Hi all, I never heard of certification or courses on it, but there should be. I am challenged with Fibro and CFS and make up about 70 % of my clients, due to my personal understanding it.
Some days they can take deeper, others lighter. A few things I have noticed in general is:
that heat generally helps them
lighter, slower more rhythmic kneading on an area for a longer time. This may cause you to have to schedule longer sessions. For example, a few passes on their shoulders (a fibro point) won't do, they need you to spend some time there, but usually slow and lighter.
Going deep may feel good to them in the moment, but the next day(s) they usually suffer for it.
Do not work attachments, it's much too painful for them.
The Barnes method of MFR (the gentle , slow stretching, kind) I know there has been some confusion on what MFR is, deep tissue or this gentle unwinding of facial tissue. The latter is the one to use here. MFR really, really helps Fibro people. It can be the most important part of the massage actually for longer term relief.
Know that their body will be different from day to day, week to week. Find out the common Fibromyalgia "hot spots" in the body to work longer, lighter. Neck, base of skull, traps, rhomboids, knees, etc.