The 90/90 Hip Shift with Alternating Crossover

This is the third article in a series, where we’ll cover the 90/90 Hip Shift with Alternating Crossover. The series covers the 90/90 Hip Lift and 90/90 Hip Shift positions. The other articles can be found here:

What Is It?

The 90/90 Hip Shift with Alternating Crossover is an exercise that is the theoretical third activity that can be progressed from a position originally known as the 90/90 Hip Lift. This is an exercise that is taken and modified from the Postural Restoration Institute, and is taught in the MyoKinematic and Pelvis Restoration courses (and perhaps the Postural Respiration course, depending on if it is brought up or not in the lab section).

For starters, here is a video detailing the step-by-step process for going from a 90/90 Hip Lift, to the 90/90 Hip Shift, to the 90/90 Hip Shift with Alternating Crossover (90/90 HS AC).

Integrating systems will be covered in this article in relation to the 90/90 Hip Shift. There are many variations with the 90/90 Hip Shift, and this article will go over combining many of the body’s systems versus simply adding variations for variations’ sake.

Background for Using This Exercise

Progressively, each subsequent version in the 90/90 series goes to lengths to impact the nervous system. At its simplest, the 90/90 HS AC is the most complete version of this pattern on a mechanical level.

However, further integration beyond does not only relegate its effects to only pressures of the thoracic diaphragm and pelvic floor/diaphragm, but seeks to further affect the brain and system’s ability to intake information of the world around it.

Yes, pressure is important, but nerves innervate these thoracic diaphragm and pelvic floor as well.

Ideally, you’d aim to work on the first couple easier versions of the movement – the 90/90 Hip Lift and 90/90 Hip Shift – before continuing with the 90/90 Hip Shift with Alternating Crossover.

There may be two points of reasoning for continuing with this exercise – either you need MORE stimulus to re-organize how your body moves, or you need a greater FOUNDATION before moving on to the neurological pieces that I will be describing below.

Populations That May Benefit

Integration can benefit many individuals – ideally I’d say, “everyone should want to achieve this level” of movement. However, there are certainly some individuals that may benefit more than others when looking to utilize the principles of integration into any exercise.

  • Individuals who may have had neck, cranial, or facial issues
  • Individuals who may have balance, dizziness, or vestibular issues
  • Individuals who may feel chronic tightness in neck
  • Individuals who may feel chronic tightness in hamstrings, calves (gastrocnemius), and arches of feet
  • Individuals who have had pelvic, sacroiliac, or lower back issues
  • Individuals who have had knee issues.
  • Individuals who may experience anxiety, especially in relation to movement related anxiety (return to play, returning from injury)

The reason these individuals may benefit more than others with integrating other systems is because in everyone, and perhaps even organismically, there are several systems at play when locomoting, and moving about the world.

Executing the 90/90 HS AC allows the user to begin to tap into the potential into the great amounts of interplay between the visual, vestibular, and somatosensory systems which to control the body on a postural level. (2, 3) Yes, there are certainly a lot of benefits that can be ascertained from this exercise on a biomechanical level – general knee “crankiness” may be relieved, hip issues may be relieved, etc. But I’d like to take this time to begin to identify the integrative nature of how the body works, especially just beyond a mechanical level of thought process.

The reasons why individuals who may have had neck, cranial, or facial injuries may benefit from these sorts of integrated exercises is multifaceted in nature, stemming from reasons in evolution of the vestibular system (4) and concepts involving sensory reweighting (5), which I’ll go over later in the article (and in a follow-up article).

Instructions for the 90/90 Hip Shift with Alternating Crossover

This is an image of the end position of the 90/90 Hip Shift with Alternating Crossover
90/90 Hip Shift with Alternating Crossover

Per the PRI Manual:

