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Fitness Fatigue Model: The Theory of Deloading

Posted by Issac Ishak on

I’m going to let you in on a little secret.

You don’t have to absolutely destroy yourself in the gym to build a great physique- in fact, that might actually hinder your progress. ⁣The gym is about stimulating adaptation, not about doing the most damage possible. It actually takes a lot less work and effort than you think, at least if your measuring stick is the physique athletes you watch on Instagram.⁣

Needing a wheelchair after a leg workout is not a prerequisite for gainz. Neither is being unable to comb your hair for a week after training upper body.⁣ Yes, you still have to work hard if you want to build something phenomenal, but you don’t have to go full potato with intensifiers, bands, chains, handcuffs, gun powder, insane volume, cosmic drop sets, or whatever other special technique or additive you imagine.

The Fitness Fatigue Model

The fitness-fatigue model as it relates to training explains the curve above by explaining the sum of two curves. One curve representing fatigue, the other improvement in fitness. Think of fitness as our maximum ceiling for strength capacity at any given movement. Long term progressive overload can raise this ceiling with time. Fatigue is the recovery cost associated with any effective training stimulus and external stressor. What we oversee as the expression of performance/capability in sport is based on the relationship between the two.

Once the fatigue effect has dissipated from a particular stimulus it’s possible to see the fitness adaptations, although the fitness improvement or adaptation begins after the end of a resistance training session. Without this proposed model, we would begin to believe that fitness adaptations take place after a few days due to the reduction in performance. The actuality is adaptations begin to occur after a given session. For example strength-trained athletes, a good majority of the adaptations in the central nervous system occur the same day as the workout (1). Improvements take place in the central nervous system occur inside the muscle tendon unit that ultimately improves force production. The exact changes that occur in the central nervous system depends on the type of stimulus, and this variability is what underpins the principal of specificity in resistance training. Moreover, muscle growth is stimulated via an increase in the rate of muscle protein synthesis, that begins falling after 24 hours (2).

Potentiation which is the increase strength of nerve impulse along pathways, occurs immediately after a workout, this is referred to as ‘post activation potentiation’. This doesn’t mean this process only occurs post workout, it can also occur hours or even days after a session. With this understanding we can conclude that there are both short term and long term adaptations that occur as a result of resistance training.

We only have so much control over the stress side of the equation in regards to training. Big picture, we don’t have control over the magnitude of external stress such as relationships, work, parenthood, etc.. Which can all impose additional layers of stress. Thus, the fatigue sided of the performance equation is largely dependent on factors which are outside our control and not directly related to our input from the fitness side of things. We most cope with external stressors that manifest as accrued fatigue and compounded fatigue already present from training. Moreover, fatigue can’t be quantified, there’s no unit for fatigue, like there is with counting your macros, or steps. That being the case, it’s like smoke in mirrors trying to optimize and predict performance.

The Theory of Deloading


The SRA principle to explain the adaptation process. SRA stands for stimulus, recovery, and adaptation- It's basically just a fancy sports-science term describing how our bodies respond to training.


The idea of deloading starts with the fitness fatigue model. This theoretical construct starts with a reduction in performance following a resistance training session. The human body is amazing, but despite our biological similarities we’re all wired differently. Just because someone looks good, doesn’t necessarily mean they know what they’re talking about. So although someone may preach ‘x’ approach works for me, that approach might not work for the majority. Overtime we tend to get a better feel for our ‘readiness’ to train, or how well recovery-status is. Our ability to train is totally dependent on how well recovered we are— keep in mind per session performance is influenced by: sleep, mood, emotional status, hormonal status, and immune system function.

Now, depending on the magnitude and intensity of the stimulus it can reduce performance following a workout, or a few days after, it depends on different variables, but ultimately, after the initial reduction in performance, there’s a rebound. Session performance at any period of time is a function of previous training adaptations, this leads to a state of fitness, and fatigue. Performance improves by producing adaptations that improve fitness (training), or by managing fatigue by deloading or tapering. The rationale is to temporally dissipate residual fatigue, and bring stress back down to baseline in order to maximize performance at a later time. 

A deload, as it relates to training, is a reduction of one or multiple stimuli for a period of time. It is more than just decreasing variables such as the number of sets or perceived effort. For example, this could look like a reduction in set volume, intensity of effort, rotating exercise selection, lighter loads, or simply, a combination of them. Intelligently utilizing deloads is valuable and essential for speeding up our ability to make progress and avoid training plateaus. A deload doesn’t mean absolutely no training, although sometimes that is exactly what is needed. It all depends on what stimulus you’re trying to take a break from, you may have to change one, or several variables of a workout.


The body is designed to adapt to physical stressors as a survival mechanism. We use this to our advantage when we train to create desirable changes to our physiology. Increased muscle mass, more efficient nervous system, improved endurance and stamina are all adaptations to the stimulus we create when we train.

However, subjecting your body to the same stimulus for too long will decrease the rate at which we can adapt. By implementing a deloads, a break from a given stimulus, you will desensitize your body to that stress. This doesn’t mean you will totally lose your adaptations, but simply that when you reintroduce it you’ll start responding again almost as quickly as when you first began.

