**4.1. Repositioning for sagittal plane neutrality**

The PRI protocols begin with establishing the patient's ability to achieve sagittal plane neutral position of the pelvis and the ribcage. As previously described, this means that in a position of rest, their musculoskeletal system is in a state of relative muscle balance following a "repositioning" activity. Sagittal plane repositioning is most easily achieved in supported positions. Gravity is thereby eliminated and underused muscles can be positionally isolated and challenged.

Recruitment of the hamstring muscles is the most common starting point for repositioning exercises. The hamstring muscles insert proximally on the ischial tuberosity and distally on the medial tibial condyle and on the head of the fibula and the lateral tibial condyle. When the pelvis tilts anteriorly, the ischial tuberosity moves proximally and away from the tibia, resulting in overlengthening and weakening of the hamstring complex. Consequently, this powerful muscle group is unable to perform its postural function of stabilizing the pelvis, especially during stance phase of gait. Assessing ADT or another relevant test, prior to and following the activity, demonstrates whether that activity was helpful in restoring correct hamstring length and neutral pelvic alignment. If so, it is useful to ask the patient to stand and describe their body sensation to assure a definitive, proprioceptive experience of difference. Some patients, especially people with hypermobility, have difficulty noticing subtle differences. Others notice new sensations: "I feel lighter, taller, more weight on my heels."

The skill of sensing, i.e., the ability to focus attention on subtle sensations, is a potent tool for reshaping one's alignment from within. These sensations include awareness of the ground, of the body's orientation in space, internal structural relationship, and subtle changes in muscle tone. Most empowering is the ability to achieve expansion of targeted thoracic regions on inhalation.
