The Ultimate Guide To Training Principles
The Training Principle Of A Varied Stimulus
The Training Principle Of Varied Stimulus, also known as The Principle Of Variation, is one of the most misunderstood principles of training. When most people hear variation, they think about varying exercises. Unfortunately, you can’t be more wrong.
In this article you’ll learn
- Why to not call it the principle of variation
- The basic premise of the principle of a varied training stimulus
- The biological basis of the principle of varied stimulus
- The practical application of a varying training stimuli
- Rounding up the training principle of a varied training stimulus
Why not call it the principle of variation
I have discussed in previous lecture, that the main objective of training is to set a stimulus in order to elicit adaptions.
I have told the story of Prometheus who stole the fire from Zeus, and as a punishment, Zeus chained Prometheus to the cliffs. Every evening an eagle came to pick out the liver of Prometheus. overnight the wound healed and the next day the cycle repeated, so, the eagle came again to pick out the liver and the wound healed overnight again.
This is in essence a good example of the human body’s ability to adapt.
I also outlined in a previous articles that the goal of training is to stimulate not annihilate . And I outlined my model of different training zones, the ‘ideal training zone’, the ‘no pain, no gain training zone’, and the ‘pointless training zone’.
Calling this principle of training ‘the principle of variation’ is misleading, because it puts variation in the focus and you can vary your training until the cows come home without ever setting the stimulus.
You can vary your training until the cows come home without ever setting the stimulus.
Therefore, I prefer calling it the principle of a varied stimulus, because you want to set a stimulus. A small, but important distinction.
The basic premise of that principle, the principle of a varied training stimulus
Training must be varied in order to continuously set new stimuli.
What can be varied?
When hearing variation, most people think of varying exercises. The origin of that thought is probably from one of the fundamental bodybuilding principles, the Weider Principle of Muscle Confusion, where the premise is to change exercises, as the stimulus to muscle growth.
But the main training variables that actually should be varied isn’t the exercise selection, but much rather
- the training intensity
- the training volume
- training duration
- training density
- and training frequency
What’s the biological basis of the principle of a varied training stimulus
I have outlined the graded response rule in the previous articles, which says the training stimulus has to be above a certain threshold. An optimal stimulus invokes the desired adaptation, a too high stimulus has an impaired adaptation, and a stimulus that is too low leads to no adaptation or de-adaptation.
You learned about the parabolic time course of adaptation, and the simplified model that shows that if the stimulus is not progressive, the adaptive response decreases. A high stimulus will become a moderate stimulus, will become a low stimulus overtime, if training is not progressive.
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The practical application of a varied training stimulus
As I’ve outlined above, the main training variables are training intensity, training volume, training duration, and training density.
And if you look at the most fundamental bio motor abilities, strength, speed, and endurance, you can see how to vary the main training variables for the fundamental bio motor abilities.

How to apply the main training variables (training intensity, training volume, training duration, training density & training frequency) to the main bio-motor abilities strength, speed, and endurance.
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So, if you look at this training principle of a varied training stimulus, you can see that it has a lot of commonalities with the training principle of optimal stimulus, as well as the training principle of progressive overload.
Therefore, this principle of training is a very good example, of how training principles can overlap, and / or complement each other.
Rounding up the principle of a varied training stimulus
I outlined why not to call it the principle of variation, because training is about setting a stimulus to elicit adaptation, therefore it should be called the principle of a varied stimulus.
In order for a stimulus to elicit adaptations over time, it has to be progressive, and it has to be varied through the main training variables training intensity, training volume, training duration, training density, and training frequency.