Hey there reader! Let's get twisted! Haha, JK! But for realsies, let's chat about the spine for a bit.
The spine can move in several ways, including flexion (i.e. anterior surface of the body comes closer together), extension (i.e. posterior surface of the body comes closer together), lateral bending (i.e. side bending), and rotation (i.e. turning/twisting). In this blog post, I will discuss spinal rotation from a general sense, including the main muscles that control rotation and some of the benefits of spinal rotation. Different segments of the spine can rotate independently of the other segments (e.g. cervical, or neck, rotation only), but a discussion of spinal rotation in each spinal segment is outside the scope of this post.
The vertebral column, or spine, of an adult human is composed of 33 bones. Of these 33 bones, 24 are known as articulating, or movable, vertebrae, separated from each other by an intervertebral disc. Spinal rotation is a spinal movement in which you turn the spinal column around itself. Basically, in spinal rotation, you are turning your trunk around an axis, in which the spine is the axis. Essentially, when you are twisting (aka rotating), your shoulder girdle moves to face the opposite direction in relation to your hips.
What Muscles are Responsible for Spinal Rotation?
While there are certainly many muscles that assist in some way to produce spinal rotation, this blog post will highlight the "main players" - i.e. the External and Internal Obliques, Multifidi, and Rotatores. These "main players" have several functions, or actions, that they produce. However, for the purpose of this blog post, I will discuss the role they play for spinal rotation only.
External Obliques
The External Oblique, one of the four abdominal muscles, is lateral (i.e. to the side) of the Rectus Abdominis (i.e. the "6-pack muscle" on the front of the abdominals). The External Oblique is a broad, superficial (i.e. closer to the surface of the skin) muscle. Regarding spinal rotation, the External Oblique, working unilaterally (i.e. only one side engaged at a time) rotates the vertebral column to the opposite side.
Internal obliques
The Internal Oblique, also one of the four abdominal muscles, is deep (i.e. further from the surface of the skin) and perpendicular to the External Oblique. Regarding spinal rotation, the Internal Oblique, working unilaterally, rotates the vertebral column to the same side.
Multifidi and Rotatores
The Multifidi and Rotatores are spinal muscles that extend the length of the vertebral column. The Multifidi and Rotatores consist of many short, diagonal fibers. These fibers form an intricate, stitchlike design that links the vertebrae together. The Multifidi are superficial to the Rotatores and can span two to four vertebrae in length. The Rotatores lie deep to the Multifidi and can span one to two vertebrae in length. Regarding spinal rotation, both muscle groups, working unilaterally, to rotate the vertebral column to the opposite side.
What are the Benefits of Spinal Rotation?
Movements that involve spinal rotation can lead to improvements with:
Vestibular system functioning
Digestion
Range of motion in your core
Core strength
Balanced core strength
Vestibular System Functioning
The vestibular system, found in your inner ear, is a sensory system that is responsible for providing your brain with information about motion, head position, and spatial orientation. The vestibular system uses information obtained in the inner ear to maintain balance, stability, and posture. Thus, the vestibular system is essential for normal movement and equilibrium. Disruption of the vestibular system can lead to symptoms such as vertigo, loss of balance, and nausea. Vestibular exercises, such as spinal rotation, may help to improve vestibular system functioning.
Digestion
When you engage in a twist, or spinal rotation, you essentially compress your abdominal organs (e.g small/large intestines, liver, stomach, etc.). Yogic philosophy suggests that this compression can reduce blood flow to the abdominal organs. And when you release the twist, there would theoretically be a rush of "fresh" blood to these organs. This "fresh" blood contains oxygen and other chemicals that nourish the cells in your abdomen. The increased circulation to these cells also helps to remove cellular waste products (e.g. carbon dioxide). The combination of increased nutrient delivery and waste removal allows these cells to function at their optimal levels, ultimately making you feel better and healthier in your digestive system.
