WELCOME TO the MONTHLY THROUGH LINE

Hey Chromatic family,

This month we’re going to the center of the system, THE SPINE. Every arm balance, every twist, every forward fold and backbend is, at its root, a spinal story, and understanding that story is what separates a teacher who cues “arch your back” from one who can actually explain what’s happening, why, and how to make it feel good.

The spine is organized into five regions, cervical (7 vertebrae), thoracic (12), lumbar (5), sacrum, and coccyx. Each region has a different job, the cervical and lumbar spine are built for mobility, the thoracic spine (anchored by the rib cage) trades some mobility for stability, and the sacrum and coccyx are largely fused, transferring load down into the pelvis and legs. 

The spine’s curves are what make it strong. A perfectly straight column of 24 stacked vertebrae would be structurally unstable under load. But the spine’s natural S-curve, cervical lordosis, thoracic kyphosis, lumbar lordosis, acts like a spring, giving it dramatically more resistance to buckling and compressive force than a straight rod ever could. Those curves aren’t a flaw to “correct,” they’re the architecture that lets the spine hold you upright all day and absorb shock without breaking down.

Your discs get nutrtion through movement. The intervertebral discs have almost no direct blood supply. They get their hydration and nutrients through imbibition, a pumping action driven by changing pressure as you move, flex, extend, and breathe. A sedentary spine isn’t just “stiff,” it’s under-nourished or starving. Movement is quite literally food for the vertebral column.

This month we’re breaking the spine down into its four fundamental actions, one per week, extension, flexion, rotation, and lateral flexion. Let’s get into it.

For the newcomers to the CHROMATIC MONTHLY THROUGH LINE: In Chromatic Yoga, we like to keep things straightforward. This “Monthly Through Line” is a community initiative designed to help our Chromatic Teachers focus and intelligently design classes to best support your students. If you’re not a Chromatic Teacher yet, and are simply here out of interest, that’s great too, as you might want to find and attend a Chromatic Class in person or online and feel what its like to apply these through-lines to gain more insight in to body biomechanics and potentially access the poses in a deeper and more intelligent way.

WHAT IS A PHYSICAL THROUGH LINE? 

• A Physical Through Line is a term we use in Chromatic Yoga that is defined by the muscle engagement (e.g. engaging the glutes in Warrior 3), or the joint action (e.g. back extension in Camel) that we focus on through the duration of the yoga class. Certified Chromatic Teachers construct their classes around a PTL (Physical Through Line) in order to create a more effective learning environment for students. As a student you can expect that each Chromatic class will include a PTL. Of course, you will do other postures and other muscle engagements within a Chromatic class, however there is a strong emphasis on the PTL. 

Week 1: EXTENSION – real longevity for your body 

What It Is: In yoga, extension is often mistaken for “backbending,” but it’s far more nuanced and intelligent than simply throwing the body backward in space. Spinal extension is the lengthening and straightening of the vertebral column, drawing it into a taller, more upright, or backward-curving shape. And it isn’t the spine’s job alone, the legs (hips, knees), arms, and shoulders all participate in a well-organized extension pattern 

Key Muscles: Erector spinae, multifidi, deep core stabilizers, trapezius, and latissimus dorsi all contribute to extending and supporting the spine through its length.

Why It Matters: Most of us spend the majority of our day folded forward, seated, typing, driving, scrolling, collapsing into flexion-dominant patterns that gradually narrow our available movement options. Over time, many bodies lose not just mobility into extension, but strength, coordination, and confidence there too. Learning to extend safely transfers directly into daily life and is a real marker of long-term vitality, every time you lift your chest, look up, stand upright, or resist collapsing under load, your spinal extensors are doing the work. The goal isn’t a deeper backbend, it’s a more responsive, articulate, functional spine. Think length and lift, not just bend.  

Where it shows up: Cobra, Upward-Facing Dog, Locust (Salabhasana), Bridge, Bow, Wild Thing and Camel (Ustrasana) all draw on organized spinal extension, creating space between vertebrae, engaging the erector spinae, and using the breath to lift and expand from within, rather than compressing into the low back.

Week 2: Flexion – More than just a foward fold

What It Is: Spinal flexion is the action of rounding the spine, bringing the head, shoulders, and rib cage closer to the pelvis. 

Key Muscles:  Rectus abdominus, external and internal obliques contracting bilaterally and psoas.

Why It Matters: While we often think of this as “forward folding,” true spinal flexion involves segmental movement, especially in the cervical, thoracic and lumbar regions. It’s essential for developing core strength, awareness, and safe transitions. And simply in life when we bend over to tie our shoes. It also plays a huge role breath control as it influences diaphragm excursion and rib mobility. Just as we talked about extension being underused in our forward-folded, desk-bound lives, the flip side is true too, for many bodies, the muscles required for active flexion are weak, underused, and chronically short rather than strong. Building genuine, engaged flexion, not just passive collapse, is just as fundamental.  

Where it shows up: Balasana Childs Pose, Ananda Balasana Happy Baby, Cat, Uttanasana Standing Forward Fold, Bakasana Crow Pose, Pachimottanasana Seated Forward Fold.

Week 3: ROTATION – Find the energy in the twist

What It Is: Structurally, rotation happens when one vertebra turns relative to the one above or below it, most freely in the thoracic spine. In the asana practice it is when one side of the trunk twists forward whilst the other twists backward. True spinal rotation begins with establishing a foundation (think anchor point), then length, by lifting through the crown and broadening the chest first, to avoid the vertebrae spiral without compressing into one another.

