Here are some core exercises you can do while still recovering from frozen shoulder:
- Abdominal drawing-in maneuver
- Lying down with knees straight or bent
- Pull the navel toward the bed or toward your spine while breathing slightly
- Do not move the pelvis and chest while doing this
- This exercise is used to strengthen the core muscles which stabilize the spine when you are doing high-impact or repetitive activities such as walking for a long distance
- Lie on you back and bend the knee to 90 degrees
- Slowly lift the head and shoulder off the ground
- You'll feel the abs working as well
For the meantime, try to incorporate the drawing in maneuver especially when you are walking for a prolonged period, or when you are doing your exercises like pilates and water aerobics.
Here is a video of Rick on core exercises as well: https://www.youtube.com/watch?v=dhJecAPD3_k
Also, watch these.