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.

References

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

Calls in a Car with Coaches – Episode 002

This is a throwback “Calls in a Car with Coaches” episode (June 2019), where I discuss sprinting, social media, and training overall. Technically, it is Episode 002, just haven’t gotten around to editing it until now!

I find this information to be relevant to look back on, as much of how we have been interacting and consuming information has been 99% social media due to quarantine and COVID.

Hope you enjoy!

As always,

Keep it funky.

Asymmetry and the 90/90 Hip Shift

This is an article on the 90/90 Hip Shift, and is the second part of a four part series involving the 90/90 Hip Lift and beyond. The first part may be found here:

Understanding How Your Body Moves

This describes the neural pathway for the brain to send signals to skeletal muscles.

So, the brain senses and sends signals to muscles. Then, these muscles pull on bones, and if given enough proximal stability in one area, then the distal region of that same bone will begin to move. Then, the bones’ joint articulations will touch and approximate on another joint, which will allow for specific ranges of motion to be expressed.

When the femur goes into flexion relative to the acetabulum, the femur needs to move posteriorly within the hip capsule.

For example, if the brain sends motor signals to the hip internal rotators to move, the muscle fibers of the hip internal rotators will begin to rotate the femur within the hip. Then, once the femur reaches its end range of motion within the acetabulum, if there is more desire to move than is expressed, there may be excessive (or inefficient) movement found at the knee (where the distal femur articulates with the tibial plateau), or further in up beyond the pelvis (in the lower back, for example).

Hip Internal Rotation is expressed by the femur moving posteriorly within the hip capsule. If movement is limited here, where else will movement occur?

Now, extend this concept globally to the whole body, and not just at a singular joint. If your body tends to have a right sided bias, and a rotary component leaves your body with the above ROM…

…is it possible to inhibit musculature that is leaving your right shoulder with a lack of internal rotation, without directly affecting the specific area? I’d argue yes, you can.

The reason being is that your arm is simply not experiencing a lack of shoulder internal rotation, but it is also experiencing a lack of trunk rotation (to one side), a lack of hip rotation (in one side), along with possible cervical rotation asymmetries.

Further, there may even be different values found at the ankle region for supination, pronation, dorsiflexion, and plantarflexion. All these reasons could be potential reasons why there is a lack of shoulder internal rotation deficit, which could, and should be accounted for as well.

There is an asymmetry found in all individuals, and it is expressed in greater detail in athletes that play rotationally demanding sports.
What does thoracic rotation, tibial rotation, ankle supination/pronation, etc look like in this individual?

With this said, perhaps an exercise can identify how to restore trunk rotation, cervical rotation, hip rotation, and ankle motion, which will then allow your shoulder internal rotation to be restored – without even doing an arm exercise to begin with.

Your body works integratively, and it can recognize when there is greater range of motion in another area adjacent (or not adjacent) to it, which will allow your body free up movement in said adjacent area. At its simplest, this phenomenon is called regional interdependence.  (1) Other models may discuss this within the context of self-organization and motor control. (2)

There are certainly many different exercises that can improve upon shoulder internal rotation via the principles of regional interdependence, neuromuscular adaptations, and motor control.

With this said, I’ll be discussing the 90/90 Hip Shift from the Postural Restoration Institute.

What is the 90/90 Hip Shift?

The 90/90 Hip Shift is another foundational exercise from the Postural Restoration Institute (PRI). Much like the 90/90 Hip Lift, the 90/90 Hip Shift is also often taught in the foundational courses from PRI, and is the next level used to help integrate the body together.

The 90/90 Hip Shift is performed in a supine position (on your back), with your feet on an elevated surface, and knees in a flexed (or bent) position.

More often than not you’ll have something between your knees, not just as a formality, but used to help feel and sense differences in position between one leg’s position, and another leg’s position.

