Human movement/performance is a summation of many different sciences. In order to optimize training we need to understand how these sciences are intertwined. The best way to illustrate this idea is by looking at post activation potentiation (PAP) and how the acute changes in physiology will affect the physics of movement.
PAP is the process of bringing the body to its highest functioning state. Typically, post activation potentiation is done by using some sort of maximal intent movement, over a short range of motion, to facilitate the performance of another movement.
Two window model of PAP (Image 1)
For example, you might see someone use a partial high box squat (~90%+ 1rm) to facilitate the performance of a vertical jump.
SUPRA-MAXIMAL FRONT RACK HOLD (Image 2)
What Is Happening During Post Activation Potentiation?
There are several possible physiological mechanisms that are occurring during PAP.
Mechanisms
-
Image 4 Increase in calcium sensitivity (1)
- Increase in neural output(1)
- Increase in local temperature (2)
- Increase in local enzymatic activity(3)
- Increase in local blood flow (2)
Just to name a couple…
All of the above possible mechanisms may facilitate the performance of the following movement.
How PAP Changes The Physics
Lets stick with the example of using PAP to facilitate vertical jump height and figure out how the changes in physiology influence the physics of the movement.
If you want to jump higher, we need to increase the impulse of your jump (Click here for details on impulse)
Impulse –> Force (time) = Mass (Velocity final – Velocity initial)
If performing a facilitating PAP exercise leads to an increase in jump height, we know that something had to change in the above equation. What changed? Well, final velocity dictates jump height, so we know the number on the right side of the equation had to increase. So, in order to make up for the increase in the momentum of the movement (right side of the equation is momentum), something on the left side had to change as well (force or time).
What Changed?
Either force, or time force is expressed had to of changed. However, we know the time of movement didn’t increase (jump did not take longer), so time force is expressed remains the same. This leaves us with only one option, force had to change.
The increase in force caused by the physiological mechanisms that occur from a properly executed post activation potentiation exercise led to an increase in velocity of the jump, which is reflected by an increase the jump height.
Conclusion
Changing the physiology will change the physics of the movement and ultimately influence performance. Whether is is fatigue changing the amount of force being expressed, joint positions changing the amount of time being expressed, or some combination of both, the change in physiology will change the physics and visa versa. When we start changing force vectors, we start to change the joint angles and muscles being used (this can be saved for a latter post). In order to understand how the body works, we need to make sure we have a solid understanding of the sciences that make up human movement.
Reference Links:
(1) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3164001/
(2) http://www.mhhe.com/biosci/ap/vander/student/olc/c-reading4.html
(3) http://www.worthington-biochem.com/introbiochem/tempeffects.html
Image Links
- Image 1: https://bretcontreras.files.wordpress.com/2010/04/capture.jpg
- Image 2: https://i.ytimg.com/vi/Lhqh6yECiNQ/maxresdefault.jpg
- Image 3: https://www.t-nation.com/img/photos/07-175-training/image001.jpg
- Image4:https://sites.google.com/a/hsd.k12.or.us/mrphilhiscience/home/physics
- Image 5: http://www.bigblueview.com/2017/2/28/14750034/nfl-scouting-combine-2017-drills-explained-why-they-matter