Lateral Deltoid

The lateral deltoid is the head that determines shoulder width. When you see someone with capped, round shoulders, the main contributor is a well-developed lateral delt. Unlike the anterior deltoid, which works in nearly every pressing movement, the lateral head needs direct work to grow. It doesn't get enough stimulus from compound movements alone.

The key exercise for the lateral deltoid is the lateral raise, in all its variations: with dumbbells, on cables, on machines. Cable lateral raises have the advantage of maintaining constant tension throughout the ROM, while with dumbbells the tension is minimal at the bottom of the movement. Wide-grip upright rows are a good complement because they let you use heavier loads. Overhead presses also involve the lateral deltoid, but as a synergist, not as a primary mover.

A frequent mistake on lateral raises is using too much momentum and lifting too high. The lateral delt works mainly in the first 90 degrees of abduction. Past that angle, the lateral delt stays active, but the trapezius and serratus anterior step in significantly to rotate the scapula and allow full abduction. Use a weight that lets you control the movement, focus on the 30 to 90 degree range, and slow down the eccentric. The lateral deltoid responds very well to high volumes and high frequencies: don't be afraid to train it 2-3 times a week.