At the end of the day, this exercise is a neurologically based exercise, that is often utilized to identify and treat biomechanical issues that arise from lower body, the lumbar spine, along with any knee issues as it relates to force absorption, along with subconscious movement (such as activities of daily living, walking, running). I bring up the subconscious aspect because by performing this activity, you don’t need to constantly monitor movements day to day, watching every movement and every activity that you perform.

Populations That May Benefit

  • Athletes that utilize asymmetrical patterning (throwing, one-handedness, rotational athletes, track athletes that sprint on the track, etc)
  • Individuals that are asymmetrically biased for work or in activities of daily living (drivers, individuals who carry bags on one side all day)
  • Individuals that may have an injury on one side (lower body, thoracolumbar asymmetry, etc)
  • Individuals that may be experiencing a lack of shoulder internal rotation
  • Individuals that may be experiencing hip impingement-like symptoms with hip flexion and hip internal rotation
A closing angle joint pain or hip impingement with hip flexion and adduction may be an indication to utilize these asymmetrical strategies.

Purpose for Using This Exercise

So the purpose behind using the 90/90 Hip Shift is a bit different than a simple bilaterally based exercise (such as the 90/90 Hip Lift), which did not bias towards one specific side.

In this case, the 90/90 Hip Shift is an exercise that can re-orient the nervous system to account for the potential biomechanical discrepancies that may be present, and improve upon the nervous system’s ability to self-organize and locomote.

Further, much like I explained in the first article (The 90/90 Hip Lift), there are kinesiological asymmetrical differences in the right versus left side of the human body.

Heart on the left, liver on the right, and a diaphragm that has a larger crus attachment on the right side.

The 90/90 Hip Shift is an exercise that is aiming to improve upon this natural asymmetry in the body, prior to any further behavioral asymmetries exacerbate into an orthopedic problem. Or, in other words, this exercise’s purpose is to reduce any physical discomfort or problems brought about by this one-sidedness, and hopefully address it before any more difficult problems arise (bony impingements, capsular problems, etc).

Instructions for the 90/90 Hip Shift

PRI Instructions Verbatim:

  1. Lie on your back with your feet flat on a wall and your knees and hips bent at a 90- degree angle.
  2. Place a 4-6 inch ball between your knees.
  3. Inhale through your nose and exhale through your mouth, performing a pelvic tilt so that your tailbone is raised slightly off the mat. Keep your back flat on the mat.
  4. As you maintain a hip lift, shift your left hip down and your right hip up so that your right knee is slightly above the left.
  5. Slowly take your bent right leg on and off the wall so that your right thigh comes toward your chest. You should feel the muscles behind your left thigh and left inner thigh engage.
  6. Perform 3 sets of 10 repetitions, 1-2 times a day.
  7. Repeat for other side (my instructions).

Competency in the 90/90 Hip Shift

The next step involves understanding how to hold the previous movements’ lessons, and how to incorporate the next components involved with the 90/90 Hip Shift.

Table B: Movements of the 90/90 Hip Shift (into the right side) with a picture of the beginning position of the 90/90 Hip Shift

With Table B, there are roughly 13 items that need to take place before moving on. If they don’t take place, can you really say you’ve achieved an authentic 90/90 Hip Shift? Some other questions to help improve confidence in the acquisition of these motor strategies involve:

  • Achieving hip adduction in one side, with concomitant hip internal rotation may further stabilize and anchor the leg (side A).
  • While you’re achieving hip adduction of the femur and hip internal rotation on one side, can you also acquire hip abduction and hip external rotation of the other side (Side B)?
  • Can you confidently say you’ve achieved these items (in Table B) without losing the original 90/90 Hip Lift position as well?
  • Can you say you’ve achieved an appropriate zone of apposition if your accessory neck musculature helps breathing during these unilaterally based movements?

