Check out these two isometric exercises focused on wrist pronation and supination!
Isometrics are an excellent way to re-introduce exercise because they produce what is called an analgesic effect - that can reduce the pain you feel by altering the nociceptive/pain pathways to your brain. There is literature to support isometrics for managing conditions such as lateral elbow tendinopathy, patellar tendinopathy, and achilles tendinopathy.
Wrist isometrics in the sagittal plane have gained popularity, however wrist isometrics in other planes should be incorporated as well. I love this pronation/supination isometric exercise because it also promotes proximal stability as well.
Without the set-up to promote resisted pronation/supination, this exercise is no different than shoulder external/internal rotation isometric walk outs. According to an article by Coombes et al. 2015, other interventions supported for treating lateral elbow tendinopathy included rotator cuff strengthening, thus it is a win win!