Contrast Principle

Anatomy researches on the skeletal musculature

According to anatomy researches, during the last 30 years, the skeletal muscles consist of two main types of muscle fibers- Fast-twitch muscle fibers (white) and slow-twitch muscle fibers (red).

The ratio of white to red muscle fibers is genetically predetermined. It is also important to note here, that fast-twitching fibers can’t transform to slow-twitching fibers, and vice versa.

Even though this is still an object of discussion, among scientists and researchers of the human anatomy, it is undeniable, that the development of the white muscle fibers, takes place during high-intensity working loads, while the red muscle fibers respond best to an endurance-focused workout.

Types of fast muscle fibers

We can differentiate two types of fast muscle fibers- A and B.

The fast A fibers are mainly intermediary units between the slow and fast B fibers. They also use anaerobic processes in order to absorb glycogen, that is synthesized by the carbohydrates our body gets from the food we eat.

The fast B fibers are the faster, more explosive fast muscle fibers. They get activated when we use 100% intensity, using the energetic substances in our muscle as a fuel, without secreting lactic acid.

We should note here, that practically, when we do a set until failure, using 80-85% of our 1RM, the effort we apply for the last rep is pretty much equal to the effort we would apply during a one-rep max, 100% intensity set. Therefore, we can conclude that this is the point, where our body activates the fast B muscle fibers.

Activating the fast B fibers

There are a couple of conditions when it comes to activating the fast B fibers.

  1. Applying maximum will power and effort for each separate set of 100% intensity- this however, can not be done in more than 1-2 sets per exercise.
  2. Perfect warm up and stretching of the musculature and the nerve system.
  3. Optimal endocrine (hormonal) system activation.
  4. Starting off with a fully recovered musculature.

The white B fibers are quick to use all of their fuel, and just like the other fast twitch muscle fibers, they do not use oxygen to produce energy, which makes them anaerobic-lactate.

We can note here again, that the ratio of fast/slow fibers varies for the separate individuals, and the muscle groups are always a mix of both, as there is no scientific evidence, of a muscle group that is made completely out of just one type of fibers.

The ratio of fast/slow fibers in the upper body is pretty much equal, however, for the lower body, the slow ones are superior in number.

Besides the fact the white muscle fibers have a way bigger hypertrophy potential, bodybuilders can not afford to neglect neither of them.

This just goes to show that we should have a wide variety of rep ranges to use (from 2-3 reps to 20-30 reps and more), depending on the period we’re in. (Off-season, transition, or on-season period)

Using modern day sports medicine, we can accurately determine our genetic potential for certain sport disciplines, which is very valuable information, that can let us know, what the most potent training methodology would be.

The separate individuals use a different number of repetitions, during their workouts, depending on their individual characteristics and their musculature.

So, for example, we can give the arm workout of a well-known bodybuilder, namely “Mohammed Benaziza”, who used 15-20 repetitions, compared to “Geir Borgan” who used 6 to 8 reps.

Bigger differences can be noted in Flavio Baccianini’s leg workout, where he used 30 repetitions, compared to Sharon Marvel’s 6 repetitions.

Here, we can note that if you mechanically translate elite training methods and principles into the workout split of a beginner, there would be a negative outcome 99% of the time. (Of course, as we’ve mentioned, there are genetic freaks that would be an exception to this rule, but we’re talking about the general population here.)

As we already said many times, for beginners and advanced athletes, the most potent and effective workout would be an intense one. The explanation behind this- Lower reps require relatively higher weights, which create a stimulus for growth of the most hypertrophy-potent muscle fibers, namely the fast (white) fibers.

The need of change however, can be significantly noticed with athletes, that have 8-10 and more years of training experience. This is due to the fact, that no matter how hypertrophy-potent the white fibers are, they too have their limit.

In this situation, trainees aim for activation of all the muscle fibers, which requires not only an increase in reps and a decrease in working weight, but also an even pace during the exercise, that would grant a minimum lactic acid secretion.

This is where we logically reach the explanation, as to why bodybuilders use relatively low intensity, besides the high intensity, during the off-season.

So that’s how they practically apply the Contrast principle, not only as a tool for de-adaptation, but for muscle hypertrophy as well.


The contrast, as a bodybuilding principle, correlates to the principles of de-adaptation, priority, eclectic and instinctive training.

The strive for an often change in intensity, practically puts the musculature in a situation of stress (de-adaptation), and the optimal combination of the difference in intensity workloads, as well as building and shaping exercises, points the bodybuilding preparation in the needed direction (priority, eclectic) and realizes the ideas of the contrast principle.

At the end of the day, this type of ‘experimental training activity’ would help the trainee realize their strong and weak points – instinctive principle.

The contrast principle is best realized, through almost every bodybuilding method, but mainly- Pyramid, stop-rest, prolonged sets, drop sets, etc.

The conclusion here would be, that the contrast principle goes to show the big difference in training principles and methods, for advanced and elite athletes, compared to beginner trainees.

Which is why it would not be a good idea to copy the workouts of top bodybuilding champions, fitness models, competitors, etc. Due to the fact their workouts are strongly adapted to their individual characteristics.

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