Biomechanical Reasoning

So, if a rotational athlete (baseball player, tennis player, etc) performs hundreds to thousands of rotations to improve at their sport (hitting, throwing, etc), chances are they will begin to create a body that is made for that sport. In other words, there will be soft tissue adaptations, and more likely structural adaptations, that will allow the individual to excel at the sport they are playing.

Structural adaptations, or neurological adaptations…?

There may even be differences from dominant arm to non-dominant arm, along with ability to rotate (trunk rotation) which measures the ability for the spinal vertebrae to rotate, along with lower body contribution to performance based asymmetries found in the body. (3) (4) (5) (6) (7)

Let’s say we hypothetically have a baseball pitcher with the following upper body range of motion (ROM) values:

Right Handed Pitcher (High School/College)

  • Supine Shoulder Internal Rotation (Right): 45°
  • Supine Shoulder External Rotation (Right): 130°
  • Total Shoulder Motion (Right): 165°
  • Supine Shoulder Internal Rotation (Left): 90°
  • Supine Shoulder External Rotation (Left): 100°
  • Total Shoulder Motion (Left): 190°

At first glance, this may make sense – the right-sided dominance (right hand pitcher) may exhibit greater range of motion in shoulder external rotation due to pitching demands, and likewise decreased motion in shoulder internal rotation due to the eccentric control found from throwing.

You do all of the “correct” things a practitioner would do in this situation – no bench pressing, no pull-ups, no barbell back squatting, etc. This is done to prevent any biomechanical issues in the weight room from exacerbating the sports specific movement found in the field.

Further, you also pay attention to evidence based research, and understand the differences within the context of GIRD (glenohumeral internal rotation deficit), which accounts for the bony adaptations (Wolf’s Law) found through repetitive force and stress on the body. The SAID principle dictates that “the human body adapts specifically to imposed demands.” All of this holds water, because if there are structural adaptations, they will be present in the body when properly identified through passive ROM assessment.

However, what happens if there are surgeries, procedures, or techniques that have slight risk with them (eg, dry needling, manipulation, etc) that focus on improving these often debilitating or painful regions of the body, when in reality those areas are a result of this asymmetry? Is it possible to restore this asymmetry, and forego any detrimental procedures that can’t be taken back?

To take it to the next level, there can even be DEXA scans to identify different bone mineral density in the whole body, which, if I were to surmise, there would be greater bone density in the dominant arm and dominant leg (the left leg for right handed pitchers, athletes, etc.) (13)

A DEXA scan can identify density of your bones between different regions of your body, including left and right asymmetries. (Ireland)

Even with DEXA scan identifying differences in greater bone mass in one region versus the other, is it possible to restore neurological asymmetry despite structural asymmetry?

So, what do you do with this information? Do you simply let it go, and assume it can’t be changed? What if there is something you can do to improve upon one region of the body, in order to affect another region of the body (indirectly)?

My purpose here is to hopefully say yes, and begin to re-allocate physical stressors asymmetrically, and to stress the other side as well.

90/90 Hip Shift and the Gait Cycle

For ease of understanding the 90/90 Hip Shift, the purpose of shifting femurs and hips is reminiscent of the gait cycle, more specifically swing and stances found in the lower body.

The phases of the gait cycle

Understanding the basics of the gait cycle will allow one to understand what is specifically going on with the 90/90 Hip Shift. Specifically, there are two phases of gait that are important here – stance, and swing. These two phases are not only evident in walking, but it is also translatable towards movements in the gym.

With respect to the 90/90 Hip Shift, there are ALSO two phases of gait. When one side is “weight-bearing” it is in the stance phase, and the “swing” phase is experienced on the other side. This is also reflective of the musculature that is synonymous with swing and stance phases of the gait cycle.

For example, when performing a 90/90 Hip Shift on the right side of the body, the foot is integrated and in a mid-stance position with the foot experiencing the windlass mechanism, along with the adductors, well adducting, and hamstrings stabilizing a pelvis on top of a stabilized foot.

