The serratus anterior does help with breathing, but it’s not one of your primary breathing muscles. It’s classified as an accessory muscle of respiration, meaning it gets recruited when your body needs more air than the diaphragm and intercostal muscles can deliver on their own. During normal, quiet breathing at rest, the serratus anterior contributes very little. During heavy exercise, respiratory distress, or forced deep breaths, it plays a more active supporting role.
How the Serratus Anterior Assists Breathing
The serratus anterior wraps around the side of your ribcage, attaching to ribs 1 through 9 along their outer surfaces. When it contracts with the shoulder blade held in place, it can pull the lower ribs upward and outward. This assists with a movement called “bucket-handle motion,” where ribs 6 through 10 swing outward like the handle of a bucket lifting away from the sides. That motion widens the chest cavity from side to side, giving your lungs more room to expand.
The upper ribs (1 through 5) move differently. They swing forward and upward in what’s called “pump-handle motion,” increasing the front-to-back depth of your chest. The serratus anterior primarily assists with elevating ribs 6 through 8, so its contribution to breathing is mostly about expanding the lower and lateral portions of your ribcage rather than the upper chest.
When Your Body Actually Uses It for Breathing
During everyday breathing, your diaphragm does the heavy lifting. The serratus anterior stays relatively quiet. A study examining serratus anterior recruitment during graded cycling exercise found that in healthy subjects exercising upright, the muscle showed little effort toward ventilation. This makes sense: your body reserves accessory muscles for situations where the primary muscles aren’t enough.
The serratus anterior becomes more important during forced or labored breathing. If you’re gasping after a sprint, breathing hard during intense exercise, or struggling to breathe due to a lung condition, your body recruits additional muscles to move your ribcage more aggressively. In these situations, the serratus anterior, along with the pectoralis minor and the scalene muscles in the neck, kicks in to help expand the chest beyond what the diaphragm can accomplish alone.
The Scapula Connection
What makes the serratus anterior’s breathing role interesting is that it doubles as the primary stabilizer of your shoulder blade against your ribcage. These two jobs are deeply connected. For the pectoralis minor to help lift ribs 3 through 5 during a deep breath, the shoulder blade needs to be held firmly in place. The serratus anterior provides that anchor. Without it, the pectoralis minor would just pull the shoulder blade forward instead of lifting the ribs.
This dual function means that weakness in the serratus anterior can affect breathing in two ways: directly, by reducing its ability to elevate the lower ribs, and indirectly, by destabilizing the shoulder blade so that other accessory breathing muscles can’t do their jobs effectively.
How Poor Posture Disrupts This System
When the serratus anterior becomes underactive, the shoulder blade tends to “wing” outward, and the upper back rounds forward into excessive kyphosis. This postural pattern, sometimes called upper crossed syndrome, doesn’t just look slouched. It physically restricts how much your chest wall can expand.
Research on this connection shows a two-way relationship. Reduced serratus anterior activation contributes to altered breathing mechanics, pushing people toward shallow, upper-chest breathing. But the reverse is also true: habitual upper-chest breathing patterns can change scapular positioning and further inhibit serratus anterior recruitment. The muscle and the breathing pattern feed into each other, creating a cycle where poor posture and inefficient breathing reinforce one another.
Transitioning from chest-dominant breathing to diaphragmatic breathing can help break this cycle. When you reduce excessive upper chest movement, it corrects scapular positioning, which in turn makes it easier for the serratus anterior to activate properly.
Strengthening the Serratus Anterior for Better Breathing
A randomized controlled trial on men with COPD and rounded-shoulder posture tested an eight-week program that included serratus anterior strengthening alongside pectoral stretching and lower trapezius exercises. The serratus anterior exercise used was a modified push-up performed on a stable table surface, essentially a push-up plus where you push your shoulder blades apart at the top of the movement. Sessions were three days per week for eight weeks.
The logic behind this approach is straightforward. Strengthening the serratus anterior improves scapular stability on the chest wall. Better scapular positioning opens up chest mobility. Greater chest mobility means the lungs have more room to fill. The researchers noted that improvements in chest mobility and breathing coordination appeared to facilitate better neuromuscular activation of the serratus anterior, reinforcing that positive feedback loop.
If you want to try this at home, the table push-up plus is a good starting point. Stand facing a sturdy table, place your hands on the edge, and perform a push-up. At the top of each rep, push a little further so your upper back rounds slightly and your shoulder blades spread apart. That extra push at the end is what targets the serratus anterior specifically.
What Happens When the Serratus Anterior Can’t Work
Clinical evidence from rib fracture patients offers a useful window into the serratus anterior’s role. When doctors perform a nerve block in the tissue plane around the serratus anterior to control rib fracture pain, patients show measurable improvements in breathing function. In one study, patients who received this block had an 11% increase in their expected breathing volumes at three hours, while those who didn’t receive it actually had a 3% decrease. The improvement faded by 24 hours as the block wore off, but the short-term effect was clear.
This tells us something important. Rib fracture pain causes the muscles around the injury to guard and splint, restricting chest expansion. When that pain is removed from the serratus anterior region specifically, patients can take deeper breaths almost immediately. The muscle doesn’t need to be contracting powerfully to matter. It just needs to not be inhibited. Pain, weakness, or poor positioning can all prevent the serratus anterior from allowing full ribcage expansion, even during passive breathing where it’s not actively contracting.