Part 2/2: Axial Skeleton Archetypes
This is a follow up to my previous article on biotensegrity. Part 1/2 can be read here.
Humans are incredibly complex. There are a number factors to consider during rehab and training, but we must focus on interventions that make the greatest impact. Practically, we should be able to expand and contract our boundaries based on how the patient presents. This doesn’t mean that we can neglect other considerations; it means that we should place emphasis on the most relevant factors and cater our treatments accordingly.
As a means to simplify, I am offering up 5 broad categories that are common in musculoskeletal Physical Therapy. All categories always matter, but we can emphasize what is most relevant for the patient at hand.
Mental Factors
Psychosocial-emotional involvement – mind-body interaction as explained by psychoneuroimmunology. Stress can lead to central sensitization, hyperalgesia and allodynia (ex. unhealthy beliefs about pain, chronic psychological stress).
Physical Factors
Load management issue – inappropriate training loads or low work capacity. Over- and under- training are both associated with increased injury risk (ex. ‘training error’ while preparing for a marathon, poor aerobic fitness leading to overuse injury).
Tissue healing – tissue disruption and the associated stages of healing. Typically nociceptive or peripheral neurogenic pain (ex. post-surgical rehab, muscle strain or nerve injury).
Disease and lifestyle – medical conditions and lifestyle factors linked to the patient’s pain. Includes diet, sleep, physical activity, smoking, alcohol consumption and BMI (ex. inflammatory bowel disease and back pain, adverse effect of smoking on tissue repair).
Movement limitations – broad category that includes all mechanically driven pain. Movement variability and efficiency are the two targets (ex. limited overhead mobility in Olympic lifter, poor lumbo-pelvic control in soccer player).
Addressing movement limitations will be the focus of today’s article.
Coordinative Variability and Movement
Coordinative variability requires deviation in the delivery of a skill but consistency with the endpoint of a movement – the movement path is variable, but the outcome is the same. Expert movers have a high coordinative variability when performing their craft (1)(2). This is a desirable trait, but only up to a certain point – too little and too much variability is associated with increased injury risk (1)(2). As a result, our therapeutic goal should be to provide control through as many degrees of freedom as possible keeping specificity in mind. By doing so, we give the human system an opportunity to choose the best strategy that is dictated by the task and environment. Having options for movement is what leads to a healthy, adaptable system. A loss of options results in repeated force vectors, which could lead to overuse injuries and tissue breakdown (1)(2). Variable distribution of force could prevent “pattern overload” and build tolerance in different lines of tissue (1)(2).
Injury and pain can also limit movement variability (1)(2). When we have painful structures or patterns, our body has a difficult time accessing certain movements. This becomes problematic over time, especially if we develop rigid movement strategies and are fixed to a limited number of paths. Our nervous system ends up confining us and triggers a perception of threat in unfamiliar ranges or vectors. Ultimately, invariable movement could be both a cause and effect of pain.
How Exercise Effects Variability
Every exercise has a secondary consequence on our movement variability. Performing high-threshold activities like sprinting can also limit our movement options. This isn’t necessarily a bad thing, but sport programming and movement strategies should be considered in the context of rehabilitation. I believe that these changes are driven by physics and neuroscience. Relative motion and shape change are caused by altering tone and pressure gradients within viscoelastic tissue.
Broadly speaking, we have two goals when applying exercises in rehabilitation and performance training. In rehabilitation, our intention is to expand total variability of the organism in order to recapture health (3). In this context, poorly selected exercises can actually steal variability and lead to further compensation. In performance training, we are intentionally stealing variability so that all resources can be pushed towards raising an output (3). This always comes with a cost.
Axial Skeleton Archetypes
The two axial skeleton archetypes describe the shape of the spine, thorax and pelvis. Each of us fall into one of two broad categories: wide infrasternal angle (ISA) or narrow infrasternal angle. The ISA can also be asymmetrical, but typically we are biased towards one end of the spectrum. We cannot change a wide ISA to a narrow ISA and vice versa; however, we can encourage positions and strategies in order to optimize dynamic movement.
