• Matt Ferrara BS C.S.C.S

Understanding The Relationship Between Fitness And Fatigue

A good program is much more than just sets and reps over time. As things get more advanced, one of the most important programming factors is fatigue and fitness decay over time.

As your mother may have told you when you were younger, nothing good lasts forever.

Well she was technically half true. In reality, NOTHING lasts forever, good or bad.

Everything is heading towards a state of decay at it’s own pace.

Charming, I know. But it’s true.

Your fatigue and fitness levels follow the same rules, which is an incredibly important and often overlooked aspect of long term programming. The following will help you better understand how to program while taking these factors into account.

What are Fitness and Fatigue?

The relationship between fitness and fatigue is one of the most important things that needs to be understood when it comes to physical preparation and performance.

But first, let’s define these two characteristics.

Fitness: Fitness refers to the positive adaptations that drive you towards your performance goals. If your goal is to squat 500 pounds, the neural and physiological changes that occur as a result of strength training are fitness.

By the same token, increasing your long distance run time while still having the same squat goal is not considered improving your fitness.

Fitness is specific to the goal outcome.

Fatigue: Fatigue is the short term inability to express fitness to the highest level.

There are three main types of fatigue that result in a blunted ability to express strength and performance. These include central fatigue, peripheral fatigue, and muscle damage.

As opposed to occurring in isolation, fatigue are usually a combination of the above three.

Central and peripheral fatigue are the most transient, and do not last long once the workout is over. Central fatigue is the quickest to alleviate, usually dissipating within an hour of the training session unless accompanied by severe muscle damage.

Peripheral fatigue is caused by the accumulation of metabolites during the session, the effects of which are largely gone after a few hours. Again, this can be somewhat delayed based on what degree you smoked yourself and the type of training you performed.

Lastly comes fatigue caused by muscular damage. Strength and performance loss from muscular damage can last up to a couple weeks depending on the severity. However, it typically lasts only a few days before soon returning to baseline levels. Sessions that cause significant amounts of muscle damage are the most important to take into account when looking at short term fatigue and fitness management.

Examples of these training sessions are those with high volume and or emphasis on the eccentric portion of the movement. As a coach, you want to know that the athlete or client will have a significantly blunted expression of fitness for the following day or so. This is where aerobic capacity sessions or lighter skill days come in handy.

The Deleterious Effects of Fatigue And Fitness

We’ve already established what fitness and fatigue mean, as well as the concept that nothing lasts forever.

But what does this mean in relation to programming, and how can you use this knowledge to take your training to the next level?

First of all, there are a few more variables to the duration of fatigue and fitness than I mentioned before. These all boil down to how much of a stress signal you can send when


Factors that affect this stress signal are things such as training experience, strength levels, and the body mass of the lifter. Genetics also can play a role in how fast fatigue is dropped and how long fitness is maintained.

Trainees that are larger and have a greater strength level and longer training experience have the ability to cause more stress to their body. As a result, the fatigue they create lasts longer. However, the fitness that they build from training also sticks around longer. This allows them to have longer periods of maintenance time before having to revisit certain qualities once again to rebuild.

All other things being equal, the lifter who drops fatigue quicker and holds fitness longer will always have a slight advantage over others.

Potentiating Sessions:

The fitness-fatigue model helps make a case for the critical use of low volume and low fatigue sessions.

Let me explain.

A typical training week for one of my more advanced clients will usually start the week with a high volume session that results in quite a bit of residual fatigue for the next day.

Instead of adding in more high volume work the next day, I will typically program a lower volume day.

The goal of this session is to take advantage of the potentiating effects of the work we are about to do.

Potentiation is when short term increases in strength and performance are obtained immediately after a stimulus. This is typically referred to as the “post activation potentiation affect” when it occurs immediately after a set or a session, and is something many coaches and trainees will take advantage of.

However, these transient effects can also last hours or even a day or two after the session. As a result, these potentiating effects are typically one of the main goals of the sessions that I program after a stimulus day. The resulting effect is that they deliver a slight adaptation and allow us to train specific qualities more efficiently, while providing a potentiating affect for the next high volume or high intensity training day.

Know When To Push, And Know When To Rest

An understanding of fitness and fatigue as well as how your body responds to stress is critical when it comes to long term programming and training.

Use your higher volume sessions to send a stimulus, and lower volume sessions to manage fatigue and fitness and deliver potentiating effects for harder sessions to come.

It’s all about stress management.

If you need help setting up your long or short term programming in order to be most successful, reach out and let me know how I can help.

I look forward to hearing from you!

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