Three-Factor Model of Adaptation (3F)

Three-Factor Model of Fatigue (3F)
by Mladen Jovanovic

Before I even start, check this article!

Discussing on CNS Fatigue thread, I got the idea to create Three-Factor Model of Adaptation — 3F. Here is the basic premise:

Preparedness = Fitness + Fatigue + Facilitation

Fitness, fatigue and facilitation are “immediate” and specific effects of a training stimuli.

Fitness is level of particualar trait/ability. It is the most “inertial” factor… slowly raise, slowly falls (compared to other two)… Fitness increase spents C.A.R. (Current adaptation Reserve) — or some form of "adaptation energy "— which should be “reffiled” from bigger “buffers” during unloading phases. This is one of mine premise for wave-like loading and unloading principles. Others are: fatigue accumulation, synchronizations of the traits, rest, general/specific ratios etc… Fitness increase is limited by Upper Genetic Limit and Genetic Adaptation Reserve (which can be spend prematurelly by non-continuous training, stress etc, before even reaching Upper Genetic Limit)

Fatigue is (according to my undestanding) an „expression“ (and sensation as RPE, tiredness etc) of control mechanism which limit performance to protect the body from damage or death. It can have various forms and various properties like delayed phenomena in HI CNS fatigue. Fatigue is also specific as fitness is. Fatigue have allways negative sign (contrary to Fitness)… Fatigue is related to Fitness — as athlete advances he need more stress to produce only small increase in Fitness, but it increase great amount of Fatigue.

Facilitation is the the shortest effect of training load. It is also called PTP — Post Tetanic Potentiation, but it may be also due arousal, stimulants, etc. Higher Facilitation can cause higher levels of fatigue afterwards due higher system taxing. It can also have positive effects on performance as negatives — depends on the level of it.

All three of mentioned factors are conceptuall and interconnected!

Speed of adaptation/improvement depends on the “dose-response”, or the ammount of work/load needed to increase fitness (and the level of that increase), but also of the fatigue created by the same ammount of load and the time of recovery (recoverability)! Thus, for best resutls (at the current point in athlete’s career) the one should find the optimal workload to produce optimal adaptation but to also allow the recovery from the same!!! Thus you should use the minimal load to provide adaptation and fast recovery. If you use larger loads, the fitness will increase more, but it will take more time for Fatigue to decline, and thus effects will be less. One should search for optimal loading protocols for a given athlete at a given point in athlete’s career. Note that relations are non-linear!

3F Model can explain all the “modern phenomena” in training better than 2F and 1F models, like: delayed fatigue, fatigue accumulation, facilitation, need for unloading, etc. Due interactions of Fitness, Fatigue, Facilitation and presented „energy adapation drain“, it can be pretty simple to understand the superiority of Conjugate Sequence System and the fight of various traits (e.g. strenght and speed) for same adaptation energy!

Hi Duxx,

What about motivation of the athlete on any given day? Would that be a fourth factor?
Mentally tough and weak athletes can ‘throw the old monkey wrench’ into theory?

the only problem that i have with a more complex model is that a model is meant to be a scaled down version that accuretly describes what occurs in reality. to my knowldege this can be done with a single factor model. ofcourse the 2 and 3 model is more accurate but what advantage or rather how do they better allow us to form a training system off of them. we could come up with a 5, 8, 20, 57 factor model because the complexity of the human system and its adaptation response but how would it add to our functional knowledge of training.

That would be under facilitation stuff!

You are right, but 1 and 2 models cannot explain the faciliation, CSS in more detail, etc… Sure, there would be a lot of more factors to add, but they could be putted into mentioned three groups… like in above example!

i guess im asking how do you apply this to setting up training for an athlete. does it have any beenfit other than being a purely academic pursuit?

It can explain some thing/phenomena, like

  • Continuity of training as a must (if you start/stop, then you will spend more gas — adaptation energy – like two cars, one going trought city (traffic, red/green lights, etc) and one going on a open road. After 100km traveled, the second car will spend less fuel, or will travel futher with same gass tank)
  • Unloading phenomena explained at various cycles (mezo, makro, yearly, olympic etc)
  • Fatigue accumulation
  • Facilitation
  • Conjugate sequence system (developing same traits at the same time that fight for the same resource — CNS for example – will not be optimall, because both will drain same adaptation reserve)

Anyway, I created this approach to explain myself the phenomenas mentioned… If can someone find it usefull — great — if not, then… well… give me a bad rep! :slight_smile:

That’s compelling…

It is kind of interesting that if you look at all the the “systems” that have been successful for years and been put through lots of scrutiny they all have a few things in common. I think that that is what most people are missing. They are always looking for the next program with the secret link. The secret is that they should find the few things that all of the “great” programs/systems have in common and stick with and/or build on that. The human organism hasn’t evolved that much since the discovery of sports science. What worked back then will still work today. We need to not drop the basics that have always worked for the new stuff but instead keep those basics and just add to them to complament them or to enhance them.

That is all, my rant is over.


Tim… I am NOT “inventing” new methods here… I am trying to explain old ones better!
Thanks for your rant :slight_smile:

Duxx, excellent job as usual. This definately makes more sense than the 1 or 2 factor models. If only we had a good way to measure the 3rd factor with low error…

Be careful, a lot of very useful things started as “purely academic pursuits”.

im not knocking the pursuit im jusst wondering how it is applicable. over complicated models can cause trouble as a model is meant to be something that is simple and yet still accuretly describes a phenomenon.

No, no, no Duxx. I think I didn’t type that well. What I meant was that I like what you are doing. You are taking what has already been proven and building on top of it. This I like. I’m sorry if that came off wrong.

What I was getting at is that I know you have been exploring the old Starr/Pendlay workout. I myself love that set up. There have been so many people, both begginer and advanced, that have made great gains off that work out yet for some reason all these yodas want to either write it off cause it’s old or change it in some crazy fasion. This kills me.

You are not doing that. You see that it is good and that it works and now you are trying to build beyond that. No complaints here. I believe that more people should use your approach!

Sorry for the misunderstanding,

Thanks Quark! Three factors are hardly measure independandtly — we can measure only their overall effect —> PERFORMANCE! — and make statements/conclusions about fitness, fatigue and facilitation levels at a given moment.


I am currently at the program (Intermediate Version), and I am not stuck yet… still increasing weights for 5kg (10lbs). I started lower, now it is 3rd week of it…
I had some problems during the last year because my gym only have 5KG Olympic plates, so the minimal increase in weight is 10kg (22lbs), which is too much… Now I found a solution: tie a small plate (non-olympic) with a rope! It look funny, but hey, its working :slight_smile:

You mean on Modified 5x5 Programm I have posted? That is a kid’s play… I was playing variables and resoning… 5x5 method gave me some good ideas…
Yet, I am still confused about the infos out-there, like switch exercises often and stuff…
Just reading “Starting Strenght” — arrived two days ago. Great stuff… but I have some issues with their squat method — low bar position! Wouldn’t that decrease back stress but increase shoulder problems, compared to high bar position?

Yes and yes. But the advantage is the greater weight that you are able to use and you also have to bend foward less. I suppose maybe they like they idea of that for begginers. It is both motivating and less likely to cause back problems.

It does, like you say, create some shoulder issues. But I wonder if since the book deals primarily with “begginers” i.e. smaller guys they aren’t as worried about shoulder flexibilty. I am only guessing here though. Your concerns are well warrented.

thanks! I will keep reading… and maybe post some things on Quikazhell’s thread (Starting Strength)!