The SAID principle stands for: Specific Adaptations to Imposed Demands. Or simply, the type of training you do determines how your body responds and adapts. This means that the training you do needs to be focused on a set adaptation – determine what adaptation you want to see, train in accordance for a period of time and see the adaptation occur. The SAID principle works for all types of training, from strength and power to hypertrophy to aerobic endurance. That is why having a clear plan and goal is key to making gains in your training.
Now that we know that the body responds only to the stresses placed upon it, the key is to figure out how to use this to our advantage as we continue on our fitness journey.
So, let’s break down the SAID principle further, including some examples of where you can apply SAID principle to your training
SAID Principle Explained
Specificity of muscular adaptation to exercise
The way that the body responds to stress is pretty simple but brilliant.
We place stress on the body, by lifting weights for instance, which is difficult for the muscles used so the body makes the muscles stronger. And voila, we can handle the stress better next time.
Let’s use the dumbbell biceps curl as an example.
Let’s say you did 3 sets of 10 biceps curls with 20lb dumbbells and this is a hard workout for you.
Because you used a challenging weight during the biceps curl, and it was difficult there was a lot of stress placed on the individual muscle fibers that had to contract to move the weight up and down. This stress caused damage to the muscle fibers within the biceps muscle (and synergist muscles).
The body responds to the damaged muscle fibers and sets off a series of responses to rebuild the muscle fibers in the biceps a bit stronger than they were before. This is the theory of super-compensation following stress and is why proper recovery is key between lifts.
Sometimes this muscle damage can cause muscle soreness after working out, which is called DOMS. To learn more about DOMS check out my article on it – Why Muscles Get Sore After Working Out.
The newly adapted muscle fibers in the biceps are now bigger/stronger than before the workout. This means that in your next workout, if you did another 3 sets of 10 biceps curls with 20lb dumbbells the workout would be easier than the first time.
It turns out exercise order affects the body’s adaptation too! The body responds best to exercises done early in training sessions. So for max gains, you should put your most important lifts at the start of your workouts.
This is the main key to the specificity of adaptation – your body is stressed and responds by building itself stronger.
But we only see adaptations in the muscles worked. There are only specific adaptations based on the imposed demands.
When we perform biceps curls, we see changes in the strength and size of our biceps – but there is no change in our calves. This makes sense, we only see changes in the muscles we work out.
Specificity of the nervous system's adaptation to exercise
Now that we have covered the specificity of muscular adaptations, it is important to consider how the nervous system adapts to the demands placed on it.
You may have heard people in the fitness community talk about ‘greasing the groove’ in an exercise. This is basically the phenomenon where you get better at a movement by doing it more often – which makes sense. If you want to be good at something, you need to do it and practice it (like the 10,000-hour rule but toned down a lot).
This concept also plays into the SAID principle, where our nervous system adapts to the demands placed on it.
This starts to dive into the topic of motor learning a bit, which is not in my wheelhouse and if you or I truly wanted to understand it we would have to do a Ph.D. in the field/read hundreds of articles/textbooks.
Basically though, our nervous systems respond to the demands placed on it (i.e. learning a new movement) but creating motor pathways that guide our movement. Early in the learning process, these pathways aren’t very dialed in or efficient, which is why someone learning a new movement looks shaky and not smooth.
As we practice movements more and more, our movement skill increases. There may still be some reps that look like trash, but there is an overall trend toward better movement ability and efficiency.
The more and more we practice skills, the more efficient and ingrained they become. At a certain point, the movement becomes second nature and we don’t even need to really think about what we are doing anymore.
This phenomenon is why you can take someone that has never back squatted before and increase the load they can lift quickly (newbie gains). Someone can go from never back squatting before to being able to squat over their bodyweight, simply by increasing their nervous system efficiency with the movement. They didn’t necessarily “get stronger” but got better at the movement and thus can move more weight.
But again, there is specificity to this. If you practice back squatting technique, you will get a better back squatting technique. But you probably won’t be much efficient at your power clean technique.
Read more: How often, how intense and how much you should train to maximize strength gains
What are imposed demands in SAID principle
We know that we only see adaptations in the muscles, movements or energy systems that are stressed, but what does the “imposed demands” of the SAID principle mean?
Really, this just means that your sets, reps, volume, intensity, etc. should be in alignment with what you are trying to achieve. Depending on what these parameters are, the body will respond differently.
Over the course of training history, scientists (both professional and amateur) have developed training guidelines that correspond to certain adaptations. Essentially, the imposed demands change depending on what adaptations you want to see.
