Hi, I had a very similar problem to many of you on this thread, and thought it might be useful to some of you to relate my own experience.

I lost all strength in my left tricep after no apparent trauma or other injury (detected by being unable to even hold up my body on triceps dips), and felt instinctively that it was due to the fact that like many others on this thread, I always slept on my side, and regularly switched sides during sleep.

Over a period of several days, the condition worsened and I developed numbness in the fingers of my left hand. Even a single press-up was impossible, so it was fairly obvious that as my pain wasn’t very intense, it must be a nerve problem.

I went to see my Physician who sent me for an MRI, which revealed that I had a herniated disc in my neck, which he diagnosed as the likely cause. But having done my own Google research, my symptoms and results of the tests shown on YouTube had indicated that a nerve pinch in the Upper Thoracic Outlet was more likely the cause.

I decided to see an Osteopath, who didn’t even look at my MRI scan photos, but instead proceeded to do some of the tests I’d tried myself from YouTube, plus some others. He told me that in his view, though he didn’t doubt that I had a herniated disc, the most likely cause of my nerve pinching was pinching in the Upper Thoracic outlet. He gave me two sessions of intensive massage around the pec and trap surrounding the Thoracic outlet and things immediately began to improve.

He told me that many people actually go through their whole lives with a herniated disc and never experience any symptoms, so it can be a bit of a red herring in diagnosis.

Returning to likely causes, I think that bodybuilders in particularly are vulnerable to this injury if they sleep on their side, because their shoulders are very broad. Unless they have a large stack of firm pillows, there is a tendency for the upper-side shoulder to collapse forward during sleep to compensate for the large gap between the head and under-side shoulder that would otherwise cause discomfort. So for prevention, I think learning to sleep on your back is a good strategy.

So much for the cause and diagnosis. Nine months after my initial injury I still have significant atrophy of the left tricep. I have found that the best means to encourage improvement has been to do hammer triceps extensions, because through trial and error, this is the exercise that showed the greatest disparity between the injured and uninjured triceps in terms of strength. I have seen a definite, though slow, improvement in strength, but the atrophy is still there. I’m assuming that this is just going to be a very slow process of re-activating neural pathways somehow, so will need to be patient.

I have found that flat bench pressing seems to aggravate the injury and have stopped doing it altogether now, but strangely inclined bench press seems to be ok (certainly nowhere near as bad at least). Not doing bench pressing is hugely frustrating, as I lost at least 10 pounds of upper body muscle mass, I’m sure due to the lack of heavy bench pressing. But I just have to take the long view and let nature do its thing. Good luck to all of you suffering the same symptoms, I hope my experience in some small way is of use to you.

Incidentally, a side note about Physicians and diagnosis in all this. I’m not a Physician, and I know that self-diagnosis via Google must always be done with extreme care and perspective. That said, I have much more time to research my condition than the few minutes my Physician can afford me, and my motivation for correct diagnosis is far higher, regardless of how professional he/she is. I’m an Engineer by profession, and I would never presume to know everything about my own narrow field of the subject. A Physician can’t be expected to know everything about a far more complex system than any I will ever work on. The difference between our professions is that by the human nature of his work, his clients expect a definitive diagnosis, whereas mine understand that I can’t always provide it. I say all this because whilst you may be fortunate to find a Physician who fully understands and is able to accurately diagnose your condition, this is in practice often quite a tall order, so doing a bit of your own research, like reading this thread, even if it only leads you to seek advice from another professional, is time well spent in my opinion.