Key Muscles: The obliques (working asymmetrically this time, rather than bilaterally as in flexion), along with the deep rotatores and multifidi, drive and stabilize the twist segment by segment. Rectus abdominus assist in stabilising twists. If we really get geeky, rhomboids and latissimus dorsi also play a part in retracting the scapular in twists. 

Why It Matters: The spine is built for both stability and mobility, and rotation is one of its most expressive movements. Healthy rotational capacity improves circulation, supports joint health, balances opposing muscle groups, and expands overall range of motion. Without it, the body stiffens, breath becomes shallow, and mobility across the whole system is compromised. Spinal rotation also creates space for deeper breathing and releases muscular tension along the entire column.

A few key principles for healthy spinal rotation, worth cueing directly to students, lift before you twist, lengthen the spine upward first, twist evenly, distribute the spiral across the thoracic spine, not just the lumbar, lead with breath, exhale to rotate deeper, inhale to create more space, ease, not force, avoid yanking or cranking with the hands, elbows, or arms, let the spine rotate naturally.

Where it shows up: Seated Twist (Ardha Matsyendrasana), Revolved Triangle, Revolved Chair, and supine twists. This week, notice how lifting before you twist transforms the whole experience of rotation, whether you’re seated, standing, or lying supine.

Week 4: LATERAL Flexion – an often left out Movement

What It Is: Lateral flexion is side-bending of the spine, the ear moving toward the shoulder, the rib cage shifting laterally, think taking the shoulder to the hip, one side of the torso lengthening while the other side shortens. It’s the plane of movement most yoga practices touch least, and the one most bodies have the least awareness of.

Key Muscles: Quadratus lumborum and the internal and external obliques (working unilaterally this time) initiate and control the side bend, with the intercostal muscles lengthening and shortening between the ribs on either side.

Why It Matters: Lateral flexion is the quiet action, it doesn’t announce itself the way a backbend or a twist does, which is exactly why it tends to get neglected in practice and in daily life. Habitual asymmetries (carrying a bag on one shoulder, favoring one side at a desk, always sleeping on the same side) create imbalances between the two sides of the torso that rarely get addressed unless we deliberately train side-bending in both directions. Practicing lateral flexion improves rib mobility and breathing capacity on each side individually, not just the front and back of the ribcage, builds proprioceptive awareness in an underused plane, and helps restore symmetry to a spine that spends most of its life moving only forward, backward, and occasionally twisting. 

Where it shows up: Half Moon (Ardha Chandrasana) in its side-bending variations, Gate Pose (Parighasana), Extended Side Angle (Utthita Parsvakonasana), and Crescent Moon side-bend all train lateral flexion, each one asking you to lengthen one side body while the other side contracts to support the bend.

Simon’s RECAP AND TIPS

I personally love the actions and engagements of the spine. In particular rotation (twists) are one of my favorite and now I love spinal extension hugely although I used to really avoid deep backbends because of how “lombar compressive” they were for me. That was until I did a heart opening (back-bending) workshop with Matt in Sweden years ago. Having someone speak the same language of anatomy and biomechanics gave me the mental understanding I needed, however the breath through was the intelligent layering of poses, and the step by step explanation of “feeling” what the spine did in each, leading up to the peak pose (full Wheel no less) that allowed me to go not just further, but safer, more open, and totally unlocked access to my spine in a way that I had never been able to prior. 

Once we understand how to create space in the vertebral column, using the breath to lift and expand, rib positioning, abdominal support, and thoracic mobility, and understand the muscles doing the work (erector spinae, multifidi, deep core stabilizers, trapezius, latissimus dorsi, and more), spinal movement starts to feel expansive rather than compressive. It’s an organized distribution of movement throughout the entire column, not one segment doing all the work.

Now for the wow factor and the anatomy and physiologogy nerds out there! The spine isn’t just an architecture, it’s a switchboard. Thirty-one pairs of spinal nerves branch out from the cord between the vertebrae, and every one of them exits through a tiny gap called an intervertebral foramen, a space that changes shape with every single movement the spine makes. Flex it, and that space opens. Extend it, rotate it, side-bend it, and it opens and closes differently on each side, at each level. This means every posture we teach isn’t just shaping muscle and bone, it’s actively changing the room available for the nerves that innervate the arms, the organs, the legs, the diaphragm, essentially the entire body. The phrenic nerve that drives your breath originates as high as the cervical spine. The nerves that fire your hamstrings and control your bladder exit down in the lumbar and sacral spine. There is no muscle, no organ, and no sensation in the body that isn’t, at some point, a spinal story first.

Movement isn’t only biomechanical, it’s neurological. When we cue a student into a well-organized extension or a segmental rotation, we aren’t just engaging or lengthening tissue, we’re actively changing the neural real estate available at every level of the cord. A spine that moves through its full range in all four directions is a spine that is, quite literally, keeping every channel of communication between brain and body open and unobstructed. That’s the real depth behind “the spine is the center of the system,” it isn’t a metaphor, it’s neuroanatomy.

Chromatic Yoga is a global community. No matter where you are in the world, we hope you’ll join us this month for a deep dive into the huge possibilities in the joint actions and associated muscle engagements related to moving one of the most important parts of our body. Share/tag/collaborate your poses on Instagram. 

 Wishing you an intentional and transformative practice in the month ahead, 

~Simon Darroch

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