
Reasons to Love The Lateral Line
There are many reasons to love both working and stretching the lateral line of the side body. One of the main reasons being, that most of us live a good portion of our waking lives in the sagittal plane of flexion and extension.
Too much flexion compresses the ribs affecting the natural curves of our spines and in some cases pushes spinal discs out of alignment and can even impinge the nerves found in the spine which protects our central nervous system! A weak and often tight lateral line compromises our stability causing lack of support effecting activities like your golf swing!!!
Transitioning out of the Sagittal Plane
Strengthening the Lateral Line
When working the lateral line, adding spring-based load to one side, fires the core to stabilize against it. Having a strong trunk or core is essential to balance, and strength for single leg functional activities like walking, hiking, biking that require us to balance on one leg 40% of the gait strike. Adding the lateral load with standing based Pilates repertoire, builds strength against gravity, mimicking these every day life activities!
Standing single arm loaded squats with one strap around your shoulder on the reformer, fires the low back and spinal erector muscles on one side of your body and forces your core to engage building strength on that side. Executing this movement in both directions facing the foot bar and then the tower changes where the load comes from as well.

Stretching The Lateral Line
Simply put stretching laterally pleases the systems of the body by transitioning out of the sagittal, habitual plane of movement. When we expand out of the sagittal plane into the coronal plane, which is the anatomical plane of dividing the body into front and back where lateral flexion takes place with side bending, we help maintain the natural curves of our spine that is aligned.
A spine that is strong and aligned allows the weight of the body to travel through the center of our joints…read that last line one more time, as it is the whole point to being balanced and avoiding injury or pain!

Muscles are both Stretched + Strengthened in Lateral Flexion
A benefit to stretching laterally is that one side stretches and the other supports. In lateral flexion, there are major muscles on one side of the body working (agonist) and major muscles stretching (antagonist) on the other. In finding your “side lines” of movement, the deeper spinal muscles are more active and efficient during side bending/lateral flexion than the abdominal muscles but both are engaged as you’ll see below.
Lateral flexion postures and exercises such as Mermaid and Side Plank on the mat and chair, Short Box lateral flexion series on the reformer and Extended Side Angle in yoga strengthen and lengthen the following main muscles in our front + back body:
- Quadratus Lumborum (QL)
- QL is a deep low back postural muscle that flexes the spine laterally, originating from transverse processes of L1-4 and Rib 12 and inserts to the posterior (back) portion of the Iliac Crest (pelvis);
- Internal and External Obliques
- Are located at the sides of your abs (pubic bone to lower and mid-ribs). They are synergists in helping the QL with lateral flexion along with our spinal erectors and Latissimus Dorsi especially with an over hand reach in certain exercises mimicking some sport-related movements like tennis or racquet ball;
- Erector Spinae,
- the muscles that run along the spine itself;
- Sternocleidomastoid neck muscle,
- one of the largest superficial muscles of the neck involving bending the head to one side, which also stretches the levator scapulae, at the side and back of the neck which elevates the shoulders, and erectors in the cervical spine;
- Latissimus Dorsi
- Is the largest/broadest muscle of the back, originating from the mid-back to the lower/lumbar spine (T7 – L5) and bottom ¾ of the ribs inserting into the medial humerus. The “Lats” primary job is to take the arm from an overhead position (when we add the arm in “Side Angle” or “Mermaid” and draw it down towards your side body which we cue in Pilates as “setting the shoulder”.
How Deep Should we stretch laterally?
The normal range of motion for the cervical spine is 45 degrees of lateral flexion and the lumbar spine or low back has 25 degrees of lateral flexion.
Lateral flexion also opens up and affects much more than just muscles. In addition to feeling taller and lighter, it is important to mention some of the immense benefits of other systems of the body that benefit from side stretching and strengthening as below:
- Respiration with the expansion of the intercostals (ribs) stretching allowing for a full breath
- Digestion
- Lymphatic systems
- Endocrine systems
- the collection of glands that produce hormones that regulate metabolism, growth, tissue function, reproduction, sleep and mood.
The Long + Short for Love on the Side Lines
So “Loving” your side lines in lateral flexion in all its forms and exercises both work and stretch your spine and muscles simultaneously from side to side.
Bottom line though, is that it just feels GREAT to do this movement. Your spine thanks you as you move in this new direction, your low back (QL) thanks you as it is stretched and strengthened and your lungs thank you as you decompress your ribs you can breathe fully!
