For me, it’s both at rest and when I start to use something like my arm. Both forearms and upper arms have pain while at rest and slightly more pain when engaging in an action (reaching, moving a pillow). But then I’m able to continue the task (gardening, emptying dishwasher) without any additional pain. I’m learning to just go ahead past that initial pain and do what I need to for as long as I can. It requires more rest later but at the time, I can do much of the task. Also, every day is different.