PEC (bilateral Posterior External Chain)

PEC (Posterior Exterior Chain) is another term used in Postural Restoration Institute®. This chain of muscles are to be exterior (outside) global musculature and tighten or lock your body.

Muscles: Latissimus Dorsi, Quadratus Lumborum, Posterior Intercostals, Serratus Posterior, Iliocostalis Lumborum

All human beings have underlying L AIC pattern (except for a person who is born with situs inversus). some individual is going to move into a PEC pattern because of Lifestyle habits (how much they sit, stand, gait, etc), Genetics (such as hypermobility), Previous injury & the need to compensate around them, and Exercise/sports habits.

In my personal experience (seeing patients in NY and TX), I see more patients with L AIC or the extension of L AIC pattern in TX than in NY. On the other hand, I see more patients with PEC and the extension of the PEC pattern in NY than in TX. I believe this is because of differences in lifestyle, health awareness, and exercise habits.

In the PEC pattern, those muscles become tightened and lock your body. They compress the back side of our body and pull the pelvis forward on both sides.  As a result, we often see severe anterior pelvic tilts, excessive lumber curvature, and forward shift of the pelvis.


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Typical PRI “Left AIC”, “Right BC”, “Right TMCC” pattern

Left AIC pattern”, ”Right BC pattern”, ”Right TMCC...


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