You'd be hard-pressed to find a guy bragging about working on his serratus anterior muscle, any more than you are to find someone who knows what that is to begin with.

Easy to locate but hard to explain, the serratus anterior is a muscle that wraps around your ribs, just under the armpit. If your body fat percentage is low enough, the muscle will give your abdomen a shrink-wrapped look—like there are fingers pointing from your ribs to your six-pack.  

Despite its “anterior” (front of the body) position, the muscle plays a really important part in shoulder stability. “The role of the SA is to help hold the scapulae on the rib cage, helping to control their motion, which is critical for any movements of the shoulders,” explains strength coach Pete McCall, MS, C.S.C.S. “The SA helps control the upward rotation of the scapulae during overhead movements, as well as prevents them from ‘winging’ or popping out during pushups.”

McCall recommends the following three exercises to strengthen yours for greater shoulder stability, and a lower risk for an impingement or rotator cuff tear.

3 exercises to engage your serratus anterior:

1. Scapular pushups

“This is a great exercise to do as part of a warmup for a heavy chest pressing or overhead pressing workout,” McCall says. Come into the top of a pushup position. Press your hands into the ground and round your midback up, pressing the shoulder blades apart. Hold for 10 seconds at the top, then relax, allowing your chest to drop and the blades to come together for two seconds. Press up again. Don’t let your arms bend at all. Do 6 reps, then rest for up to a minute. Do 1 or 2 more sets.

2. Overhead kettlebell carry

Since one of the SA’s roles is stabilizing your shoulder during overhead movements, it makes sense to train it exactly that way. You can do this move with a dumbbell, but the kettlebell, with its off-center weight, creates a greater challenge. Grab a light-to-moderate kettlebell in one hand and press it overhead. You can make it harder by using a bottoms-up position, which will also challenge your grip strength. Walk 8 to 10 yards, then turn around and go back. Switch arms and repeat for 2 to 4 sets. “It's also a great core exercise,” McCall says.

3. Prone I/Y/T/W

This exercise combines the overhead movement with scapular contraction. The aim here is to move slowly—speed through and you miss out on all that great stabilization work. Lie on your stomach on a mat, arms extended overhead by your ears. Squeeze your core and upper back to raise your arms, face, and chest off the floor. Lower down. Widen your arms to form a Y shape with your body, then repeat the squeeze and lift. Lower, then widen your arms again, this time to form a T, and repeat. Finish by bending your elbows in toward your sides to form a W, and raise up one last time. Do 6 reps of the entire sequence. Rest one minute and repeat for 2 or 3 sets.