The movement is driven by the lower body so the forward reach stays stable and balanced. The arms should move to meet the thigh angle, so the reach is produced by hip and knee positioning rather than bending the trunk or hitching the shoulders. When the arm angle mirrors the thigh angle, the pelvis and rib cage stay stacked and the spine stays neutral, minimizing compensations. Reaching with the trunk, hips, or shoulders would shift load away from the legs and create unwanted spinal or rib flare, whereas matching the thigh angle keeps the pattern cohesive and controlled.

In PRI, the most important reference center is the left internal obliques and Transversus Abdominis teamed with the left posterior lower rib cage because this pair anchors the thoraco-pelvic cylinder that guides the entire left-sided posture. Activating the left IO/TA helps create a stable, inwardly braced core, while positioning the left posterior lower ribs supports the rib cage in a orientation that accommodates the pelvis to balance and rotate appropriately. This combination provides the strongest, most consistent cue for aligning the rib cage over the pelvis and driving the left pattern (often described as the left AIC side of the system), making it the central reference point clinicians rely on for retraining and cueing. Other reference points, like a particular foot bony landmark, a specific rib position on the opposite side, or a hip capsule cue, can be helpful in certain drills or as secondary cues, but they do not exert the same overarching influence on the rib-pelvis relationship and dynamic as the left IO/TA with the left posterior lower ribs.

Transverse mobility works best when the body has a solid fronal (frontal plane) stability base in the lower thorax through the hips and pelvis. In PRI, rotational movement is most efficient once the frontal plane strength in that region is well established, because a stable axis allows the trunk to rotate without collapsing the pelvis or rib cage. If the frontal plane system isn’t developed there, attempting transverse mobility risks compensations and misalignment, rather than clean rotation. This is why the statement that transverse mobility can be used only when frontal plane strength is well established below T8 through the hips and pelvis is the best fit. Options that rely on ankle flexibility alone, claim independence from strength, or suggest mobility can occur without any frontal plane control don’t fit how PRI views the organize-and-mupport system necessary for rotation.

In Left AIC myokinematic restoration, the four phases are a progressive re-education of how the stance legs and pelvis work together to create alternating reciprocal motion. The pattern starts with repositioning to set the pelvis and hips for effective training, then retrains the left stance, then retrains the right stance, and finishes by consolidating with the right stance again so both sides can cycle properly. The sequence begins with the left leg in left AF IR to bias the pelvis toward the starting orientation that supports the left AIC pattern. Next, you retrain the left stance in that same left AF IR position to reinforce stable loading and correct left-sided stance mechanics. Then you move to retraining the right stance, described as the right leg in left AF IR (or the left AF ER) to encourage the pelvis to shift and rotate in a way that supports reciprocal motion. Finally, you finish with the right leg in right AF IR to complete the bilateral retraining and lock in the corrected pattern, with both legs in right AF IR promoting symmetrical function. This exact progression—repositioning, left stance retraining, right stance retraining, then finishing with right stance retraining and the corresponding leg orientations—best matches the four-phase approach for a Left AIC pattern. The other sequences either mix in dual-stance training, start with the wrong leg orientation, or end with an incomplete pattern, which undermines the goal of restoring alternating reciprocal motion.