
stand with arm elevated 45 degrees, apply overpressure to rotate forearm into supination, stretching forearm flexors.
Stand, elevate the arm forward by 45 degrees, keeping elbow straight and palm facing forward. Place another hand on the forearm, rotate the forearm in the direction of thumb. Feel for the stretch in the inner side of forearm. Release the stretch and repeat.
Nothing here is a prescription. Your physiotherapist decides which of these are yours, and when.