How I grow my pecs with an exercise Arnold Schwarzenegger said helped him build his enormous chest muscles

This is an exercise I would never leave out from my push workouts; all you need is a pair of dumbbells and a weight bench

Shirtless Arnold Schwarzenegger displaying his enormous pecs muscles
(Image credit: Getty Images)

Arnold Schwarzenegger looked terrific in the 70s; this is an indisputable fact. Even now, 50 years later, we keep going back and analysing how he trained so that we can better understand how to build muscle efficiently (I sure do).

His pecs were particularly ginormous, and according to Arnie himself, there was one exercise he preferred doing to make them look so broad. It's the same pecs exercise I simply can't stop doing myself (although my chest is not nearly as big as his).

Before we go any further, it's worth noting that Arnie was a professional bodybuilder and worked out intensely almost every day. For example, the Arnold Schwarzenegger Blueprint to Mass workout plan involves doing countless reps of heavy exercises that include his famous Arnold press, as well as the pecs exercise we'll discuss today. Don't expect breastplate-like pecs nor a back as big as Arnie's after one workout.

According to Arnie, the dumbbell pecs fly is the best pecs exercise to build a massive chest. But not just any old pecs fly, but a brutally low pecs fly that opens up the chest and stretches the muscles to make them wider. At least, this is what Arnie and his contemporaries thought.

And looking at the Golden era bodybuilders of the 70s, they were probably not wrong...

(Want to know how Sylvester Stallone built his huge arms for Rambo 2? He used the help of two-time Mr Olympia winner Franco Columbu.)

Arnold Schwarzenegger Pecs Fly: How to grow your chest like a pro

From an equipment point of view, Arnie's pecs fly isn't all that different from your everyday dumbbell fly. All you need is a decent weight bench and a pair of heavy enough dumbbells (you can use adjustable dumbbells if you're working out at home).

Some might prefer multi gyms and cable machines in the gym to do this exercise; whatever floats your boat. If you're working out at home, you can perform standard pecs flys using resistance bands while laying on the floor, although you won't be able to open your chest up quite the same degree as Arnie does in the video above. Nevertheless, pecs flys are still worth doing however you can.

The key to growing your pecs like Arnie, as you can observe by watching the short video clip above, is to utilise the full range of motion of the pecs fly exercise. Arnold and pro bodybuilders of the era, such as Franco Columbu, used this deep movement to put the muscles under more pressure and therefore grow them quicker.

By not going quite as deep, you miss out on some of the most important parts of the exercise; it's like doing lat raises by only lifting your arms to 45 degrees. The first time I tried to replicate the Arnie pecs fly, I couldn't bring the dumbbells back to the starting position; they were too heavy for the movement.

After adjusting the plates (I used the Core Fitness Adjustable Dumbbell, so it was easy), I slowly lowered the weights to see how far down I could go. After a couple of slow reps, I started busting out proper, deep pecs flys and, boy, oh boy, my pecs were on fire.

Be careful, though: you'll need to stretch before the workout to be able to open your chest up to that degree. Not to mention, using heavier weights and performing this exercise without the correct form can also compromise your shoulders; a proper warm-up is crucial.

I recommend using lighter weights for the first set and always doing the first rep slower to prime your muscles and joints to what's coming their way. By performing the first rep slower, you can also reap the benefit of the slow eccentric movement, an essential technique to build muscle fast.

Fit guy performing the bench press exercise in a gym using a barbell

(Image credit: Getty Images)

Grow big pecs with compound exercises

A surefire way to enlarge your pecs is to do compound exercises such as the bench press or push-ups. (Here's how to do bench press and how to do push-ups). Compound exercises work a range of muscles while allowing you to build strength and muscle mass quicker.

The bench press is one of the most essential exercises to grow the pecs. Admittedly, you will need a barbell and some bumper plates to perform it in your home gym, but if you can't be bothered to store them in your living room, you can always visit a gym or do it there or use dumbbells instead of those at home.

There are many variations, and it's recommended not to do only that standard flat bench barbell bench press all the time; mixing up your workout routine with a narrow grip and incline press presses will help stimulate your muscles more, which leads to quicker muscle growth. Try this bench press trick for even more stimulation.

Push-ups are a low-cost alternative to the bench press, and according to science, it builds pecs just as well as the bench press. Again, you would like to make sure you don't just do the basics version and include different push-up varieties in your workouts (here are a few push-up variations). 

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Matt Kollat
Matt Kollat

Matt is T3's Fitness Editor and covers everything from smart fitness tech to running and workout shoes, home gym equipment, exercise how-tos, nutrition, cycling, and more. His byline appears in several publications, including Techradar (opens in new tab) and Fit&Well (opens in new tab), and he collaborated with other fitness content creators such as Garage Gym Reviews (opens in new tab).