Understanding Principle of Specificity (the SAID principle)

Principle of Specificity or the SAID principle (Specific Adaptation to Imposed Demands) as commonly referred, states that training will yield specific adaptations to imposed demands. The principle of specificity doesn’t really explain what’s actually happening physiologically to create those adaptations. This guide will help foster an  understanding of the specificity of transfer from strength training facility to the adaptations experienced by athletes.

By Travis Mash

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Contraction Mode (concentric, eccentric, isometric)

There are three primary modes of muscular contraction. Shortening of a muscle is called the concentric contraction. You can think about performing a biceps curl drawing the lower arm closer to the upper arm creating that famous lump on one’s arm. Lengthening of a muscle is called the eccentric muscular contraction also referred to as the negative. Here you can think about the lowering portion of a back squat where the quadriceps are being lengthened. Finally, force production without a change in muscle length is called an isometric contraction. You can think about pausing in the bottom of a back squat.

Contraction Modes diagram

Simply put, when an athlete performs a lot of concentric contractions, they get better at producing force with concentric contractions. When an athlete focuses on eccentric contractions, they get better at producing force eccentrically. The same goes for isometric contractions. However, if I simply tell you this part of the story, there’s a lot left out of the picture, mainly the ‘why’. 

Focusing on each contraction creates various adaptations specific to the contraction mode. Therefore, depending on the adaptation needed for the specific athlete in his or her specific sport, it’s beneficial to focus on the specific muscular contraction that will yield those adaptations. 

Here’s a look at those various contraction modes along with the specific adaptations of each (click below to learn more):

Concentric Muscular Contractions

 Eccentric Muscular Contractions

Isometric Muscular Contractions

Range of Motion

An athlete will get stronger in the range of motion that they load during strength training. Therefore, one could conclude that an athlete should only train within the range of motion required by their sport. As always, it depends. When it comes to strengthening an athlete for their sport, 100% a coach should focus on stabilizing the athlete in the range of motion required by the athlete. However, there are other adaptations that are important for overall health and performance throughout a full range of motion.

In summary, a full range of motion should always be a target, but there is a time and place for partial aka specific ranges of motion. Check out the full range of motion guide.

Muscle Group and Fiber Type

Probably the most obvious adaptation is that the muscle group being worked will get bigger and stronger than the ones not being worked. However, there is a bit more to it. Understanding skeletal muscle hypertrophy is a major importance for any athletic performance coach.

Yes, you can add muscle mass with very little intensity (weight on the barbell) with lots of reps similar to the muscle mass added with moderate to heavy loads for less repetitions. However, each method stimulates many different adaptations. 

If you’d like to learn more, check out: Muscle Hypertrophy: From Theory to Application

Muscle hypertrophy

Strength Endurance Continuum

When it comes to the actual load that an athlete can put on the bar, there are only a few options. You can go light to moderate loads for lots of repetitions, or heavy loads for fewer repetitions. Of course, you could lift lighter weights as fast as possible for fewer repetitions with an emphasis on barbell maximum velocity. All three of these potential choices will yield different adaptations. 

Here’s a basic breakdown:

  • Low to moderate weights for higher repetitions will yield hypertrophy with a lean towards muscular endurance.
  • Heavy weights for lower repetitions will yield hypertrophy with a lean towards absolute strength.
  • Low to moderate weights for lower repetitions with a focus on maximum velocity will yield improvements in speed.

To explore this further, check out:  Repetition Velocity: The Adaptation is in the Speed.

External Resistance

When it comes to external resistance, there aren’t that many choices. Unless you are using machines, there are only free weights in the form of metal or rubber bumper plates, or most recently, bands and chains made popular by Coach Louie Simmons’ Westside Barbell Club. 

Which should an athlete use? Well, as always,  it depends. To learn more, check out: Bands and Chains and the Potential Adaptations

Bands chains and adaptations

Velocity of the Repetitions

I mentioned this  in the section on the strength endurance continuum, however, here I am mainly referring to fast versus slow repetitions. When an athlete exerts maximum intent on a barbell, the maximum number of high threshold motor units are also called on in the neuromuscular system. Understanding true compensatory acceleration training is crucial for maximizing the athletic adaptations possible for each athlete. 