Decrease Inflammation

Inflammation can be a result of many factors and is not always a bad thing. The exercise (which is a stressor) actually damages your muscles, and increases levels of oxidative stress and inflammation in the body. You’re actually getting a relatively low but manageable dose of stress and microtrama or microtearing of muscle fibers the sheath around the muscle and connective tissue (which you might feel in the form of soreness or DOMS [delayed onset muscle soreness]). When your body heals those tiny injuries, it builds up new muscle fibers to go along with the repaired tissue.

In your next workout, you might be able to squat the bar for 5 sets of 6, or you could go for the bar + 5 pounds (50 pounds total) for the same 5 sets of 5. Either way, your body adapts, becomes stronger and your work capacity improves. Then you go home, eat, get enough sleep, and repeat the cycle. In the long run, your levels of oxidative stress will decrease while you get stronger and more resilient to oxidative stress in general. Acute inflammation is part of a healing response from the body. However, excess or chronic inflammation can slow down your ability to recover, build muscle, and lose body fat. Subjecting your body to oxidative stress or muscular mechanical damage from training is inflammatory.

To an extent, this is good and part of the adaptation process that we are looking for. You might notice it as soreness (a.k.a. ‘DOMS’ Delayed Onset Muscle Soreness) for a day or two after training. Eventually the stress may be more than your body can recover from and the positive benefits may begin to decrease while other less desirable symptoms begin to manifest. Taking a break from a training stimuli can allow your body to bring down cellular inflammation which will result in several potential health marker improvements; faster recovery, increased glucose sensitivity, decreased subcutaneous water, improved pumps during training, and better quality sleep. It also means that when you reintroduce these training stimuli, you’ll be able to reap much more of the beneficial adaptations.

Promoting Detoxification Processes

Certain types of training demand a large supply of your body’s resources to run recovery processes. Your body will naturally prioritize those as it deems them necessary for survival. This can result in other processes either to take place less frequently than is optimal, or at a slower rate. Over time this can be detrimental to your health, both on a cellular and systemic level. Backing off on training that stimulates metabolically expensive pathways, like protein synthesis, will allow the body to utilize its available micronutrients to run essential processes such as detoxification and removing cellular waste.

Parasympathetic Dominance & Nervous System Recovery 

Resistance training is an extremely neurologically complex activity. It also results in a shift from parasympathetic (a.k.a. “rest and digest”) to sympathetic (a.k.a. “Fight or flight”) dominance. A sympathetic state is a stressed state. Hormones like cortisol and catecholamines are elevated, while non-essential systems (like digestion) are essentially halted as the body is in survival mode. While this is necessary for performance and some adaptations, it is not a state that we want to be in a majority of the time. As soon as training is over, or the “danger” has passed, we want our nervous system to return to a parasympathetic and relaxed state as quickly as possible.

Repetitive high-intensity training without adequate rest can result in the body never truly getting into a fully parasympathetic dominant state. This will inhibit recovery both for your nervous system and other recovery processes. Depending on the intensity and systemic demand of a workout, it can take several days for the nervous system to fully recover.

Mental Health

Sometimes we just need time to live life. As much as we are all passionate about training, we shouldn’t live to train but train to enhance our enjoyment of life. Occasionally taking a few days completely off from working out and enjoying time with family, friends, or other activities you enjoy can do wonders to improve your health and well being. The decrease in physical and mental stress can have profound effects on how your body looks and how you feel.

To conclude…

Find your lowest and highest effect volume and work in that range. Stick to basic, fundamental movements. Take a big dose of patience. Find a coach that understands training theory and emphasizes progressive resistance in the basic exercises that have worked since the beginning of time, and will work until the end of time. 

To bounce back and get stronger, we have to keep the “dose” of stress reasonable and actually give our bodies time to recover. Rate of recovery is dependent on our Allostatic Load (i.e. total stress you’re under at any given moment) this includes external stressors like your job, relationships, lack of sleep, chronic calorie restriction, nutrient deficiencies- to name a few.

Under-recovering, or Allostatic Overload can transform any stress into an unwanted-stress, regardless of how beneficial it could have been under the right circumstances. The harder you push, the more seriously you need to take recovery- otherwise what you're doing will wear you down.

Recovery means prioritizing sleep, nutrition, smarter training and not going balls-to-the-wall one side of the equation. If you're always under-recovered, always feeling fatigued, experiencing DOMS that lasts 3+ days, it may mean you’re overtraining. You may have an imbalanced equation of expectations to reality.

Recovery Check List:

Are you consuming an adequate amount of calories/protein/micronutrients?

Are you getting sufficient sleep quality/quantity?⁣

Are your training sessions progressing?

Are you giving yourself enough time to recover between sessions?

Are you managing your stress appropriately?

And the most important one… Are you having fun? :)

The answers to these questions will give you insight into your recovery and what adjustments you should be making.

See you in the iron chapel bruh...⁣ 🤙🏽

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