Action is almost always faster than Reaction, and your physiology has a lot to do with it, but training helps shorten the gap. (source)
The Nervous System, Reflexes, and Krav Maga – Part 1: Action vs Reaction

This is the first part in another series about connecting the system of Krav Maga to your nervous system and day-to-day life. Specifically your nervous system and your reactions. (See previous series Awareness Colour Code, The Nervous System & Mental Health)

Acting preemptively to anticipate a stimulus, or rather acting faster than the stimulus can affect you, vs Reacting to a stimulus, will give you different results. This is due to the fact that there’s this thing called time. Time is essentially the measurement of particles from one point to another due to the fact that energy has made them move in one direction or another. But don’t worry, this isn’t going to be some theoretical time-space physics lesson as, who am I kidding, like most others I barely understand such things. Instead it will be a breakdown of how Action is almost always faster than Reaction, at least when it comes to us humans, which means it is an important thing to understand in Krav Maga and overall self-defence.

So how does action vs reaction work in us humans? It all starts with electrical signals in our brains, generated by our neurons. Our neurons, brains, conscious, and subconscious minds interpreted some type of data from our various senses (eyesight, hearing, proprioception, etc.) based on whatever stimulus there is in front of us. This could be anything from a knife-wielding maniac to your douche roommate jumping out in the dark to scare you for their newest YouTube video. Regardless of what the stimulus is, if it is a threat to your wellbeing, physical or otherwise, you must interpret the stimulus rapidly to make a correct decision. There are many factors that contribute to how fast you can actually react, but let’s stick to your brain, your body, your training/experience (post 2), and how that combines with some basic natural reactions (covered in post 3 & 4). But to understand it all let’s go back to your brain and those magical little things called neurons and how they work with your body and re-action times.

Your Brain

There are several models to explain this process so you can better understand it and, as always, we can sum them up in acronyms…yay! The two acronyms I will look at are PAFA and ODDA (the famous “ODDA loop”).

PAFA stands for Perceive, Analyze, Formulate, Action. This is the model that I use at UTKM, as it was the first introduced to me for the purpose of self-defence. OODA, on the other hand, stands for Observe, Orient, Decide, Act. They employ different verbs but they are the same steps and mean exactly the same thing. (I’m referencing both in case you encounter one vs the other in your training. It is really a dick-swinging contest as to which is “best.”)

Let’s break this down with simple examples to help you understand the process that is going through your brain before you either Act pre-emptively or Act Re-actively.


  1. Perceive – There is a thing there!
  2. Analyze – What is this thing? Is it going to eat me? Should I run? Should I fight?
  3. Formulate – Come up with a plan for what is the best response, Fight, Flight, or Freeze?
  4. Action – Execute Plan


  1. Observe – There is a thing there!
  2. Orient – What is this thing? Is it going to eat me? Should I run? Should I fight?
  3. Decide – Come up with a plan for what is the best response, Fight, Flight, or Freeze?
  4. Act – Execute Plan

That is what order in which our decision-making process operates and, as a general rule, how fast you can react. While it is slightly different for every person your brain takes about 0.25 seconds to accomplish steps 1-3 and then depending on many factors it can take less than a second or many seconds (too many?) to actually begin to Act.

Before I get into what that actually means for self-defence let’s break down what each stage is a littler further:

  • Stage 1 – Is your senses alerting you. Whether it be sight, sound, that tingly feeling, or voodoo magic that tells you “HEY IDIOT! There is a thing there!” It may be the face of a velociraptor in the long grass, the classic knife-wielding maniac, or that ex who ruined your life. Regardless, at this stage, all you are aware of is that it is a thing, but you are not quite sure what it is or if it is dangerous. As far as you are concerned in this brief window of time, there is simply something there and you really are not quite sure about its meaning or intentions.
  • Stage 2 – Your neurons essentially do a cross-reference of everything it knows of in order to tell you what that thing it is. Now you know for sure if it is Velociraptor, a Knife-wielding maniac, or that ex you never wanted to see again! Regardless of what the thing was you have not fully decided what to do yet, probably because you are quite possibly shocked that it is in fact the ex who ruined your life and you are at least for a moment trying to avoid panic, all while wishing it would be better if it was extinct dinosaur or a knife wielding maniac (in your mind both are preferable).
  • Stage 3 – This is where hopefully you have not actually panicked and your brain and neurons again cross-reference its database to determine the best course of action. The appropriate response for your brain is to activate its fight or flight mechanism, though, with our more modern sapient brains, conversation is technically an option to avoid a drastic fight or flight response. (I mean, seeing that ex is traumatic enough, getting a text from them afterward saying “Hey, I saw you running away! Why were you such a little bitch?!” is just humiliating.) Nonetheless, this step is all about making a decision. You have little time until they see you. You take a breath, realize that Fighting is not appropriate and that conversation is out of the question, so you take a calmer version of flight; you decide to run slowly enough that it won’t draw attention to you.
  • Stage 4 – You execute your clever plan. Luckily there are enough people around to cover your exit as you shuffle away, sneaking behind a corner while keeping a close eye on your nemesis to be sure that they didn’t see you. You watch them walk past and you sigh with relief, reminding yourself to calm your nervous system back down from high-strung Red to a cool Yellow.

