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How to Shape the Side of Pec Muscles

author image Martin Booe
Martin Booe writes about health, wellness and the blues. His byline has appeared in the Washington Post, the Los Angeles Times and Bon Appetit. He lives in Los Angeles.
How to Shape the Side of Pec Muscles
Acquiring well-sculpted pecs can be as much of an art as a science. Photo Credit Staras/iStock/Getty Images

It's one thing to say you're going to build up your chest muscles, but if your intention is to develop a well-sculpted -- dare we say, artistic -- chest, there's more involved than just maxing out your pecs with bench pressing. While the pectoralis major, the most visible of chest muscles, is one large muscle, it does have discernible regions. They are more identifiable in terms of upper and lower rather than inside and outside, but for some people, the sides may be the hardest to tone up.

Read More: Upper Pecs vs. Lower Pecs

Mix It Up

There are many chest exercises and while you don't have to do all of them all of the time, it's important to mix them up. It's not just about getting bigger chest muscles. To obtain well-sculpted pecs, you'll want to incorporate exercises that work the muscles from different angles.

The standard barbell bench press is a great place to start for an overall chest workout, but for eliciting activation in all regions of the pecs, it's a good idea to get friendly with dumbbells. Here are a few suggestions to cover the bases. You can get more ideas insights from the American Council on Exercise's study of the Best Chest Exercises.

Dumbbell Flyes

Dumbbell flyes are one of the best exercises for adding muscle fiber to your outer pecs. Proper form is essential to avoid transferring the load to your shoulders, which diminishes activation to your pecs and can lead to injury.

How to: Lying back on a flat bench, hold dumbbells in each hand over the center of your chest, keeping a slight bent in your elbows. Your palms are facing each other. Lower the dumbbells as far as you can. As you lift them back toward the starting position, pause at about three-quarters of the way up. Do eight to 12 repetitions with enough weight to cause muscle fatigue by the end of the set. Dumbbell flyes can also be done on both incline and decline bench.

Seated Chest Press

The seated chest press machine is more or less the vertical version of dumbbell flyes but the change in orientation and the push-resist movement will activate emphasize different muscle fibers. To boost intensity, do them one arm at a time or sit forward away from the backrest so that more core effort to maintain stability. The seated press machine mainly works the outer pecs and is great for beginners.


Ordinary push-ups can be easily adapted to work the outer pecs. The first variation is to use a wider grip than the usual shoulder-width distance between hands. Experiment with different amounts of space between your hands and stay tuned into your outer pecs to see what makes you feel them. Doing push-ups at an incline with your hands resting on a surface that's higher than your feet will also enhance activation of the outer pecs.

Another key push-up variation that will assist in tapering the outer pecs is the push-up plus, sometimes referred to as serratus anterior (SA) push-ups. These are excellent for toning up the aforementioned SA, the two muscles that flank the sides of the torso, adding broadness to the chest.

Burn Fat

Everybody's different, and a lot of people tend to accumulate fat at the outer region of their pecs. So the first order of business is to rid yourself of excess body fat. That almost certainly means losing weight. Unfortunately, there's no such thing as "spot reduction" -- your body mass index doesn't really care where you want to lose it. But as your body becomes leaner overall, flab at the sides of your pecs sooner or later will exit the building.

To lose a pound of fat, you've got to create a deficit of 1,500 calories. A two-pronged approach is best: eat less and burn more with cardio training. High Intensity Interval Training (HIIT) is an effective way to accomplish that. HIIT means alternating intense bursts of activity with intervals of lesser exertion or complete rest. For example, you might jam hard on the treadmill for two minutes and walk for one minute.

Read More: How to Lose Chest Fat

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