Check out our Compensatory Acceleration Training Guide here.

Sometimes coaches will still have their athletes purposely lift the barbell with a slower tempo. There are some positive adaptations from this method, but not as many as other coaches might believe. Therefore, it’s important to understand the truth behind what some coaches call time under tension training. Check out: Time Under Tension, Effective or a Myth?

Principle of specificity - time under tension

Force of Contraction and the Rate of Development

Strength will always transfer in quantity and rate meaning the athlete needs to exert amounts of force equal in total amount and at the same relative rate as the athletic endeavour the athlete is training for. If you are a quarterback, it’s not that important to deadlift 275kg/605lb at 0.3m/s. Whereas, if you are a linebacker, performing cleans at 1.0m/s and back squats at .7m/s is incredibly important. 

To understand the process of force production, I recommend starting with: The Size Principle

And, if you want to understand the rate of force production, check out: Rate of Force Production

Fatigue Specific

Of all the latest science that has positively affected athletics, fatigue management seems to be really helping teams and individuals succeed. Decades ago when I played football, it was common for coaches to run athletes into the ground. Now coaches are trying to match the amounts of fatigue that athletes will actually experience in the game. 

Remember if you coach athletes to perform while fatigued, their expression of speed on the field will follow suit meaning they will learn to survive. Here’s an article of assessing daily readiness and fatigue: Assessing Daily Readiness and Fatigue

Energy System

There are three main systems the body uses to produce energy. For the first 10-seconds, the body uses the phosphocreatine system. After the 10 seconds, the primary system becomes glycolysis lasting to around the first two minutes of exertion. After that, the aerobic system takes over with the oxidation of carbohydrates and fat.

The energy system used in practice will be the energy system that will be stimulated to adapt. Of course, if you are overtraining athletes, the adaptation will be a negative one. Dr. Andy Galpin brakes it down for us in this video:

Force Vector

Force production has a direction, and improvements will depend on how force is applied during training. It can be generated vertically, horizontally, laterally, and rotationally. Enhancing vertical and horizontal force can boost an athlete’s rotational capabilities, but targeted training in a specific direction is essential to maximize performance in that area.

Chris Beardsley’s article is a great resource to learn more: How do force vectors affect the type of strength we develop?

Conclusion

As coaches, we want to make our athletes stronger, faster, more explosive than the other team. The principle of specificity is a blueprint for how to create those specific adaptations. To sum up, we learned that there is a specific transfer of training in the following stimuli: 

  • Contraction mode
  • Range of motion
  • Muscle group being trained
  • Point of strength endurance continuum
  • External resistance 
  • Velocity
  • The amount of force and the rate of the force development
  • Fatigue
  • Energy System
  • And the force vector

I explained that there is more to it than understanding that there is a specific adaptation to the imposed demand. There are physiological adaptations that create changes in the performance of athletes. I hope this article is a source of information for the many coaches and athletes out there trying to understand the world of sport science. This article alone provides the information necessary to develop a solid foundation of athletic performance. There’s a lot to discern, but having everything in one place regarding specificity of transfer will help coaches group them all together for present and future decisions regarding the performance of their athletes.

References

  1. Suchomel TJ, McKeever SM, Comfort P. Training With Weightlifting Derivatives: The Effects of Force and Velocity Overload Stimuli. J Strength Cond Res. 2020 Jul;34(7):1808-1818. doi: 10.1519/JSC.0000000000003639. PMID: 32398635.
  2. Taylor, J. L., Amann, M., Duchateau, J., Meeusen, R., & Rice, C. L. (2016). Neural Contributions to Muscle Fatigue: From the Brain to the Muscle and Back Again. Medicine and science in sports and exercise, 48(11), 2294–2306. https://doi.org/10.1249/MSS.0000000000000923
  3. Lavallée, L., & Flint, F. (1996). The relationship of stress, competitive anxiety, mood state, and social support to athletic injury. Journal of athletic training, 31(4), 296–299.
Coach Travis Mash

Travis Mash

Being a World Champion in powerlifting, Travis competed at a world-class level in Olympic weightlifting and has coached professional Olympic weightlifters alongside Don McCauley and Glenn Pendlay at Team MDUSA. Now Travis coaches the most successful weightlifting team in the USA.