

Dr. G'