Arm feels weak reaching behind back
You reach back for a seat belt, a back pocket, or a bra clasp. The arm gets partway there and just gives out. The strength is not where you expect it to be.
Reaching behind your back rolls the arm bone inward. That move asks a lot of the rotator cuff. These four small muscles hold your arm bone in its socket.
When one of those tendons is frayed, torn, or swollen, the arm can go weak at that one angle. Years of wear are a common cause. A fall, a hard yank, or heavy lifting can start it too.
Some people feel sharp pain with the weakness. Others feel almost none, and only notice that the arm will not go where it used to. Weakness on its own still counts as a sign worth looking at.
When to see someone
See a doctor if the weakness started right after a fall or a hard yank. Go now if you cannot lift the arm at all, or the hand feels numb, cold, or pale. Book a visit for weakness that lasts more than two weeks, or for fever with a hot, puffy shoulder.
Below is a list of traditional and home remedies people have used for rotator cuff trouble. Each one carries a grade that shows how much research has looked at it, not a promise of what it will do for you. Read it as a starting point for a talk with your doctor or physio.



