The glucosamine could definitely help.

Do you stretch at all? Get adequate protien?

I get all sorts of aches and pains if I don't stretch daily or take in enough protien to recover right.

Making sure you have good form is probably pretty important as well, whether fly fishing or not. If your slouching around all the time that could definitely lead to some problems when combined with fishing.

I'm not sure about the glucosamine and chrondoitin. They're supposed to help a specific condition - osteoarthritis- and if your pain is due to other problems, supplements may not help. Some other ideas in case your problem isn't caused by joint cartilage deterioration:

You don't say what else you do that requires physical exertion. Do you lift weights to strengthen your deltoids, trapezoids, and upper arms to build up the muscles around the rotator cuff? That'd help protect the joint/tendons/ligaments and might reduce the side effects of overuse without adequate strengthening.

Strengthening your core may also help. If you focus on using your entire body to cast and pull fish in, instead of just your shoulders/arms, you'll put less wear and tear on the smaller muscles and joints.

I used to have some minor shoulder issues as well, I did some research and came across this video: http://www.youtube.com/watch?v=A0ONHZmsFec&feature=player_embedded

I have been doing these exercises on and off for many months and everything is fine now, I have a very physically demanding job and am sure I had some rotator cuff issues for a while which I did not want to get any worse.

I have taken glucosamine sulfate for nearly 20 years after college football and 4 knee surgeries. I recommend giving it a shot if you think you have osteoarhritis even though it is not paleo. Find what works regardless of the dogma. It will take over a month to have an effect in my experience so I suggest rolling with it for awhile. Also something that took me a long time to learn is if an activity or movement hurts your body stop doing it. Find something close to what you were doing that doesn’t hurt. My .02 good luck!

The repetitive actions involved in casting during fly fishing can create trigger points in the muscles of your shoulder girdle, particularly infrapsinatus, supraspinatus, deltoid, and the middle fibers of the trapezius, that can create the feeling of joint pain right in the shoulder itself. The "on and off" nature of the injury makes it sound like it is not acute (strain, partial thickness tear, etc...), but it should be looked at.

If you are interested in going a natural route, a chiropractor can easily manage your shoulder. They are well trained in dealing with these trigger points, as well as any other possible pathology you might have there, whether sprain, strain, tear, etc... They can figure out what it is and get you healing and back to fishing without any intrusive surgery or medication. Good luck!

Shoulder injuries are among the most common injuries and can create significant pain.Shoulder joint pain is any pain in or around the shoulder joint. Glucosamine and chondroitin are two molecules that make up the type of cartilage found within joints. Inside your joints, cartilage undergoes a constant process of breakdown and repair. However, to be properly repaired, the building blocks of cartilage must be present and available. The theory behind using the glucosamine and chondroitin joint supplements is that more of the cartilage building blocks will be available for cartilage repair.

Certainly not the scientific study you'd prefer, i dont know much abt it ...but my friend has been taking Glucosamine and Chondroitin for years. Joint pain that was chronic and annoying is now 100% gone, but in hia shoulders and elbows the improvement is obvious and complete.... he also reporting miraculous results on muscle and tendon problems. Do keep exercising the shoulder carefully, have a therapist teach you the best ways to do this.