This side is weight bearing, thus it is in the “stance phase of the gait cycle.”

With the left side of the body, the foot should experience a degree of supination, with concomitant left femoralacetabular (FA) external rotation.

90/90 Hip Shift on the Right Side

The gait cycle involves more than just the thighs moving underneath a torso and upper limbs flailing about. Rather, movements in the gait cycle are also reflected in the…

  • Thoracic region
  • Pelvic girdle
  • Tibiofemoral joint
  • Ankle complex

The execution of the 90/90 Hip Shift is similar to the 90/90 Hip Lift, in that that the first components of the movement need to be obtained. So, if you need to teach your body how to perform a posterior pelvic tilt, you will often need to acquire that motor skill before performing the 90/90 Hip Shift, because it is a bit more nuanced than simply getting “global” motion on both sides.

The “Why” Behind Integration in the 90/90 Hip Shift

Integration on a mechanical level involves not just respecting the lower body’s contribution to the gait cycle, but also the upper body’s limbs, trunk stabilization, and acceleration of all of these pieces as well. In fact, upper and lower body limb movements are coupled (or working together) despite the upper body being immobilized in this specific study. (8)

Walking is much more than feet just hitting the ground.

Now, before the argument for training these movements is reduced to “this is simply the gait cycle,” understand that the body does much more than place one foot in front of the other.

With this said, the bipedal nature of the gait cycle is quite literally an evolution out of our quadruped primate ancestors. (9) There are certain features that are borne out of an evolution towards a bipedal gait cycle. These involve different depths of joint sockets, the different densities of certain bones such as the vertebrae, femurs, and tarsal bones, which all allow for greater ability to weight bear, along with many other structural items that dictate greater access to not just walking on two feet, but also the need to hold, grasp, and manipulate items with our hands.

Further, there is understanding that altering stride frequency, stride length, along with understanding the kinetic and potential energies involved with bipedal walking allows us to understand how this evolution is beneficial towards energy consumption as well. (10)

So, with all this being said, understanding everything above the pelvis (trunk and upper limb contribution) is also important towards completing your understanding of the gait cycle. (11) (12)

Performing Both Sides of the 90/90 Hip Shift

Now, I realize I made an argument for identifying asymmetry on one side of the body, particularly a right-sided asymmetry, especially those that may be involved with rotational sports. However, there is more than just a structural or kinesiological asymmetry present in our bodies, but rather there is a neurological asymmetry present with our brains and how it delivers information, and receives information as well.

With this said, there is a huge contention within those that are merely exposed to a little bit of information from PRI that when you do the 90/90 Hip Shift, or almost any asymmetrical exercise within this context, that you need to only acquire the left side of the body. I’ll address this here and now:

Acquire competency in the right side of the body first.

Yes, it is understood that range of motion that is being assessed, and it is often expressed in a unilaterally and asymmetrically biased fashion.

However, if there is “competent” control of the right side of the body, then going into femoralacetabular (FA) internal rotation, femoralacetabular (FA) adduction (among other movements), then surely you would also have adequate and “competent” control of the other side (left side) of the opposite movements – FA external rotation and FA abduction. If you don’t have authentically own a right side, then you surely don’t authentically own a left side.

So in layman’s words – you need to express range of motion in your right side, before continuing onto the left side of your body. The right side of your body may have the capacity to express certain ranges of motion, but this may be only due to the biological differences that are found in your body, not through willful motor competence.

To be clear, an individual who is expressing an asymmetrical pattern (such as right-sided or right dominant motor control or ranges of motion) is often moving secondary to a neurological and asymmetrically oriented pattern found in the brain. They are neither in control of their right nor left side – but rather they are moving without appropriate executive control of their body. To “own” both sides, you’ll need to first master one side – and by mastering one of these sides, you will be that much closer to owning the next side.

