Compound VS Isolation Exercises (Your Definitive Guide)

Let the battle begin.  Compound vs Isolation Exercises.  Want to know which is best for building muscle? Then this is the article for you.

When it comes to deciding which form of exercises are best, compound or isolation, the only thing you have to ask yourself is, What are you trying to achieve from your weight lifting?

Well, I don’t know about you but what I’m trying to achieve is increased state of muscle tension, muscle growth and strength. If this is the same for you, then the only way to maximize all of these is through compound exercises.

I constantly hear people talking to their training buddies about how much their arms burn after doing that 20 rep set and how pumped they are.  Well as good as these can feel and as good as they can make you look throughout a training session, muscle burn and muscle pump do not stimulate muscle growth.

The only way to stimulate muscle growth is through progressive overload.  This is exactly what all my own and client’s training is based on.

There has to be a reason for your muscles to grow, as once we are adults this does not occur naturally.  As stated before, that reason is progressive overload and the more overload the muscles are put through, the greater increases in strength and size you will experience.

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Compound Exercises Explained

When we talk about compound exercises, we are referring to a movement that involves more than one muscle group and joint.

Let’s take the squat as an example.  The main muscles involved include the quadriceps, glutes, and hamstrings.  And the main joints involved include the hips, knees, and ankles.

If we compare this to an isolation exercise like the leg extension, both are used to target the quads, but with the leg extension, the only muscles being properly stimulated through are the quadriceps.

Due to the singular movement of the knee joint and the quads being the only muscles worked forcefully enough, the leg extension cannot be classed as a compound exercise.

We now know progressively overloading the muscles is the only way to make them grow, and compound exercises are the best way to make this happen.  Below you will find the main reasons why.

#1.  The Amount Of Weight You Can Put Through The Muscle

Compound exercises allow you do put so much more weight through the targeted muscles.  For example, you may be able to flat dumbbell press  50kg for 4 repetitions before reaching positive failure.  Now if you tried to do a flat dumbbell fly with the same weight for 4 repetitions, you will soon realize this is near impossible.

In fact, good luck trying to do just one strict repetition.  In order to hit 4 reps to positive failure on a dumbbell fly, you would have to drop the weight considerably.   This then links into the amount of overload that is created through the targeted muscle.

pec flye

bench press

#2.  Growth Hormone and Testosterone levels are significantly raised

There have been studies done showing that compound exercises produce far greater increases in both growth hormone and testosterone levels.

Although they don’t have as big of an influence as many people would make out, they are still vitally important when it comes to muscle growth.  And if you have increased levels in both then that is always a huge positive.

#3.  The Number Of Muscle Fibres Stimulated

Let’s get back on track.  Finally, compound exercises stimulate so many more muscle fibres in one hit.  By doing isolation exercises you are just expending energy and not really getting much back for your efforts.  Taking our dumbbell pec fly for example again, you are pretty much just working the chest muscles.  yes, a few other muscles are having to do some of the jobs as well, but to such a minor degree you will gain no benefit from it.  Now if we take our dumbbell bench press, you are working the chest, shoulders and triceps to a great degree, therefore stimulating so many more fibres.

#4.  The Amount Of Overload Created Through The Targeted Muscle

What do you think puts more overload through the chest, a 50kg dumbbell press or a 25kg dumbbell fly.  Now the latter may burn a bit more and you may be able to put a little bit of extra squeeze through the muscle but as indicated earlier, muscle burn is not an indication of muscle growth.  In fact, it can have a negative effect.

Why Muscle burn is not a good indication of growth

Muscle burn that is generally brought on by high rep isolation sets is a build-up of lactic acid in the muscles.  Lactic acid is a byproduct produced when your muscles outstrip your heart’s capabilities to shunt oxygenated blood into the muscles.

Lactic acid can actually impair muscle growth, and one of the reasons for this is it can severely overwork the central nervous system, which then causes delayed muscle recovery.  Also doing the high reps sets usually associated with this do not supply sufficient overload to the muscles.

Should Isolation Exercises Have A Place In Your WeightLifting Program?

compound vs isolation exercises. Muscular male doing a straight bar bicep curl

There is always going to be a large percentage of gym-goers, especially strength athletes and powerlifters, that will tell you Isolation exercises have no right to be in any kind of weight training program.

That you should only be squatting, deadlifting, bench pressing, and overhead pressing to achieve that killer body you are after.

I couldn’t disagree with this more.

When doing a compound movement, there is always a muscle that acts as a prime mover.  Basically, the muscle doing most of the grunt work and that will benefit most from the exercise.

However, each compound exercise will always have other muscles working to assist in the movement.  The difference being, they won’t be doing anywhere near the amount of work as the prime mover.

So this means there is a high chance you could develop muscle imbalances from just doing those big compound lifts.

Let’s look at a couple of examples.

You have planned out your shoulder day and it’s made up of 3 big pressing exercises.  This is actually very common.

Now there is a major problem with this.  It will be very difficult to achieve a fully developed looking shoulder.  You know that impressive rounded and capped look, that gives the impression the shoulders are popping off the arms.

So why does this imbalanced look occur when only doing pressing movements for developing your shoulder.

First things first, it’s important to understand how the shoulder is made up.

There are three parts to the shoulder

  • The front deltoids (anterior
  • The mid deltoids (lateral)
  • The rear deltoids (posterior)

So now let’s look at the overhead press.  When doing this movement the prime movers are the front deltoids.  After this, the mid deltoids are assisting and the rear deltoids are pretty much non-existent.

Here lies the problem now.  The rear and mid delts are mostly responsible for giving our shoulders that 3D look and not the front delts.

So having a strong overhead press is fantastic, but remember we are also trying to improve the look of our physique so haveing your delts popping out giving off that wow factor is also vitally important

This is where doing rear and mid delt isolation exercises to attack those hard to activate muscle comes in.

Above is one of the main reasons you should include isolation exercises, however, there are of course many others

It’s vitally important you follow a well-designed program that does include both compound and isolation exercises.

Compound exercises should make up 80% of your training routine, for all the reasons above and isolation exercises around 20%, in order to help you develop weaker looking areas that are not trained sufficiently by the compound exercises.

Compound vs Isolation Exercises Key Takeaways

  1. Compound exercises cause the greatest overload
  2. Compound exercises allow you to stimulate many muscle fibres in one go
  3. Compound exercises allow you to put the most weight on the targeted muscle
  4. It’s important to still include isolation exercises as these can help you develop weaker areas and help you in avoiding muscle imbalances
  5. Compound exercises should make up 80% of your program
  6. Isolation exercises should make up 20% of your program
  7. Muscle burn is not an indication of growth

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