A Comparison of Different Commercial Models of Movement Assessment: Part II
In part I, we covered the The Selective Functional Movement Assessment (SFMA). Here, we’ll discuss the Postural Restoration Institute® (PRI). PRI is composed of multiple courses but for the sake of this discussion. I’ll focus on Myokinematic Restoration, Postural Respiration, and Impingement and Instability. Collectively, these three courses cover the biomechanics of the thorax, pelvis, and extremities in tremendous depth. Posture has become a dirty word in rehabilitation lately because static posture has not been demonstrated to correlate much with pain. Operationally defining “posture” is an article in itself but suffice to say, PRI does not advocate having people stand still while a clinician measures deviations from a plum line. PRI defines posture as a behavioral manifestation of the neuromuscular system. In this sense, posture is a dynamic behavioral output that is reflective of any sensory input that can influence movement. As movement professionals, our job is to change motor behavior to decrease pain and elicit physiological adaptations that increase resiliency. A better word for posture as elucidated by PRI is position. Position is fluid. While posture as traditionally defined may not matter much, position always matters. Position is the foundation of sport and the currency of movement.
One of the key tenets of PRI is the emphasis on asymmetrical motor patterns, right lateralization in particular. Right lateralization is not problematic in itself but often emerges as the default motor pattern under physical or emotional stress. Overdependence on right lateralization can decrease movement variability and lead to predictable biomechanical compensations. For example, why do more lateral superior hip impingements occur on the right side compared to the left? PRI’s emphasis on asymmetrical biomechanics at the pelvis and thorax helps to answer this question.
Asymmetrical anatomy does not always matter which is why PRI relies on objective tests (most of which are already familiar to orthopedically trained clinicians) to dictate interventions. The idea that proximal stability affects distal mobility is relatively accepted. PRI takes this concept a step further by suggesting that proximal stability controls proximal orientation. In the case of the hip and shoulder, proximal orientation refers to the position of the acetabulum and glenoid relative to the femur and humerus respectively. When the orientation of the proximal segment differs on one side compared to the other, so too will the end feel at the distal segments. Without appreciating orientation, one could easily mistake a positional problem for a joint restriction. Imagine trying to shut a door on a doorframe that is canted. One of the corners of the door is likely to run into the doorframe.
The answer here is not to try to slam the door shut or oil the hinges, but to alter the orientation of the doorframe. Only then would it make sense to do the door equivalent of a joint or capsular manipulation provided a restriction still remained. Without “neutral” proximal orientation, any type of traditional orthopedic assessment could be misleading. Like any behavioral expression, proximal orientation is changeable when the nervous system receives a salient message. PRI’s manual techniques and exercises focus primarily on developing low threshold (local/tonic/non-fatiguing/small motor units) motor control proximally to alter the positional relationship with the extremities. The goal is ultimately to restore equivalent rotational capability on an asymmetrical body, which early in the treatment progression is achieved by performing asymmetrical activities.
Later on, however, similar activities are performed on both sides. The goal in any movement should be to utilize only as much muscular activity as is necessary to perform a task safely. People often resort to high threshold strategies (global/phasic/fatiguing/large motor units) when they are not necessary. High threshold strategies are especially prevalent in people in pain because the nervous system recruits prime movers as stabilizers to minimize joint excursion in an effort to mitigate perceived threat. Often, this protective response is more of a problem than actual tissue damage. PRI incorporates controlled breathing into many of its exercises to reinforce low threshold strategies in non-threatening positions.
Additionally, these positions bias air into areas of the thorax that typically fill less than others during inhalation. Airflow thus serves as a potent sensory input that alters motor output via an autonomic mechanism we probably don’t completely understand. Full exhalation is emphasized to recruit the deep abdominal muscles and allow for greater diaphragmatic excursion during ventilation. To be clear, the autonomic changes that occur with controlled breathing as practiced in yoga, meditation, PRI, and the like are not associated with a particular phase of the ventilatory cycle. Inhalation and exhalation are not concomitant with sympathetic or parasympathetic activity per se. The nature of the entire breath cycle matters more than focusing on one particular component. PRI can be very powerful because by addressing global patterns/behaviors, multiple “problem” areas often clean up with a single intervention.
The emphasis on proximal position and orientation also helps ensure that limited range of motion is not mistakenly treated as a tissue restriction as occurs with many special tests. Nevertheless, localized issues do not always respond to global interventions, which is why traditional orthopedic testing and manual therapy remain very important. References are included below to expound on the concepts of movement variability, right lateralization, orientation and joint rotation, and controlled breathing. Stay tuned for part III, where we’ll discuss Functional Range Conditioning. References:
- Effect of changes in pelvic tilt on range of motion to impingement and radiographic parameters of acetabular morphologic characteristics.
- Comparison of changes in the contraction of the lateral abdominal muscles between the abdominal drawing-in maneuver and breathe held at the maximum expiratory level.
- Physiology of long pranayamic breathing: Neural respiratory elements may provide a mechanism that explains how slow deep breathing shifts the autonomic nervous system.
- The functions of breathing and its dysfunctions and their relationship to breathing therapy.
- Coordinative variability and overuse injury.
- The relationship between excursion of the diaphragm and curvatures of the spinal column in mouth breathing children.
- Analysis of preexistent vertebral rotation in the normal spine.
- Right thoracic curvature in the normal spine.
- The relation between organ anatomy and pre-existent vertebral rotation in the normal spine: magnetic resonance imaging study in humans with situs inversus totalis.
- Postural function of the diaphragm in persons with and without chronic low back pain.
- The Effect of Diaphragmatic Breathing on Attention, Negative Affect and Stress in Healthy Adults.
- The effects of specific respiratory rates on heart rate and heart rate variability.
- Immediate effect of slow pace bhastrika pranayama on blood pressure and heart rate.
- Autonomic responses to breath holding and its variations following pranayama.
- Effect of short-term practice of breathing exercises on autonomic functions in normal human volunteers.
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