In “Preventative Strategies for Lower Back Strains Part I,” we discussed femoral-pelvic and lumbar-pelvic rhythm, muscles that influence these rhythms, and the effects of these muscles on the lumbar spine. Here, our discussion progresses as we cover the trunk, the thoraco-lumbar fascia (TLF), Uddiyana Bandha and how accurate knowledge of this can be used to enhance the benefits of yoga and decrease the risk of lower back strains.
The thoraco-lumbar complex (TLC) is a multilayered structure comprised of the thoracolumbar fascia and the muscles that connect to it. This composition of passive fascial tissues and active muscular structures acts as a corset-like structure that encircles the torso. It plays a key role in maintaining the integrity and stability of the lumbar spine and the sacroiliac joint and is also important for load transfer from the upper limbs to the lower limbs.
Engaging the muscles that connect to the thoracolumbar fascia acts to stabilize the spine and trunk. We give an example of this in a previous blog post on using the latissimus dorsi to lift the lumbar and expand the thorax. Figure 1 illustrates the thoraco-lumbar composite in cross section at the mid-lumbar.
To further illustrate, consider a cylindrical container of a fixed volume. Decreasing the circumference of the cylinder results in an increase of its’ length (to maintain the total volume). The torso, with the abdominal cavity, can be viewed in the same manner: tensioning the abdominals acts in combination with the TLF to lengthen the torso and lift and stabilize the lumbar. Think of this concept in conjunction with the Sanskrit term “Uddiyana,” which means lifting or flying up. Figure 2 illustrates this.
The mechanism for lengthening the trunk with the thoracolumbar complex. The pelvic diaphragm is below and the thoracic diaphragm above.
This lengthening of the torso takes place through several mechanisms that work in concert to variable degrees depending on the position of the trunk. The first action relates to intra-abdominal pressure (IAP). Engaging the abdominals increases IAP, which numerous scientific studies have indicated stabilizes the lumbar spine.
The second mechanism relates to tensioning the TLF. Activating the transversus abdominis muscle tensions the TLF, thereby providing resistance to flexion at the lumbar spine. Furthermore, the transversus abdominis muscle has attachments to the thorax; engaging it transfers stresses from the lumbar region to the thorax and shoulders.
Tensioning the TLF also improves the efficiency of the back muscles (surrounded by this fascia) through a mechanism known as the hydraulic amplifier. Because the erector spinae are surrounded by the TLF, its various layers resist muscle expansion during contraction.
This tends to straighten the spine (think of how a bicycle tire straightens when you fill it with air). Finally, the erector spinae muscles have fibers that insert onto the interior surface of the TLF so that as they lengthen into a stretch, they can exert a passive pull on the fascia. These various mechanisms contribute to lengthening the torso and stabilizing the lumbar spine. I provide a number of scientific references on this subject below.
Clinical studies have demonstrated an association between low back pain and inefficient engagement of the abdominals. All of this has implications for the use of Uddiyana Bandha, both for protecting against low back strains and for potentially improving the treatment of low back pain through yoga. Below, we illustrate the sequence I use to access this mechanism.
Ease in to awareness of the thoracolumbar composite by using a progression of poses. This leads to understanding of the action of Uddiyana Bandha in lifting and lengthening the trunk and stabilizing the spine.
Begin with a pose like simple crossed legs (Sukhasana) or Dandasana. The cue for co-activating the abdominal core and erector spinae is to draw the navel towards the lumbar and lift the lower back. Visualizing the trunk as an hourglass and the anatomy of the thoracolumbar composite as a corset helps to access this lifting and lengthening action.
Fixing the hands on the mat and attempting to drag them backwards accentuates this lift by including the latissimus dorsi. Incorporating the accessory muscles of breathing, including the pectoralis minor and serratus anterior, in this pose lifts the lumbar from the thorax. You can experience this lengthening effect by initiating these cues even as you sit reading this post.
After warming up, incorporate these same principles into Downward Facing Dog Pose. Engage the thoracolumbar composite by co-activating Uddiyana Bandha and the erector spinae (and quadratus lumborum) to lengthen the trunk and to lift the tailbone, respectively. (Figure 4)
These same protective mechanisms can be accessed in forward bends such as Paschimottanasana by using the abdominals to lengthen the trunk, as with the hour-glass visualization described above. Additionally, engaging the abdominal core aids in accessing the function of these poses, which is reflected by their form. Part of this function is to lengthen the muscles of the back. Engaging the abdominal core helps to relax the erector spinae through reciprocal inhibition.
Peripheral fibers of the erector spinae attach to the TLF; as these muscles lengthen, their fibers exert a pull on the TLF, thus distributing the forces through the length of the spine. Accordingly, although I may use brief periods of contraction to release the muscle (through PNF), I do not recommend maintaining eccentric contraction of the erector spinae throughout the pose (I will explain why in the next blog post).
I combine the actions of the thoracolumbar complex with lumbar-pelvic rhythm by engaging the muscles that contribute to tilting the pelvis forward. Figure 5 illustrates the connection between the tensor fascia lata, the pelvis, and the thoracolumbar composite. See “Preventative Strategies for Lower Back Strains, Part II” for the cues on engaging the synergists of hip flexion and forward pelvic tilt. Also see our post on co-activating the gluts and abs in Chaturanga Dandasana.
The anatomy and protective mechanisms of the human body have evolved for eons. These same mechanisms have been researched and documented in the scientific literature. Anatomic and biomechanical principles that govern our bodies when we perform simple actions, such as walking, also apply when we are on the mat. Keeping this in mind, we must dispose of some incorrect concepts permeating the yoga world concerning anatomy and how the body works.
The first of these implies that engaging the abdominals and Uddiyana Bandha harms the intervertebral discs. This misinformation, often circulated with graphic descriptions of lumbar disc herniations, discourages engaging the protective and stabilizing mechanisms of the thoraco-lumbar complex in yoga poses under the misguided premise that avoiding these essential mechanisms somehow protects an individual.
Other disinformation discourages engaging the abdominal core in forward bends under the odd premise that contracting these muscles causes “congestion”. Finally, there is the breathtaking statement that the spine does not depend on muscles for stability. This widely circulated misconception is contradicted by basic anatomy and yoga itself. In this regard, I quote Jiddu Krishnamurti: “Until the false is seen as the false, truth is not.”
Good to see you again. Practice under the guidance of a qualified instructor; use their assistance to determine modifications or suitability of a given pose for your individual practice. Always consult your healthcare provider and obtain medical clearance before practicing yoga or any other exercise program.
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