For instance, if you want to see muscle hypertrophy you need to perform more volume at a lower intensity (3-6 sets of 8-12 repetitions for multiple exercises per muscle group).
If you want to increase strength, then you should consider 2-6 sets of 6 repetitions or less.
In addition, we know that the body super-compensates after it is stressed – which is why we see muscle growth/strength gains/increased speed/etc. Therefore, as our training progresses, we need to increase the demands placed on the body so that the stress is enough to elicit an adaptation.
If you want to learn more about sets and reps to achieve your training goals, check out my article detailing everything about sets and reps.
How to know what stresses to put on the body
The stresses placed on the body should be in agreement with the goals of the training cycle or period.
For instance, if you are looking to increase muscle mass and are in a hypertrophy training block you should be performing higher volume (more sets and reps) at a lower volume than if you are trying to improve your maximum strength numbers.
Again, this is why having goals for your training is key.
However, there is a Goldilocks effect when it comes to the stresses or imposed demands put on the body. Not only do the imposed demands have to align with your goals, but you can’t have too much or too little stress.
If there is not enough stress then there is no adaptation, but if there is too much stress then you run the risk of injury, illness and/or overtraining.
Thomas Kurz states that “for consistently good results, training loads should be such that an athlete makes progress while not leaving the state of good health.”
Therefore, workouts should be hard enough where your body has to super-compensate and thus you see the adaptations you are looking for (i.e. strength increasing, running speed increasing, bodyweight decreasing) but not so much that you are chronically overtired, sick, or dreading working out. You might need a deload week if you find yourself sick, tired, or worn out.
When you are working out hard, you might find yourself struggling through a specific part of the lift. Hitting sticking points in lifts can be super frustrating. If you want to learn more about why sticking points happen and a bit of science on the topic check out my article on sticking points here.
It all starts with a goal
The key to using the SAID principle to our advantage is to know what we are looking to get out of our training. This is where having training goals will drastically change the way our training looks.
If you are trying to compete in powerlifting, your training will (or should) look a lot different than someone that competes in triathlon and that makes sense. The sports are totally different and place different stresses on the body, so you should train differently for the two.
That is exactly what the SAID principle is all about – the type of training and movements you do will change the way your body adapts.
I’m currently learning how to write computer code, and one of my colleagues continually reminds me that the best thing about code is that it does what you tell it to do, and the worst thing about code is that it does what you tell it to do.
The body is the same: the best thing about training adaptations is that the body responds to the stresses placed on it – but if the stresses you place on the body are not in alignment with your goals, then your adaptations won’t get you towards your goal either.
This is why when you start your training block/period you should write down your goals, even if they are generic
- Do you want to gain size?
- Are you looking to get stronger? In just one lift, or the big 3 lifts?
- Do you want to be better conditioned for your pick-up hockey games?
- Is your main focus jumping higher to be able to dominate your volleyball league?
The goal you are looking to accomplish or the gap you are trying to close is what drives your training parameters and sets the stage for the demands that you will place on your body.
Read more: 9 scientifically-backed tips to help you maximize your strength training
Cross over effect of training
Sure, all of the above sounds good but you might be thinking: “if I run, it surely will improve my aerobic conditioning and there would be some carry over to cycling ability.” And that is 100% right.
If you focus on a specific exercise or training modality (aerobic training) then it will show some cross over effect on other exercises or training modalities.
However, the principle of SAID is really focused around specificity. So, while you will probably see improvements in cycling endurance if you spend a lot of time working on running endurance, the gains won’t be as big as if you simply worked on endurance cycling.
The morphological and functional changes caused by exercising specifically prepare the athlete for the same type of exercises that cause these changes
– Thomas Kurz
From a strength and power perspective, you may want to think about using the example of squatting and jumping.
If you focus on increasing your strength in the back squat, you will probably also see gains in the height that you can jump. But, if for instance, you switched from regular back squats to barbell jump squats the carryover might be greater.
And that brings us back to the fact we always see Specific Adaptations to Imposed Demands. If you want to get good at X, you need to practice X.
Summary
In conclusion, the SAID principle really goes hand in hand with the KISS (keep it simple, stupid) principle.
If you want to get good at something, you should do that thing. And not only should you do it often, but you should also gradually increase the volume/load/intensity so that it continues to be pretty difficult and you see yourself move towards your goal.
Then after you reach your goal, you should find something else to focus the majority of your attention on, while continuing to maintain some work in other areas too.
If you do this consistently over a number of years, you will see incredible progress.