man on an incline bench press
Inside The Gym

Why Compound Exercises Build More Muscles

2 min read

When exercising to build muscles, it’s typically advised to focus more on compound exercises while isolation movements are reserved as accessory lifts. The reason for this is because it’s widely accepted that compound exercises give you more bang for your bucks, in the sense that big movements produce more (and better) results than small ones. But why is this?

If you’ve ever found yourself questioning if compound exercises build more muscles or wondered the logic behind it, then read on.

More Muscle Group Recruitment

Logically, more muscles exercised means more muscles growing. And complicated movements require more muscle involvement to pull them off. Think of the big lifts like deadlifts, bench presses, and squats; each one incorporates primary and secondary (and even tertiary) muscle activations in their movements, whereas isolation exercises focus in on key muscles (think leg extensions, biceps curls, shoulder shrugs, etc.), effectively targeting smaller, more precise areas.

Hell, it’s even in the names: compound exercises and isolation exercises. One type involves multiple muscle groups, and the other involves zeroing in on a specific muscle group.

Allow for Heavier Weights

When dealing with isolation exercises, the number of weights you can shift is naturally smaller than compound exercises (due to the differences in how many muscle groups are utilized between compound and isolation exercises). With this in mind, shifting heavier weights means more stimulation to the muscles worked, therefore compound exercises, which allow for heavier weights, stimulate your muscles more than isolated exercises where you can’t go as heavy.

Fact is, it’s not a coincidence that the movements where you can lift the greatest number of weights involve more of your body. The body is such an intricate, amazing instrument.

Stimulate Testosterone Production

Testosterone is the key hormone that develops muscles, and the more muscles you work the more testosterone your body produces. Alongside doing compound exercises to produce greater testosterone stimulation, this is also why back and leg exercises are loved by masochists – they recruit a lot of muscles in their respective exercises, therefore, driving up your testosterone levels.

Isolation Exercises Serve a Different Purpose

Compared to compound exercises, for the previously stated reasons (muscle recruitment, heavy weights, and testosterone levels), isolation exercises aren’t primarily about growing muscles. This is why they work effectively as accessory exercises. More often than not, the purpose of isolation exercises are to: complement/develop another exercise, further work lagging or injured body parts, or even act as post (or pre) pumps for other exercises (that is, warmups and finishers, for the uninitiated).


A writer, gamer, geek, and gym rat all packaged into one. I'm a certified personal trainer who writes about the things he loves and I enjoy sharing them with others all on MXFitness.