!-- Intensity!
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One of the key variables in exercise is intensity, often regarded broadly as the effort put into performing a giving routine. Yet, the role of intensity in resistance training is not always so clear cut.

Anything less than sufficient intensity in effort, even while incorporating lifestyle changes as part of well-rounded diet and training program, can quickly result in a plateau, or a noticeable failure to progress. On the flip side of the same coin, too much or too frequent use of maximum intensity can bring about the same undesirable results.

The amount of resistance and the duration of the activity can all be calculated with a high degree of accuracy, of course. The factor subject to the greatest degree of variability is -- you guessed it -- intensity. And it's intensity that should be considered the cornerstone on which we build our entire training and dietary regimen. With that in mind, let's look at intensity and its effects on size and strength training.

Defining Intensity

What does intensity really mean? A standard dictionary definition for intensity is a degree of strength, energy, or force. An alternative definition in Webster's is "the magnitude of a quantity (as force or energy) per unit (as of area, mass, charge, or time)". Yet both definitions are still quite vague for the purposes here.

With respect maximizing the results of a given regimen for an increase in size and strength, one's desired intensity level could be more accurately defined as "the degree of effort used sufficient to impose the controlled stress of the greatest number of muscle fibers in the target muscle group, causing a maximal amount of repairable damage".

This all might seem more complicated than it really is. Let's take a closer look at how this works at the neuromuscular level.

Contractile Intensity

Contractile intensity is regulated by the action potential thresholds of different motor units (or bundles of muscle fibers). In more simple terms, such bundles are triggered to contract only when the nerve impulse reaches a certain threshold. Those bundles with the highest thresholds are the last to be recruited, hold the greatest potential for growth, and will not contract with anything less than maximum intensity. What's more, these high-threshold bundles have a comparatively small energy storage capacity, meaning they can only function optimally for short intevals. This means that prolonged workouts using high intensity are unnecessary, cause more damage than can be effectively repaired, and are inherently counterproductive.

In every muscle group, there are hundreds, and in some cases, thousands of such motor units. In order to maximize the level of growth stimulation in a given muscle group, the goal should be to involve all of these units.

This process of performing sets to absolute failure is a tall order, indeed. However, keep in mind that with each repetition, more and more tissues will be recruited. With heavy resistance, more fibers are working early on in the set, immediately calling for the involvement of a greater number of high-threshold motor units. 

Here, care should be taken to cause only the amount of damage that can be repaired before attempting to train that specific muscle group again.

In performance terms, that means that doing heavy singles and doubles, forced reps, negative reps, strip sets, super-sets, giant sets, etc., may cause too much damage, and in most cases should be avoided -- with the following exceptions:

  • While allowing extended between workout recovery periods (4-5 days) for target muscles. This allows for a more complete repair of the severely damaged muscle tissue resulting from the above types of training. 
  • By infrequently implementing only a few sets of the above mentioned types of training, target muscle groups can recover completely prior to being trained again.

Pace Yourself

As we know, giving anything one's best effort in a short period of time comes at a price. An analogy from the world of aerobic exercise would be to ask a world-class sprinter to run back-to-back 100 meter dashes with maximum effort. It is to be expected that even this finely tuned athlete's performance in the second race will suffer. The same thing applies to working out in the gym.

Attempting to use maximum intensity in every set of a prolonged workout quickly diminishes one's performance level, and as a consequence is counterproductive by exhausting too much energy and causing far more damage than can be repaired. Remember, keep things short, sweet, and to the point!

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