  1. Lie on your back with your feet on the wall and your hips and knees at a 90-degree angle.
  2. Inhale through your nose and as you exhale through your mouth, perform a pelvic tilt so that your tailbone is raised slightly off the mat. Keep your low back flat on the mat. Do not press your feet into the wall, instead dig down with your heels.
  3. Inhale through your nose and exhale through your mouth as you straighten your right leg and reach towards it with your left arm. You should feel your left abdominal muscles and the muscles on the back of your left thigh engage.
  4. Maintaining a pelvic tilt, bring your right foot back to the wall.
  5. Inhale through your nose and exhale through your mouth as you straighten your left leg and reach towards it with your right arm. You should feel your right abdominal muscles and the muscles on the back of the right thigh engage.
  6. Continue this sequence for 4-5 breaths with each leg.
  7. Relax and repeat 2 more times.
  • My own alterations include adding in a hip shifting maneuver before adding in the reaching component with the arms.
  • Further, the leg that is bent will be the “anchor” that maintains the stance position of the body. As the (3) instructs to “feel your left abdominal muscles and the muscles on the back of your left thigh engage,” this demonstrates that the left leg is the stance leg in this case, and the right foot will be reaching up towards the ceiling (in a hip shifting manner).

Levels of the 90/90 Hip Shift with Alternating Crossover

With all of these pieces of information of the “why” under your belt, the mechanical information of the gait cycle is laid out for you to dissect by asking yourself these questions.

  • If one leg is assuming a “mid-stance” position, what muscles must be sensed, and then activated?
  • If the other leg is in a “mid-stance” position, what is the other leg demonstrating?
  • What do the muscles involved with the swing phase of the gait cycle exhibit?
  • Can these phases of gait be reflected in the upper body and the upper extremity?
  • Can these phases of gait be reflected in the torso, ribcage, and spinal level?
On a general level, these are the arthrokinematic movements that should be coupled together during the designated phase in gait. (Further elaboration can be detailed in more nuanced phases of gait, along with detailing any dysfunctional or aberrant arthrokinematics.) (1)

Defining Integration

In order to understand what’s underneath the hood beyond a biomechanical level, you’ll need some introduction to how integration alters the system on a whole.

Integrate: /ˈin(t)əˌɡrāt/
combine (one thing) with another so that they become a whole.

Integration in this sense is not merely just the mashing of all the systems and selling it as a weekend course. More specifically, in order to further our understanding one step further, we’ll look to a few specific systems, and how they interrelate and interact with one another – the visual, vestibular, and somatosensory system.

These three systems contribute to postural control.

Mechanically, I’ve brought up several points and questions that point to greater biomechanical involvement with the gait cycle than simply just lower body movements occurring in order to propel the body forward. (see Asymmetry and the 90/90 Hip Shift). However, the body does not simply move better and differently after one repetition, and it may take several repetitions until something registers in the user’s brain that something is indeed different than before.

By sensing that the body is placed in a specific position, your body will assume a specific resting posture that will place the body in specific mechanical positions, and will call upon the resting musculature.

However, by placing the body in different positions while laying down, standing on two feet, standing on one leg, etc, the nervous system will be attuned to a different sense of “space” on a neurological level.

Receptive fields are found primarily in the visual, somatosensory, and auditory system. They provide input towards creating a "sense of space" of the external world, which is represented in the internal mind.

In the context of the sensory system, there are “afferent neurons” that will relay signals when a new stimulus is detected, and this will eventually alter the motor output.

For example, if you predict you are about to step into a hot shower, but it ends up being a cold shower, you’ll likely contract the muscles that are touching the water in a reflexive manner after you experience the drastic change in temperature.

Cortical Pathways for Afferent Neurons

But, instead of a shower’s temperature affecting the motor output of your body, I’m bringing up the idea that introducing a different stimulus (and sensation of this different position) can jumpstart the process for increasing bodily awareness, and then increasing movement efficiency. Further, this concept not only extends in the somatosensory system, but also extends to the visual and auditory system as well.

So, what does this concept look like, and what does this mean?

Defining Sensory Reweighting

We utilize different senses to navigate throughout our environment and our world. Simply, there are five senses to acknowledge – sight, smell, hearing, taste, and touch. However, we may not use the sense of smell nor the sense of taste to navigate our world to inform our movement decision making process. Rather, when we navigate our world we will primarily be using the senses of sight, touch, and the vestibular organs (found in the ear) to control our sense of balance and postural control during resting and dynamic movements.

