The iso-lateral raise is a variation on the traditional lateral raise which is great for developing the shoulders.
Primary- deltoids (frontal and medial heads)
Secondary- trapezius, rotator cuff
Equipment– dumbbells. Try a lighter pair the first time as this is deceptively hard.
Start- As you would with a normal lateral raise, you want to start standing upright. Keep the arms extended but slightly bent at the elbow. Laterally raise both arms to shoulder level and hold. This is the starting position.
Movement- From the starting position, keep the left arm in he air and lower the right arm down to the side. Raise back up to the starting position and repeat until you have completed the desired number of repetitions. Follow that by immediately holding the right arm in the air while performing repetitions with the left arm.