This measure tells us about the position and movement of the diaphragm and the structure of the ventral cavity. Our breathing strategies will dictate the position of the axial skeleton and pelvis, which impacts the position of all peripheral structures. Based on the fractal approach discussed previously, this angle is iterated across the body and is therefore a proxy measure for the geometry of the system as a whole. Each archetype has a loss of variability in certain directions, which gives us a target for exercise selection. These shapes can also provide reasoning for how someone moves in rehabilitation and performance settings. Please see this video if you’re interested in learning how to assess the ISA.
It is important to note that this is just one measure – it provides a general guideline only. Each of us will present with a variety of movement limitations based on our genetic structure, movement behaviors, previous injuries, surgeries, psychosocial-emotional profile etc. This is why we must take a detailed history and assess based on the individual at hand.
Biomechanics of Breathing
The archetypes are based on genetic structure and the need to breathe in order to sustain life. Movement health is expressed through a full excursion of breathing and normal relative-motion between joints. In order to understand these shapes, we need to understand the mechanics of breathing first.
Key: ER = external rotation, IR = internal rotation, flex = flexion, ext = extension, UR = upward rotation, ISA = infrasternal angle, IPA = infrapubic angle, ASIS = anterior superior iliac spine, SL = single leg, uni = unilateral, BB = barbell, KB = kettlebell, GHR = glute ham raise, RDL = Romanian deadlift, RFESS = rear foot elevated split squat, FFESS = front foot elevated split squat, DNS = Dynamic Neuromuscular Stabilization
Exhalation PHASE of breathing (3)(4):
Spine flattening/extension + sacral nutation
Global IR (ex. scapula UR + inominates extend/adduct/IR).
Respiratory diaphragm (eccentrically oriented) and pelvic diaphragm (concentrically oriented) ascend.
Narrowing of ISA, widening of IPA (under non-compensatory circumstances). Concentrically oriented abdominals.
Decreased bucket handle/pump handle mechanics (thorax compression).
Inhalation PHASE of breathing (3)(4):
Spine flexion + sacral counter-nutation.
Global ER (ex. scapula DR + inominates flex/abduct/ER).
Respiratory diaphragm (concentrically oriented) and pelvic diaphragm (eccentrically oriented) descend.
Widening of ISA, narrowing of IPA (under non-compensatory circumstances). Eccentrically oriented abdominals.
Increased bucket handle/pump handle mechanics (thorax expansion).
A geodesic dome with triangles as its sub-units — the entire structure compresses with exhalation (left) and expands with inhalation (right), much like the human body.
Archetypes – Biomechanics and Shape
Wide ISA/IPA (>90 deg):
Exhalation SPINE archetype. Compensatory inhalation strategy. COMPRESSION biased. (3)(4)
Spine flattening/extension + sacral nutation. Pump handle/bucket handle open.
Wide lateral dimensions, narrow anterior-posterior dimensions.
Typically limited in flexion/abduction/ER measures due to posterior compression.
Wide ISA caused by compensatory inhalation strategy: diaphragm ascended, unable to descend → have to open/widen ISA using the abdominals (eccentric orientation) in order to descend the diaphragm.
Narrow ISA/IPA (<90 deg):
Inhalation SPINE archetype. Compensatory exhalation strategy. EXPANSION biased. (3)(4)
Spine flexion + sacral counter-nutation. Pump handle/bucket handle closed.
Narrow lateral dimensions, wide anterior-posterior dimensions.
Typically limited in extension/adduction/IR measures due to anterior compression.
Narrow ISA caused by compensatory exhalation strategy: diaphragm descended, unable to ascend → have to close/narrow ISA using the abdominals (concentric orientation) in order to ascend the diaphragm.
Wide ISA (left) and Narrow ISA (right). The first two pictures are from an anterior-posterior view (front) and the second two pictures are from a superior-inferior view (top).
All of the angles are affected as the shape changes. This is a simplified representation of fractal geometry in the body.
Positional Breathing Drills
Positional breathing drills are static exercises that require focused respiration. The purpose is to shift air into compressed areas in the thorax and normalize pressures within the ventral cavity. Another intent is to inhibit overactive and facilitate underactive chains of muscles. The hope is that we can improve axial and peripheral variability by using the appropriate positions and strategies. I have included video links to some of the exercises and the rest can be found on youtube.