Range of Motion in your Trunk
When you take a joint through its full range of motion, it can improve flexibility and strength of the muscles involved in moving that joint AND mobility of the joint itself. Movement at a joint can also improve circulation of the fluids within that joint, getting rid of cellular waste and bringing in new materials for those joint cells to use. Your spine contains 24 articulating, or movable, vertebrae. These movable vertebrae articulate with a nearby vertebrae to form what is known as a facet joint, a type of synovial joint (i.e. it contains synovial fluid in the joint area). When you move your spine through rotation, you help to take each individual facet joint through its range of motion. This action helps to improve flexibility and strength in the muscles that produce rotation. It also helps to improve mobility (i.e. the ease and degree of movement in the joint) of these facet joints. When the muscles that produce rotation are flexible and strong, it can lead to better breathing mechanics, posture, and movement in your body.
Core Strength
Your core is the foundation for virtually all movements in your body. When your core is strong and stable, it allows the rest of your body to move more safely and efficiently. A weak core can lead to poor posture and even back pain or injuries. Core muscles provide a base of support for the entire body. Your core supports your spine and pelvis and connects your upper body to your lower body, effectively transferring forces from one to the other. A weak core can lead to injuries elsewhere in your body. Spinal rotation exercises help to strengthen some of your core muscles (e.g. obliques, some spinal muscles), since rotation of the spine is achieved by contraction of these core muscles.
Balanced Core Strength
If the muscles on one side of your body are stronger than the opposing side, it can disrupt the natural range of motion of that particular joint, potentially leading to injury. Spinal rotation exercises should always be completed on both sides of your body - left AND right. This action can help to re-balance core strength in your oblique muscles and some spinal muscles, allowing your core to move in a more natural way. When your core moves more naturally, you are less likely to get injured, experience pain, or have performance issues in your sports/exercise routine. Spinal rotation, when completed on both left and right sides, can help to balance, or re-balance, the muscle strength in your oblique and spinal muscles.
Summary
Spinal rotation confers many benefits to the overall functioning of your body. All of the benefits described above can ultimately lead to better breathing mechanics, posture, and overall movement in the entire body. Try to incorporate some spinal rotation throughout your day and in your exercise routine. Stay tuned for a future blog post describing different yoga poses that involve spinal rotation. Please keep in mind, the information in this post is gleaned from my own personal study and practice of yoga and movement. As always, you are ultimately your best teacher. As my trainer and mentor, Lauren Reese, M.S., E-RYT, always says, "be a student of your body." If you have any questions about adding spinal rotation to your workout routine, please consult with your physician, physical therapist, or athletic trainer. Thanks for reading!
~Namaste, Jackie Allen, M.S., M.Ed., CCC-SLP, RYT-200, RCYT
Special thanks to my husband, Matthew Allen, for doing the anatomical drawings in this post.
References:
Asher, A. (2020). "How to Develop Normal Spinal Rotation." Very Well Health. Article link here.
Biel, A. (2014). Trail Guide to the Body: "A Hands-On Guide to Locating Muscles, Bones, and More." p. 200, 210-211. Books of Discovery.
Bridwell, K. (2019). "Facet Joints of the Spine's Anatomy." Spine Universe. Article link here.
Chung, B. (n.d.) "Understanding the 5 Movements of the Spine in Yoga Asana." Do You Yoga. Article link here.
Khan S., and Chang R. (2013). Anatomy of the vestibular system: A review. NeuroRehabilitation, 32(3), 437-443
Mazzo, Lauren. (n.d.) "Why Core Strength is so Important (It has Nothing to do with Sculpting a Six-Pack)". Shape. Article link here.
Sugaya, T. et al. (2016). Relationship between spinal range of motion and trunk muscle activity during trunk rotation. Journal of Physical Therapy Science. 28(2): 589 - 595.
Washington, A. (n.d.). 5 Health Benefits of Yoga Twists. Do You Yoga. Article link here.