If you sit is a traditional crossed-legged position the movements involved in those position include:
1. Hip flexion
2. Abduction of the femurs
3. One can add rotation in that position to stretch the rotators of the spine as well as the obliques.
4. By placing the hands on the floor and elevating the sternum one can extend the spine.
I hope this is of help to you.
The answers given are all excellent. One exercise I didn’t see mentioned is the standing squat using either a barbell of dumbells. In the recovery phase of the exercise hip flexion and slight abduction, knee flexion and ankle dorsiflexion are the joint movements involved. In the effort phase hip extension and slight adduction, knee extension and ankle plantar flexion are the movements involved.
If using dumbells, your client can add shoulder flexion (sagittal plane) or abduction (frontal plane) to 90 degrees in the recovery phase of the squat with shoulder extension or adduction during the effort phase of the squat.