It is important to note that a good assessment is always the starting point – assessment guides our treatment. This isn’t the focus of today’s article, but the Postural Restoration Institute, Bill Hartman and Zac Cupples have some great material on how to assess and treat using this model. The above groups use typical range-of-motion measures (ex. adduction drop/Obers test, hip flexion, shoulder IR, cervical rotation) but the interpretation of these tests is different then what is taught in standard orthopedic circles. When looking through this perspective, these tests provide proxy measures for the position of the axial skeleton. They can also indicate what areas of the body may be compressed or expanded.
General rules:
ER measures = flexion, abduction, traditional external rotation
IR measures = extension, adduction, traditional internal rotation
Incline/decline vs. horizontal reaches: anterior reaches within certain zones either promote ER or IR based on the principles of PNF (D1/D2) and the osteokinematics of the joint.
Abduction vs. adduction: use either strategy to promote muscular activity in the direction of limitation; used to create shape change through tonal mechanisms and pressure gradients.
Positions: driving shape change through the effect of gravity on external (ex. bones, myofascia) and internal (ex. internal organs) structures.
Treatment Hierarchy:
A systematic approach using an A-B-A single subject design to determine the effectiveness of an intervention. The hope is that primary exercises will domino and correct secondary/tertiary compensations. If not, continue with subsequent strategy.
Each individual will present with a variety of limitations in ER/IR measures. Below are two archetypal representations that should be used as a guide – we still need to respect the reality of N=1. Trust your tests and put into positions based on proxy measures, limitations and overall picture.
WIDE STATIC ISA:
We want a dynamic ISA; closure of ISA upon exhale/pump handle.
Principles: drive posterior expansion. Incline or decline reaches (ER biased). Band at knees/hands to promote abduction and closure of ISA/IPA. (3)(4)
Breath: full/forceful exhalation (“blowing out birthday candles”) → 3 second pause → silent inhale without losing position. (3)(4)
Positions: side lying or inverted (driving shape change through lateral compression). (3)(4)
Side-lying exercises: left side-lying right glute max, left side-lying Hruska hip abduction, right side-lying left adductor pullback, side-lying hip shift with D2, right oblique sit with left arm reach
Supine inversion: 90/90 bridge with low reach, supine cross-connect
DNS exercises:
DNS oblique bridge → DNS shinbox getup → SB lateral split squat
DNS shoulder crowbar → shoulder driven side-plank rolls → downdog toe taps
Deadbug to DNS oblique bridge
NARROW STATIC ISA:
We want a dynamic ISA; opening of ISA upon inhale/bucket handle.
Principles: drive anterior expansion. Horizontal reaches (IR biased). Squeeze knees/hands to promote adduction and opening of ISA/IPA. (3)(4)
Breath: full/quiet exhalation (“fogging up glass”) → 3 second pause → silent inhale without losing position. (3)(4)
Positions: supine or quadruped (driving shape change through AP compression). (3)(4)
Quadruped exercises: diamond bear, modified all four belly lift, rockback variations
Supine exercises: 90/90 hip lift variations with reach and squeeze, crook lying reach and squeeze
WIDE DYNAMIC ISA:
Once dynamics of ISA restored, inhalation biased (FLEX/ER) activities.
Limited ER measures? Need dorsal rostral expansion
Positions: inversion based activities or activities with incline/decline reaches
Inverted exercises: 90/90 bridge with low reach, inversion off GHR, knee-to-chest headstand, prone breathing with airex at ASIS, toe touch progression
Reaches at top/bottom of plane: seated elbows on table with ER, sink squat → wall squat with reach (with or w/o chair) → resisted wall squat with reach, TRX respiratory squat, ski slope squat
NARROW DYNAMIC ISA:
Once dynamics of ISA restored, exhalation biased (EXT/IR) activities.
Limited IR measures? Need pump handle mechanics/anterior expansion
Positions: supine or quadruped activities
Quadruped exercises: diamond bear, modified all four belly lift, rockback variations
Supine exercises: 90/90 hip lift variations with reach and squeeze, crook lying reach and squeeze
Other: crab hold with heel dig, supported squat hang
DNS exercises:
3 month prone → rockback hip extension → quadruped to downdog
Strength Training
I’m a big believer in using challenging loads during rehabilitation. We should strive to use higher threshold activities if we wish to make sustained changes. Adequate load may be required for stronger patients who need more stimulus to create change. Keep in mind that near maximal loads may actually interfere with the restoration of movement variability. A balance between force production and relative motion is what we are aiming for.
