OMG, yes! I tried free-motion quilting for the first time a couple of weeks ago on my DSM - for about 2 hours with no breaks - and my rotator cuff took about two weeks to heal. Guess you and I both need the advice above. (Thank you, more experienced quilters!)

Ergonomics and take regular breaks. Set table so your elbows bend at 90 degrees. Make sure your shoulders are in a relaxed position before you start. Don't sew more than 45 minutes at a time. Those are the basics. My biggest issue is getting tense from pushing the fabric around. I found it much better to quilt only a small section at a time. It keeps my shoulders from tensing up.


Pam

I never had a problem but it is like everything else in life, you should get up and move about and stretch every 15 minutes. Check some of the above posts and see if you are set up correctly.

Yes I have had rotator cuff surgery on both of my shoulders I do believe it was from wrestling the quilts Now I have a long arm and it does not bother the shoulders

I also have an old rotator cuff injury and have to be careful. Sit up higher so that your forearms sit flat on your sewing table without your shoulders scrunching. It seems wierd at first, but helps so much. Keep your elbows in as much as possible. When you stick your left elbow out it aggravates your shoulder. Also try hard to not clench your jaw and neck. I tense up too much and have to be very conscious.

Are you sure it's your rotator cuff? I was having problems with my shoulders and the doctor diagnosed calcific tendinitis.

"Calcific tendinitis (also called calcific tendinopathy) happens when calcium builds up in the tendons. It is most common in the shoulders. People most affected by calcific tendinitis are between 30 and 50 years old, and women are more likely to have it than men. It isn't normally a sports-related problem."

It was easily treated - I had an in-office procedure to loosen and remove most of the calcium deposit, followed up with physical therapy, and am right as rain now.

I purchased a wooden quilting frame which was set up for my machine and me. Back home just a case of putting it together. I was so excited and pumped up I did over two hours of nonstop quilting( only to fill bobbins). The next day I was over the moon with my success. The day after that I could handle move from my waist upwards. My arms, shoulders back etc all hurt. Movement was very difficult. I had done too much in one go.
Since then I have a 20 minute rule for any sewing. 20 mins sew 20 mins relax and catch up with jobs or have a drink. I have had no more problems.

Peckish, yes it is rotator cuff. I've damaged both of them through separate horseback riding accidents so I know what it feels like.
Thanks to everyone for the suggestions on how to sit differently to guard against further damage. I was sad when I began thinking I couldn't free motion anymore!
Watson

I would also suggest to warm up your muscles! It sounds silly, but do shoulder rotations forward and back and arm circles. I have a shoulder injury from many years ago, and doing push-ups without being properly warmed up caused it to flare up again. Had I warmed my muscles up correctly, I am sure I could have avoided all that pain.

I've had rotator cuff problems from computer mouse use. What causes mine to flare up is if I don't keep my elbow on the desk as I use the mouse. I don't know if that's what causes yours to flare, but it might help to make sure your arm is supported and not putting any stress on the shoulder area. That and not tensing my shoulder help a lot. I rarely have any problems now.