However, what happens after an injury to the foot, knee, or hip? Will there be an alteration with how we navigate the world? Or perhaps an injury to the cranium, or degradation in the acuity of the visual system? Will everything be firing on all cylinders in equal values? Or will something adjust based on one sense being “dulled” and another sense increasing in sensitivity levels?

Sensory Reweighting: the process of adjusting the sensory contributions to balance control (3)

This is a graph demonstrating the difference between the visual, vestibular, and somatosensory systems in the context of "sensory reweighting."
Altered functioning of postural control may lead to over-dependence of the vestibular control, at the cost of less visual and somatosensory systems’ contribution to movement.

If there are three systems at play, there may be approximately 33% of each system being utilized at any given time for movement and dynamic control. (See column on left)

However, if there is an injury, reduction in sensitivity, or degradation of one of these systems, surely there will be a likewise adjustment in the other two systems as well. (See column on the right)

Integration of these systems is utilized to relieve some of these unnecessary demands, and re-organize how the body moves, walks, and performs many other movements as well.

In this case, the visual, vestibular, and somatosensory systems create a delicately balanced system with which postural balance is resting upon. Now, the visual and somatosensory systems primarily guide this sensing process, with the vestibular system being the “back-up” system with which to rely upon a “righting” system. (reference)

If you’ve ever seen anyone do a side plank and try to crank his or her neck into an upright position, you’ll understand what I mean here.

Side Plank with a Neck Turn
Side Plank with a Neck Turn

This side plank’s neck position doesn’t call for the individual to consciously activate the SCM and anterior scalene to laterally flex the neck, rather it may be a by-product of dependence on the vestibular system to “right” the visual system and confirm a position of being upright – even if the rest of the body is literally sideways.

So, the driver, or mechanism controlling the motor output, for movement in this case is the vestibular system, which is done on a subconscious and perhaps even dysfunctional manner. Applying this thought process, what other movements may see head and neck motions first to drive movement for the rest of the body?

That’s a great way to reinforce the vestibular system’s contribution to lifting something off the ground.

In other words, this neck strategy may not be the most advantageous strategy to call upon when aiming to improve upon your motor control of the rest of your body during deadlifting. Movement should be reinforced by co-contraction of the lower body musculature needs to be experienced by the appropriate musculature and not driven by the vestibular system.

So, what can you do? Do you just fix your neck position and call it a day? Can you just avoid any problematic positions?

This is not so simple. That is like putting multiple pieces of tape on something to keep it together, instead of simply re-evaluating how to replace the material altogether. The problem is still there, you just haven’t addressed it appropriately. Sometimes in order to arrive at a solution, you need to go through it, not around or avoid it.

So, with an exercise like the 90/90 HS AC, there is a large reliance on the somatosensory system to guide the movement, along with the eventual reduction in visual and vestibular dependence. Essentially by shifting a large amount of sensation to the muscles being used, the visual and vestibular system may be “relieved” of taking over the work and often a sense of “lightness” may be felt by the individual – because there was a large amount of sensation that was derived from dependence on the visual and vestibular systems, often the neck may be a contributing factor towards feeling “tight,” “heavy,” or just general unease or discomfort.

The picture on the far right (before) is essentially a forward head posture; if you orient the axis of body on the alignment of his pelvis, the head will be leaning forward ahead of the body, but rather it is being displayed with with excessive lumbar lordosis in upright posture.

With this said, perhaps the asymmetry I wrote about in previous articles may be attenuated or reduced by increasing somatosensory control, and reducing vestibular/visual dominance (especially in one side)!

Choosing to Integrate Systems

So, why choose to integrate multiple systems for a movement that can be largely viewed as mechanical? Does it have to be so difficult? 

The purpose is not to intentionally make things complex, but to go into a topic with the basic understanding that things may eventually become complicated. The willingness to understand and interpret information must be exhibited by the reader (or client), otherwise integration of these systems is an unnecessary endeavor. You can lead a horse to water, but you don’t need to explain to it the mechanisms for how water evaporates into the clouds, to eventually become rain. They should just drink it. If the horse asks, then you can explain it. 

So, when the student is ready, the teacher will appear.

With this said, integrating neurological stimuli is much more than just making them do an exercise with no attachment to the meaning of why they are doing the movement.

