Stand holding onto the resistance band. Lift your arm out to 90 degrees abduction and external rotation. Brace yourself in this position as you prepare to lunge forwards and then in multiple directions. As the band tightens try to stop the shoulder from moving from its starting position. Be particularly aware of any hitching at the shoulder, forward moving or pressure in the front of the shoulder or the elbow beginning to drop down.
If the exercise becomes too easy or is too challenging for you, your physiotherapist will be able to adjust the resistance band to suit your needs.