In bodybuilding, it’s not about moving the weight, it’s about building the muscle. In order to do that, tradition states you have to isolate the muscle to really focus on each contraction and achieve maximum motor unit activation. But is it really necessary, or are compound moves worth just as much on your journey to a bigger, more balanced physique?
Turns out, a muscle can be fully activated both when isolated and when contracting as part of a group of muscles acting together. There’s nothing in the anatomy or physiology of the body that requires a muscle to be isolated to fully activate it. Don’t buy it? Here’s some proof:
Studies using electromyography (EMG) to measure muscle activation have shown that compound exercises activate the major muscles involved in the movement as well as isolation exercises and sometimes better than isolation exercises.
Studies on untrained subjects show that compound exercises produce equal increases in muscle size and strength as isolation exercises.
Brazilian researchers compared two workouts in trained subjects: compound and isolation exercises and compound exercises only. They reported no differences between those who added isolation exercise to their workouts and those who didn’t.
Our verdict is that compound exercises are just as effective at building muscle size and strength as isolation exercises. Plus, they stimulate more muscle groups and reduce the risk of losing muscle symmetry that can occur when focusing too much on a single muscle group.
That said, isolation exercises should be used for specific muscles that need to be brought up or to reduce work for surrounding muscles that don’t need the extra work.