Regardless of whether you are on the “defence” or “offence” in any given situation remember that for both persons involved moving from the first stage, identifying the stimulus as a thing worthy of paying attention, to the third stage, making a plan, both parties are going through the same neurological process in about 0.25 second. It’s the 4th stage that can make all of the difference, as humans’ reaction times can vary wildly. If you act sooner in the 4th stage than your perceived threat, that threat may not even have gathered enough information to actually act on any plans to harm you. Remember the saying “the hand is quicker than the eye” and that is because processing visual data can be quite taxing for the brain. So much so that your brain often fills in the blanks in the form of an educated guess based on previous data and experience. This is actually a big part of the reason eyewitness accounts are so unreliable.

Now that you have a basic idea of what your brain is doing let’s connect it to the body.

Your Body

There are many factors that can affect how fast you go from stage 3 to 4, including genetics, experience, training, and, of course, the state of your body. Once your brain has decided what to do it needs to send electrical signals to your muscles and get you to start acting. This is assuming you haven’t gone code Black and cannot act, instead freezing in place, or worse, passing out. Regardless of what you decided to do, if you are running or fighting your body should be in code Red, which required the activation of various body parts and systems to do specific things to enhance your reaction. Let’s just keep it simple to a few things; your eyes, lungs, and muscles. More detailed biological specifics can be found here, or in our basic breakdown of Fight, Flight or Freeze.


Whether it is because of an adrenaline surge from the fight or flight mechanism, pharmaceuticals you are on (prescribed or otherwise), or “street drugs” someone is partaking in, there are many factors that can affect whether your pupils are dilated or constricted, to let more or less light in. Depending on how much light is coming into your eyes or whether or not a drug is changing how fast your brain can process the visual stimulus it will affect how fast you can move from stage 1 into stage 4. If it is due to an adrenaline rush, your eyes should dilate allowing more light in to allow a clearer and, hypothetically, quicker response to your visual information. Contrast that with certain drugs that may cause the constricting of the pupil, which will allow less light and, hypothetically, a slower response time due to a block of information that is less clear than you would like. There is also a natural skill component, as some people are able to process visual cues faster than others which will, in turn, affect how the rest of your body reacts to a perceived threat. Keep in mind that if you can’t see a threat at all you won’t even know there’s a problem and your body won’t kick into action as it’s supposed to. If this is the case you better be hoping the threat is your ex and not a velociraptor.


Assuming there is nothing seriously wrong with your lungs, if the fight or flight mechanism is kicking in it should be relaxing your airways so that you can be more efficient in your breathing. This is of course assuming you are in reasonable enough shape to be able to breathe effectively when under duress. If you have breathing problems, asthma for example, then if you are forced to breathe fast enough, especially underdress, this can increase your stress levels to the point where breathing is so difficult your body starts to panic and potentially send you into code Black. Again, assuming you have no issues, the stronger (in better shape) your cardio vascular system is, the longer you will be able to sustain the increased activity required to deal with the threat. Additionally, if your adrenaline rush requires you to push past more than 30 seconds you may face a hard adrenaline dump. This means all the speed you had temporarily is now gone and everything is more laboured. If your cardiovascular system is strong it will allow you to compensate for this dump, allowing you to keep a reasonable response time. Of course if you smoke, or are just completely out of shape or obese, then along with the adrenaline dump your lungs will already be working overtime, most likely causing your response time to fall to a less-than-effective response. This means that you can no longer run from that knife wielding maniac and will be forced to fight, which is now considerably more difficult for several reasons. Of course, if it is that ex discussed earlier, then unfortunately you are going to have to talk to them while super out of breath and this time it isn’t because “they took your breath away.”


There are a couple of factors governing how muscles can increase your reaction speed. The most obvious is, once again, tied to the fight or flight mechanism, as the rush of endorphins, including adrenaline, speed up your muscle reaction time, as well as potentially increasing strength. This gives you faster reaction times overall… at least until the dump happens. This time frame from the stimulus, to stage 4 is very short. Though it may vary from person to person it could be a matter of seconds to minutes until you crash into the dump, which inevitably slows down your muscles. This is a big part of the reason pure self-defence is meant to be 10-30 seconds of FIGHT so that the threat is done or you are clear of it prior to the dump, which is when combative training in a traditional sense of “fighting” is then needed.

Another factor which can affect the reaction speed is Fast Twitch vs Slow Twitch muscles, or type 1 and type 2. Though you can train your muscles to have faster reaction times there is a genetic component which often means some people have more of one type of muscle than the other. Fast twitch muscles are associated with explosive energy or quick energy use, which translates into faster reaction times. If you are naturally gifted you will inevitably be faster, developing quicker response times regardless of your training. This is really the luck of the draw and is why some people excel in certain sports over others. With regard to sprinting (quickly getting away) or explosive punches and tackles, fast twitch muscles are an asset. Combine more fast twitch muscles with a strong cardio vascular system and you will find it far easier to quickly make a decisions and execute stage 4 (of either model). For the rest of us, who have mostly slow twitch muscles (including myself), we have to compensate with extensive training and a higher skill floor.

What this all means

As the last sentence suggests, a large percentage of humanity has more slow twitch muscles, which are better for endurance or longer tasks. Which means we must make up for our lack of fast twitch muscles and natural athletic ability with training. This challenge will be covered in the next post.

For now you have to get your head around your reality. Do you know what kind of reaction times you have? If not, you can always find out, as there are many products and games on the market that can let you test your reaction times. Of course, remember that training for a specific task will increase your reaction time for that specific task and not necessarily every task.

Something you do need to know however is how do your mind and body react to threats? Do you always choose flight? Or is it always a fight? Success in self-defence means you are actually able to do both and make decisions as consciously as you can, based on more than the primal response to stimulus. Though this is of course more complicated than presented here, but for now it’s a good start.

Written by Jonathan Fader.

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