Other favorable outcomes to loading shouldn’t be ignored, like mechanotransduction, desensitization, and strengthening. However, we can also reap the benefits of improved variability if we use a test-retest approach and apply the right exercises. We can do this by manipulating the movements, planes, and vectors which are guided by our assessment. The art of Physical Therapy is how we coach these exercises. Different strategies should be taught based on the physics of the individual and the desired outcome.
General rules:
Squats = inhalation mechanics (spine flexion + sacral counter-nutation + inominate flex/abduct/ER)
Hinges = exhalation mechanics (spine flattening/extension + sacral nutation + inominate ext/adduct/IR)
Incline/decline presses and pulls = bias ER mechanics (flexion/abduction/ER)
Horizontal presses and pulls = bias IR mechanics (extension/adduction/IR)
WIDE ISA:
Principles – incline or decline presses and pulls (ER biased). Band at knees/hands to promote abduction and closure of ISA/IPA. Unilateral exercises when possible, especially for upper extremity (promote reciprocation and alternating compression/expansion)
Bilateral squat progressions – reaching ramp squat → goblet squat → zercher squat → front squat
Unilateral squat progressions – shifted ramp squat → FFESS → knee dominant step-up → SL box elevated squat
Lateral squat variations – landmine lateral skater squat → goblet lateral lunge
Incline or decline pulls – split stance low-to-high uni row, ½ kneeling high-to-low uni row, deep squat high-to-low alternating row, alternating chest supported row
Incline or decline pushes – landmine press variations, alternating incline press, alternating bridge press, split stance decline uni press, decline staggered push-ups
Cable chop variations – tall kneeling chop → ½ kneeling chop → split stance chop
Anti-lateral flexion variations – side-plank variations, suitcase marches, arm bar variations, pallof press, vertical pallof press (frontal plane)
Flexion rolling – eggshell, backward rolls, segmental roll supine to prone
Arms – pronated bicep curl in shoulder ER, pronated triceps extension in shoulder ER
Locomotion: lateral sled drag, suitcase/farmers carry → rack carry → waiters carry
NARROW ISA:
Principles – horizontal presses and pulls (IR biased). Squeeze knees/hands to promote adduction and opening of ISA/IPA. Unilateral or bilateral exercises.
Squat progressions – box squat → hip dominant back squat → hip dominant step-up → RFESS
Bilateral hinge progressions – DB RDL → snatch grip RDL → BB RDL → KB deadlift → trap bar deadlift → BB deadlift
Unilateral hinge progressions – Campo deadlift → kickstand RDL → SL RDL
Horizontal pulls – split stance uni row, 3 point row, renegade row, inverted row, face-pulls
Horizontal presses – split stance uni press, push-up variations, floor press, DB press
Long lever chest/back work – DB fly, I/T/Y variations
Cable lift variations – tall kneeling lift → ½ kneeling lift → split stance lift
Anti-extension variations – plank variations, ab rollout variations, deadbug variations, hollow holds, pullover variations
Extension rolling – forward rolls, segmental roll prone to supine
Arms – supinated curl in shoulder IR, supinated triceps extension in shoulder IR
Locomotion: reverse sled drags, bear crawl variations, crab crawl variations, suitcase carry → bottoms-up carry
Thanks for staying with me until the end! If there are any questions or if I was unclear in my explanations, please feel free to reach out. On a separate note, I’m posting a lot on my Instagram these days, so please follow me over there. Subscribe to my newsletter as well for future updates!
References:
1. Hamill J, Palmer C, Van Emmerik R. Coordinative variability and overuse injury. Sports Medicine, Arthroscopy, Rehabilitation, Therapy & Technology. 2012;4(1).
2. Stergiou N, Decker L. Human movement variability, nonlinear dynamics, and pathology: Is there a connection?. Human Movement Science. 2011;30(5):869-888.
3. Hartman B. The Intensive IX. Presentation presented at IFAST; 2019.
4. Cupples Z. Human Matrix: The Code for Maximal Health and Performance. 2019.
5. Postural Restoration Institute; Postural Respiration, Pelvis Restoration. 2019.