Basic Types of Training

It is important for you to be able to distinguish between compound and isolation exercises. These 2 basic types of exercises are used in weight training. The distinguishing features of these two types of exercises provide unique ways to work on our bodies.
A balanced combination of both types will optimize the effect of your training. And such combinations will gain in importance as you advance. A compound exercise involves the use of more than one joint. Such exercises require the use of many different muscle-groups to complete a single movement.
An isolation exercise, however, involves the use of just one single joint and one single muscle-group. A good example of a compound exercise is squatting. When doing knee-bends the hip as well as the knee-joints are used to carry out a single movement. An exercise like leg extensions, however, places the emphasis on the use of one specific part of the upper leg.
Although in both these exercises the thighs are trained, they nevertheless have a different effect. To perform the compound exercise, almost all the muscles of the upper legs are used, i.e. mainly the frontal part of the thighs (quadriceps), but also important muscles of the rear part (hamstrings and buttocks).
To perform the isolation exercise, however, just one single muscle is used without using any of the other muscles. The isolation exercise, then, mainly concentrates on a specific (isolated) part of the thighs.
Understanding the relationship between these combinations is essential for successfully developing your body.

Compound exercises are the backbone of every balanced bodybuilding routine. They contribute towards the development of your muscles in a way which cannot be achieved by the use of isolation exercises alone.
The compound exercises are also most important during the first stages of your development when you are striving to achieve total body development.