This is a simple exercise for the back, shoulders and triceps. As with any exercise involving exercise or resistance bands you can adjust the difficulty by using different strength exercise bands.
Stand with feet slightly apart. Arms should be raised to shoulder level, and elbows bent. Hands should be out in front each grasping a portion of the band.
Exhale and pull band straight outwards, forcing hands away from each other. Hold for 2 seconds, exhale and release.
Do 10-12 reps to complete this exercise. For extra challenge, squeeze shoulder blades together at the end of the movement and fully contract the triceps.