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S.A.I.D. Principle and Adaptation Energy

This principle applies to every corner of fitness and can be used to as a guiding tool no matter what you are trying to achieve. SAID stands for specific adaptions to imposed demands. The SAID principle simply states that your body will adapt very specifically to the demands you place on it. Adaptation energy is the energy required for your body to adapt. This adaptation energy is essentially your ceiling, how much can you adapt in a day or workout, or even during a workout cycle. The two of these theories, SAID principle and adaptation energy, can be essential in all workout programs, no matter the goal.

SAID Principle

What specific adaptations does your workout program need to give you? If you are an endurance athlete, you obviously need better endurance. But one adaptation that is extremely specific is mitochondrial density. The mitochondria are where the magic happens for endurance athletes, it is the location where fat is burned for fuel. When you have more mitochondria, you are creating more energy for your competition. If you are a power athlete or field athlete, you obviously want to create as much power as possible. One specific way to increase the power you create is tendon stiffness. The stiffer the tendon, the more power you can exert into the ground.

If you are disregarding this principle, you may not be training specifically enough to succeed.

Adaptation Energy

How hard can you workout and recover to get the most out of it? This one is especially important when it comes to working out multiple times a day, or when a strength athlete is also training cardio. Strength training and cardio use 2 vastly different energy systems, and to adapt to your highest potential, its best to have a set priority. If your main goal is strength, you want your cardio as far away (in terms of time between workouts) from your strength training session as possible. If you do one hour of strength training and one hour of cardio back-to-back, you will not get prime adaptation out of both sessions. Let us say your adaption energy is on a scale of 1-10, with 10 being the best change and 1 being the worst. Your cardio change would be a 5 and your strength will be a 5. Both sessions may yield results, but not optimally. However, if you train strength 4 days a week, cardio 2 days a week, and rest 1 day, your strength days will be closer to 10 in terms of strength change, and your cardio will be closer to 10 in cardio change.


Because of the way the body adapts, our training needs to be based on a specific goal and built towards accomplishing the intricate steps to achieve that goal, training a broad spectrum will not lead to great results in any one facet of performance.

Due to the limited amount of adaptation energy our body has each day, careful consideration needs to be taken when looking at our training and what is going to lead to the most important change. This also plays a role in exercise timing, so that our body does not get confused as to what our main goal is that we need to accomplish.

Chris Still

BS Exercise Science


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