
The SAID Principle & Mobility Training
The gains you make are directly related to the things you do. Your body gets better at whatever you do. We use this idea to guide our training, so we can stimulate changes in our bodies that we want.
You want to get strong? Lift heavy.
You want to grow muscle? Challenge the muscle close to its limit (failure).
You want to be flexible? Spend time at your end ranges with load in a lengthened position (stretch).
When you think of it this way, exercise seems very simple. But for some reason in the land of mobility & rehab, this principle gets completely lost in application.
What is the SAID principle?
It’s one of the main principles of training. It stands for Specific Adaptations to Imposed Demands. In regular-people-speak, this means the adaptations (or the changes our bodies make) are specific to the stressors they experience.
This happens as a protective mechanism. If something is stressful or hard for our body, its response is to make changes after being exposed to the stressful/hard thing, so that it can be better prepared when encountering it in the future.
It’s why you get stronger with lifting weights and faster with running. It’s why your muscles grow as you challenge them with more weights and reps.
Your body wants to be better at the challenging things it experiences, so you can survive.
Sounds simple enough, right?
So what gives?
In fitness, we know that the effects of high intensity exercise are not the exact same as aerobic training (long duration, low intensity exercise).
And that the changes in our body from doing a squat are different from what we can expect from a calf raise.
We know the changes we want in our body dictate our exercise choices. But, when it comes to rehab or mobility, this science & logic gets completely tossed out the window!
There is a huge mismatch between what is actually needed or wanted for the results you seek and what you may have been told or learned will get you those results.
A lot of this is due to a lack of critical thinking. We pass on exercises and memorize “solutions” and “protocols” instead of principles and ideas. It sometimes feels like logic completely gets thrown out the window.
This looks like:
Only doing planks and anti-movement exercises to rehab a low back injury, with a goal of returning to deadlifts (which will involve your spine moving under load no matter how great of a mover you are). Not to mention, at some point your spine will need more load than just planks as your body gets stronger; there is a large gap between the load a plank provides and the loads needed to make your back strong enough for a deadlift.
OR
Stretching your hamstrings because they feel tight, without checking to see if they are actually limited in their range of motion.
OR
Doing I’s, Y’s, and T’s with 5# dumbbells when you are actually limited in shoulder flexion mobility without any added weight.
These are just a few of many examples. The logic is missing. The “What am I trying to accomplish exactly?” and “What adaptations am I working towards with this exercise?” and the “What adapatation do I need to accomplish these goals?” has been skipped entirely…
So what’s the antidote?
You guessed it. The SAID principle.
This can be done using the simple question below when deciding what exercises you should be doing for your goals:
“What changes do I want my body to make?”
Not only will this guide which exercise is best for your goal(s), it will also help you narrow down the other criteria as well – the intensity (how hard/heavy), frequency (how often), duration (for how long), etc.
The more specific your goal, the more intentional you’ll need to be with your programming.
How Specific Do I Need To Get?
It’s a spectrum, of course, and it depends on the end goal (what you want your body to be able to do or what outcome you’re chasing) and what your body lacks or needs improvements in to achieve said goal (your limitations).

The more specific you get, the less wiggle room for your parameters to make sure that particular adaptation is getting stimulated.
This process helps you funnel your options down and direct your focus to the exact changes you want in your body.
If your goal is to just get active so you can ward off chronic disease, almost any exercise can help you achieve that.
But as you move away from general goals and get more specific with the things you want or need (like stronger quads or better hip mobility), there are less options of things you can do to get those results. This is how using the SAID principle to guide your goals helps you funnel down to the exercises and the times and sets and reps you end up with.

Just like in traditional fitness, sometimes we need to build a baseline foundation to start.
…but the longer we are involved in fitness, the more interested we become in wanting specific results.
It’s then that you have to get more specific and intentional with your HOW. Or, you have to adjust your expectations that you may not get the results you are hoping for & make peace with it.
You can’t wave a magic wand and expect your body to produce something without any instructions or guidance. Your exercises & programming are the instruction manual. Make sure your expectations match the manual you are sending to your body.
Understanding these principles >> mindlessly following someone else’s recommendations forever & always.
You might not be a movement professional, but I believe you’re smart enough to understand the principles and the why behind the exercises you are doing. And I think you deserve better than being given a handout of the same 5 low back exercises that everyone else gets regardless of their goals or current limitations, or “prehab” banded shoulder drills that you need to repeat exactly the same way for the rest of your life, or just randomly doing exercises you see on a social media post that promise to fix your hip pinch without any context or explanation.
To learn more about setting a mobility-focused goal, check out my free masterclass called Kickstart Your Mobility Training!
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Hi, I'm Dr. Jen Hosler.
I’m a bookworm, science nerd, and coach of all things movement (physical therapist and strength & mobility coach). You can catch me sleeping in & having a slow morning, doing CARs & lifting heavy things, or sipping a glass of wine on my time off.
Through a blend of strength & mobility training, I’ll help you master your movement & build a more resilient body that won’t hold you back from all the activities you love doing.
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