I regularly exercise, even when I having a flare-up. I just take my time and go slower. If I don't keep moving I'll be on the couch for days.

Exercise for me, other than a little bit of walking also causes me to flare..

depends on the kind of exercise for me--any exercise with impact sends me into a flare.

What is HIIT? If you don't mind me asking

I spin at the gym 2x/week. 45min each time. I get into a zone and try to block out the pain. Not sure if its helping or worsening. Ive been a spin instrcutor for 12 yrs and its a passion of mine In not giving up. Some days, i feel more mobile and others I can barely make it to my car. I guess time will tel( but im a high energy person who isnt going be satisfird with tai chi or yoga. Used to do cardio kickboxing and hope to get back to that on a modified scale soon. I used to work out 5-6 times a week so to only now do 1-2 is hard mentally but its the best i can do. Ive see. A bunch of articles about HIIT for fibromyalgia but time will tell. Good luck!