This is a basic principle, that revolutionized the bodybuilding training methods. Muscles can work as synergists, antagonists, stabilizers or separately. During the basic (compound exercises) the muscle groups work together, without being able to differentiate the participation of the separate synergists.
Something more to it, during the progressively increasing fatigue the individual unconsciously transfers the tensity of the heavy workload, by changing the grip, working position and using inertial movements to the relatively stronger muscle groups, by which they unconsciously increase the muscle disproportion, initially strength wise and muscle size-wise in the long term.
That is why the isolation principle is pointed directly at the main goal of bodybuilding- Harmonic physical development, the reason being- it is mostly used for the lacking muscle groups. It is easily doable for the muscles on your limbs (Bicep, triceps, quadriceps, hamstrings, calves) and fairly harder for the Chest, back, shoulders and glutes where the use of specialized gym equipment is required.
Advanced trainees perfectly know that the potential increase in strength, for the isolated exercises is fairly lower than the one for the compound exercises.
Many people managed to increase their strength for the compound movements 3, 4 or even more times (eg- They started with 30 kg on the bench press, and a few years later they can lift 150 kg for reps).
However, at least in our experience we haven’t seen a person who started with 30 kg on the exercise “barbell curl” and progressed up to 120 kg. Of course, to each rule there’s an exception, but we’re talking about the general population.
There are a couple of reasons that explain this.
If we look back and analyze the exercise “flat barbell bench press”, we will conclude that the main muscle groups involved during this movement are – The pectoral muscles (Chest), triceps and front deltoids (Shoulders).
Researches show, that the increase of strength for each muscle group is about 2 to 3 times more than the starting point.
So how do we overcome 4 times bigger weights for the compound movements?
The answer is – Muscle synergy.
As a whole, increasing the strength is done by developing the contraction and relaxation, between the activated muscle groups and stabilizers.
Compound movements, of course, are a strong tool for most bodybuilders, but sometimes they don’t apply to the bodybuilding requirements.
Isolated movements are the only method that allows trainees to concentrate all their physiological and psychological capabilities in one spot, therefore the local muscle-energetic use is most efficient.
That is due to the fact that during compound movements, the stress upon the weakest muscle group involved, ends when it reaches failure. That way, the other muscle groups, that are synergists, do not reach the desired muscle efficiency.
From this we can conclude, that in order to build or shape a certain muscle group, it must be isolated from the other synergists in the best way possible.
How to Isolate the Muscle?
This can be a hard task at times.
A few ways we can do it-
1- Using specialized gym equipment
2- A change in position, that excludes synergists or inertial movements.
Focusing your attention on the muscle group during an exercise, gives psycho-physiological benefits for the full mobilization and activization of the muscle units. Something, that is fairly harder to achieve during compound exercises.
This can easily be felt by doing a bicep curl with a dumbbell, done separately on each arm, rather than doing it with both hands simultaneously.
As we said earlier, for the limbs, you have a way bigger window for isolated movements, compared to the muscles on your torso. The reason being- In order to isolate the chest, for example, we have to exclude the muscles on our arms by blocking the elbow extension, this can only be done with specialized gym equipment such as a pec deck machine.
After all, despite the fact that the isolation principle has a huge room for application in a bodybuilding workout, we have to evaluate its effectiveness compared to the compound movements.
All of that will help us build the optimal training regimen, that is a combination of both isolated and compound movements.
Before doing that, though, you have to know what your current goal is at this stage, due to the fact that the variety of goals you can have is huge. You might want to increase your muscle size, strength, separation, leanness or simply overcoming the negative adaptation (plateau).
Below is a classical scheme you can use, to see which principles to apply, depending on your goal.
You can look at this scheme, when you have a hard time deciding what to use, once you have acknowledged your goal.
GOAL TOOL TO USE
1- Hypertrophy, strength – Basic (compound) movements
2- Leanness, separation- Isolated movements
3- Overcoming plateau- Mainly isolated
The compound movements, during which a couple of muscles are used at once, done with a full range of motion, burn more energy for a unit of time, compared to isolated movements, with which they help the process of fat burning.
Even more to that, not only do they shape the involved muscle groups, but they also aesthetically highlight the border area between muscles, in other words- you get a naturally looking, pleasing separation.
For example, the link between the glutes and the hamstrings is effectively worked on not by isolating movements but compound ones like glute ham raises and Romanian deadlifts.
Below, we will show you some isolated movements for each muscle group.
Exercises in Which We Use Specialized Gym Equipment
Bicep cable curls
Machine preacher curls
Triceps dip machine
One arm cable extension
Pec deck machine
Reverse pec deck
Ham curls – laying
Standing/seated calf raises
Leg press calf raises
Free Weight Exercises
Preacher curls- barbell/dumbbell
Concentration curl- dumbbell
French press- barbell/dumbbell
Front/lateral dumbbell raises
Laying ham dumbbell curls
Standing/seated barbell calf raises
Donkey calf raises
All curls and twists done on a board, wall, chair, pull up bar etc.