Isolation and Compound Exercises
Some of you will now wonder what I meant in the previous article by multiple joint or compound exercises. Let me explain this with the example of biceps training.
A typical single-joint or isolation exercise is biceps curls on the preacher bench. In these exercises, the upper arm is in a fixed position and only the forearm moves across the elbow joint. This way the biceps is being isolated and has an easily defined “dead spot” at the position where the leverage is greatest, in this case the forearm parallel to the ground.
However, a multi-joint exercise for the biceps are chin ups. In this exercise, not only the upper arm moves to the forearm via the elbow joint, but also the upper arm to the trunk via the shoulder joint. In this way, not only the biceps are stressed, but also the back and shoulder muscles. Now you could argue that the load is distributed in this way to several muscles and thus the training stimulus for the biceps is reduced. But multiple tests have shown that it is not the case (see EMG-tests below), because the weight, which is moved with chinups, is clearly larger than with preacher curl. Ergo you not only achieve a training stimulus for the biceps, but also for the back and shoulder muscles. A single multi-joint exercise can thus replace multiple single-joint exercises.
Such examples can be found practically for all target muscles (Fig.1). But of course there is no rule without exception. Thus, there is no isolation single-joint exercise for the back muscles (a case can be made for elbow machine pull-overs). Due to anatomical structure of the human body, the arm flexor and shoulder muscles are always loaded when putting stress on major back muscles like the latissimus dorsi or teres major.
|Fig.1: Examples for Isolation and Compound Exercises|
|Muscle Group||Isolation Exercise||Compound Exercise|
|Biceps||Barbell curls, preacher curls||Chin-ups, supinated pulldowns|
|Triceps||French press, kickbacks||Dips, close grip bench press|
|Shoulders||Front and lateral raises||Overheadpress (OHP)|
|Back||—–||Barbell rows, deadlifts|
|Latissimus||(Machine elbow pullovers)||Pullups, chinups|
|Chest||Pec deck, dumbbell flyes||Bench press, dips|
|Quadriceps||Leg extensions||Squats, leg press, hack squat|
|Hamstrings||Leg curls||(Stiff-legged) Deadlifts|
As a rule of thumb, all basic exercises are also multi-joint exercises. They have a primary muscle that needs special stimulation, as well as secondary or auxiliary muscles that still experience a strong training stimulus, but are still stressed less than the primary muscle. As mentioned before, there is no rule without exception and here are two of them: biceps and triceps.
The only multi-joint exercise that could be regarded as a targeted biceps exercise are chin-ups with a supinated grip. But even here the target muscle is the latissimus of the back while the biceps still is being strongly activated, but only as an auxiliary synergistic muscle.
Triceps training can be trained with dips or close grip bench presses. Although the triceps are being loaded heavily, the target muscle and primary mover is the chest (Pectoralis major), which, in this exercise, is usually depleted and exhausted first, before the triceps. Although, at least in the case of dips, variations in form and range of motion (for example, bench dips) may place the strain even more on the triceps, the shoulder still takes on larger portions of the chest work.
For basic exercises, barbell and dumbbell curls are widely used in biceps training, as well as the French-Press (also known as “skull crushers”) in triceps training. These are staples which are not multi-joint exercises but typical isolation exercises for getting the job done. For the beginner, however, dips and chin-ups are sufficient enough stimulus for arm growth in the first three to six months, sometimes even the first year.