By introducing a neurological stimulus, you will be guiding the client, patient, or athlete to create a new experience, ultimately one that they have never experienced before. In other words, by introducing a new or previously unattended to visual or sensory stimulus to the body, and then tasking the body to move, you’ll be introducing something that they have either forgotten (re-introducing the stimulus), or have never experienced (a novel stimulus).

But a novel stimulus is not the sole purpose of these movements. However, this novel stimulus is an introduction to the learning process of the individual, ultimately affecting how they view their internal self, their external world, and the way they experience life.

So, instinctively when coaching athletes in a 90/90 Hip Shift, I walk them through how to mechanically achieve certain positions, but I also recognize that my clients and athletes aren’t such a simple organisms – they aren’t machines or robots that work with mere inputs and outputs.

However, the body is sensitive enough to recognize if there is something as small as a hair brushing up on your face, if something is touching your leg (and what intensity), or if something moves quickly in the left or right side of the individual’s peripheral vision. This is in contrast to when you grip something with lots of tension to prevent it from falling.

Ultimately, your body won’t react to have a buffering system of higher or lower amounts of sensitivity if it isn’t referencing, or has the awareness, of said body part to do the action.

The reason I bring this is up is that there are stimuli that can elicit a greater or lesser reaction based on what the interpretation of that stimulus is – and that leads into more discussion on feedforward and feedback loops of the nervous system – which ultimately leads to learning how to increase or decrease their responses based on whatever stimuli is introduced into their system!

In Review

  1. The 90/90 Hip Shift with Alternating Crossover is the next progression on a biomechanical level (for this series).
  2. Integrating the feet into the movement is crucial to altering somatosensory input into the body (as the feet are truly the only thing to deliver information to the body when walking – you don’t walk with knees on the ground, or your face either).
  3. The 90/90 HS AC (and other unilateral exercises) can aim to restore somatosensory system that may affect one side of the body, as well.
  4. Afferent neurons and the associated cortical pathways allow for sensation to occur, which may be a precursor before motor output occurs.
  5. Essentially, you’ll often need to sense before you can move – and this dates to when you are going through the developmental process as a baby. (If you don’t build an effective understanding of how to relate to your body as you develop, you’ll likely have a difficult time sensing and moving as you grow into adulthood.)
  6. The 90/90 HS AC activity, among with many other integrative exercises, allows for greater sensory reweighting to occur, which can alter the contribution levels of the visual, vestibular, and somatosensory system to postural, and eventual, dynamic control.
  7. By reinforcing greater somatosensory control, there can be a reduction in the vestibular system’s contribution to “uprighting” the body, which can help relieve tonicity in various regions in the body.
  8. In a similar fashion, by reinforcing greater somatosensory control, there can be a reduction in a need for the visual system dominance, which can reduce forward head posture, squinting, migraines, headaches, and it does so by upregulation of the parasympathetic nervous system.
    1. Appropriate cortical mapping is important towards building subconscious awareness, which will then build upon the motor outputs necessary towards any specific goal.

With this amount of information available, it is my hope that you begin to see that simple biomechanical issues are not just simple biomechanical problems – they can spiral into complex neurological and evolutionary based pieces of information. By relating it back to an exercise, such as the 90/90 HS AC, I hope to make this information relatable, and informative to guiding your practice and clinic.

As always,
Keep it funky.


1 – Michaud, Thomas C. Human Locomotion: the Conservative Management of Gait-Related Disorders. Newton Biomechanics, 2011.

2 – Kandel, Eric R., et al. Principles of Neural Science. McGraw-Hill Medical, 2014.

3 – Shumway-Cook, Anne, and Marjorie H. Woollacott. Motor Control: Translating Research into Clinical Practice. Wolters Kluwer, 2017.

4 – Graf W.M. (2009) Evolution of the Vestibular System. In: Binder M.D., Hirokawa N., Windhorst U. (eds) Encyclopedia of Neuroscience. Springer, Berlin, Heidelberg

5 – Assländer, Lorenz, and Robert J. Peterka. “Sensory reweighting dynamics in human postural control.” Journal of neurophysiology 111.9 (2014): 1852-1864.APA