Pull-ups help increase your upper body strength and work upper body muscles such as your upper back and biceps. But pull-ups don't work your serratus anterior. To target your serratus anterior, you need to do exercises that upwardly rotate your scapula or protract or move it away from your spine in a forward motion. This includes exercises such as the pushup plus and the shoulder press.
Knowing Your Serratus Anterior
Your serratus anterior is located beneath your armpit, originating on the front of your first eight or nine ribs and extending around your back to insert into your scapula. The serratus anterior stabilizes your scapula by holding it against your thoracic cavity or chest wall. It looks like the serrated edge of a knife and is known as the boxer's muscle because when you throw a punch, you protract your scapula and engage your serratus anterior.
Breaking Down the Pull-up
Some trainers believe that pull-ups engage your serratus anterior. This may be because of the action of pull-ups on the scapula. However, ExRx.net notes that your scapula rotates downward when you perform pull-ups. This engages some of your upper back muscles such as your rhomboids and latissimus dorsi, together with the levator scapulae that runs down the sides and rear of your neck. It also has a secondary effect on your chest.
Activating Your Serratus Anterior
Pushups target your chest, anterior deltoids and triceps, but can be adapted to work your serratus anterior. This exercise is called the pushup plus. Perform a normal pushup and at the top of the movement with your weight balanced on straight arms and your toes, continue to push and raise your trunk by protracting your scapula. You should feel your serratus anterior tense. A study reported in the November 1999 issue of the "American Journal of Sports Medicine" found that the pushup plus significantly activates the muscle fibers of the serratus anterior.
Weights and Your Serratus Anterior
Overhead pushing exercises for your shoulders involve upward rotation of your scapula and, according to ExRx.net, target the lower fibers of your serratus anterior. This includes exercises such as the seated shoulder press, military press, and dumbbell press. Other free weight exercises that work your serratus anterior include dumbbell incline shoulder raises and barbell incline shoulder raises. With an inclined bench set at 30 degrees, lie back and hold a pair of dumbbells or a barbell overhead with your arms extended. Hit your serratus anterior by protracting your scapula and rolling your shoulders upward.