The posterior chain is the group of muscles on the back side of the body while the anterior chain is the group of muscles that runs up the front of the body. Posterior muscles of the legs include the glute, hamstring and calves while the anterior muscles include the quads and the tibialis. The muscles in the posterior chain are important for many reasons.. The combination of the size and higher ratio of fast twitch fibers in these muscles makes them best to produce explosive, powerful movements. It is generally accepted that when it comes to explosive power, the posterior chain contributes about 60%, the quads about 30% and everything else about 10%.
What is A:P?
The A:P is a simple metric that measures activity of the anterior chain to the posterior chain muscles. It is common to compare anterior posterior by strength, force, or sEMG in facilities with the right equipment, and it can be completed manually. The A:P is presented as a ratio:
A:P = Anterior/Posterior
An A:P of 1 means that the anterior and posterior are equal contributors. However, based on hundreds of training sessions, we have determined that normal anterior to posterior should generally be less than 1 where the Anterior should be contributing less than the posterior for all types of movements including vertical jumps, pitching, shooting, etc, for maximum power.
How to track A:P
The load incurred by specific muscles in the body can be tricky to measure. Coaches and athletes with access to clinical sEMG or strength measurement tools can measure A:P contribution however, most organizations want to better understand what their athletes muscles are doing in real settings. There are very few technologies in the consumer market that can measure this. However, recent advances in sEMG technology by Athos can provide specific information on the load incurred specifically by the anterior and posterior chains. To learn more about how you can track A:P, click here.