In Review

  1. Understanding that there are asymmetries in the body, regional interdependence, among other principles, allows a practitioner to improve ROM in one region of the body, without necessarily affecting area directly.
  2. Athletes and other individuals who use one side consistently and constantly may experience a greater expression of these asymmetries via ROM throughout the body.
  3. This exercise, among many others, is aiming to replicate the biomechanical, musculoskelatal, and neurological stresses that are experienced in the gait cycle.
  4. Re-orienting the body’s position can help self-organize one region of the body in order to reduce stress and improve degrees of freedom in another region of the body.
  5. It may be possible to identify these asymmetries through bony adaptations through a DEXA scan.
  6. The nature of walking with two limbs (bipedal) is borne out of an evolutionary development, and its processes can reflect metabolic efficiency, along with greater ability to manipulate and grasp tools, along with communication.
  7. Acquiring one side of the body on a neuromuscular level may be more advantageous due to the natural bias that is in place from kinesiology – aka acquisition of the right side of the body.

Admittedly, this is a lot of information to digest. But after taking close to twenty Postural Restoration Institute courses, this is the bulk of reasoning that I can offer when speaking about the 90/90 Hip Shift, and postural (and neurological) asymmetry.

Stay tuned for the next article, where I’ll go over integration beyond biomechanics in the 90/90 Hip Shift.

As always,
Keep it funky.

References

1 – Wainner, Robert S., et al. “Regional interdependence: a musculoskeletal examination model whose time has come.” (2007): 658-660.

2- Davids, Keith. “The constraints-based approach to motor learning: Implications for a non-linear pedagogy in sport and physical education.” Motor Learning in Practice. Routledge, 2010. 23-36.

3 – Robb, Andrew J., et al. “Passive ranges of motion of the hips and their relationship with pitching biomechanics and ball velocity in professional baseball pitchers.” The American journal of sports medicine 38.12 (2010): 2487-2493.

4 – Laudner, Kevin, et al. “Thoracolumbar range of motion in baseball pitchers and position players.” International journal of sports physical therapy 8.6 (2013): 777.

5 – Freehill, Michael T., et al. “Glenohumeral range of motion in major league pitchers: changes over the playing season.” Sports health 3.1 (2011): 97-104.

6 – Ryan, Gary J., and Andrew J. Harrison. “Technical adaptations of competitive sprinters induced by bend running.” New Studies in Athletics 18.4 (2003): 57-70.

7 – Roetert, E. PAUL, TODD S. Ellenbecker, and SCOTT W. Brown. “Shoulder internal and external rotation range of motion in nationally ranked junior tennis players: a longitudinal analysis.” Journal of Strength and Conditioning Research 14.2 (2000): 140-143.

8 – Kuhtz-Buschbeck, Johann Peter, and Antonia Frendel. “Stable Patterns of Upper Limb Muscle Activation in Different Conditions of Human Walking.” Brazilian Journal of Motor Behavior, vol. 9, no. 1, 2015, doi:10.20338/bjmb.2015-0005.

9 – Ceunen, Erik, et al. “On the Origin of Interoception.” Frontiers in Psychology, vol. 7, 2016, doi:10.3389/fpsyg.2016.00743.

10 – Vaughan, Christopher L. “Theories of bipedal walking: an odyssey.” Journal of biomechanics 36.4 (2003): 513-523.

11 – Nott, Cameron R., et al. “All joint moments significantly contribute to trunk angular acceleration.” Journal of biomechanics 43.13 (2010): 2648-2652.

12 – Goudriaan, Marije, et al. “Arm Swing in Human Walking: What Is Their Drive?” Gait & Posture, vol. 40, no. 2, 2014, pp. 321–326., doi:10.1016/j.gaitpost.2014.04.204.

13 – Ireland, Alex, et al. “Upper limb muscle–bone asymmetries and bone adaptation in elite youth tennis players.” Medicine & Science in Sports & Exercise 45.9 (2013): 1749-1758.APA