Stand upright facing away from the machine with your feet shoulder-width apart and gripping the handle with an inwards facing palm in front of your hip at shoulder-width while your other hand is rested behind your back.
Exhale and raise your arm out to the side while keeping it straight.
Continue raising your arm until it is parallel with the ground.
Inhale and allow your arm to lower, returning it to the starting position.
After all reps are completed, switch sides and repeat the movement. 10 reps prescribed means you should perform 10 reps on each side (20 total).