Posterior Pelvic Tilt Part 1: The Tail-Tuck Cue

Throughout my yoga journey, I have come to realize that certain movement cues are plagued with polarity. Take squaring your hips (e.g., Warrior 1; Janu Sirsasana, pyramid) or contracting your glutes (e.g., upward facing dog, bridge). And while I have become accustomed to understanding which cues work in my body and which cues I can politely ignore, I have greatly grappled with the tailbone tuck cue. The tail-tuck cue can be recognized by one of its many aliases — “lengthen your tailbone down”; “curl tailbone under”; “tilt your pelvis back”; “pull your front hips up”; “shorten the front side of your body” etc. You may catch wind of these cues through a vast array of asanas from mountain pose to high plank to chair pose to pretty much any backbend.

 

The debate — To tuck or not to tuck

When I began practicing yoga, I quickly noticed a wide array of opinions about how I should be positioning my pelvis in a plethora of poses. In fact, the yoga blogging community is filled with opinions about this controversial cue (see here, here, here, here, and here). Pro-tail-tuckers swear by its ability to stabilize and protect the low spine by reducing the natural lumbar curve and supposedly minimizing undue compression. Anti-tail-tuckers claim that the very same movement actually has the opposite effect. They believe that maintaining our natural lumbar curve offers our low back stability and protection from compression injury. They also claim that tucking the tailbone has other drawbacks such as stiffness in the spine, limited mobility of the surrounding structures (i.e., pelvis) and a propensity for leading to low back pain.

These are some hefty and conflicting claims. In this three-part blog series I will explore the tail-tuck cue by drawing on the scientific literature to assess how we may use it in asana. In Part 1 (today’s post) I will anatomically unpack the tailbone tuck. In Part 2, I will introduce the concept of spine stability as it relates to the tail tuck. In part 3, I will take the concepts we learned in Parts 1 & 2 to discuss how it relates to various yoga postures.

What’s in a tailbone tuck: The Posterior Pelvic Tilt

A tailbone tuck, anatomically speaking, is a posterior pelvic tilt (PPT). In Figure 1, I am performing high plank with my pelvis in three different positions: an anterior tilt (A), a neutral position (B), and a posterior tilt (C). You can see from Figure 1 C that the PPT flattens the natural (lordotic) curve in the low spine. In doing so, the PPT accomplishes another task: it encourages contraction through rectus abdominis (RA; the six pack muscle). Thus, in addition to being allegedly associated with stability of the lumbar spine (which we’ll explore in Part 2 of this series), the PPT is an effective way to encourage contraction through RA. Let’s take a closer look.

Plank 2.jpgFigure 1. Pelvic position in high plank.

Contraction Through Rectus Abdominis (RA) and the Hollow Body Form

In this short video El Eggs from Calisthenic Movement discusses how incorporating a PPT into many exercises (e.g., push-ups, pull-ups, leg-raises) is a functional way to strengthen the abdominals. The PPT requires robust activity in rectus abdominis (RA), a finding confirmed in a 2004 study looking at the muscle activity of RA during the PPT1. The tail-tuck is therefore a helpful movement if our intention is to maximize the contraction of RA while reducing the curve in the low spine. Take an example where the low spine is not weight bearing — take high plank.

 

High plank, to begin with, is a pose that strengthens many core muscles. And while there is nothing inherently wrong with practicing high plank pose with a neutral spine or anterior tilt (see Figure 1 A & B), employing a PPT allows you to recruit more RA activity. Moreover, high plank with a PPT trains the body to express another anatomical pattern that is worthwhile bringing into this discussion: the hollow body position. The hollow body position is a staple movement pattern (particularly in gymnastics) where you engage your “anterior chain” (i.e., the muscles along the front side of your body). A hollow body position requires a PPT. Training your body to maintain a hollow body position will strengthen many postures that require sufficient strength along the anterior chain. Crow pose, pictured below, is a prime example of this.

Hollow body position.jpgFigure 2. Hollow body position and crow pose.

 

PPT and Hip Extension

The PPT also has a relationship to hip extension (i.e., thigh and belly moving away from each other). The conventional list of “hip extensors” includes gluteus maximus and the hamstrings, however, RA (the PPT muscle) is functionally related. RA can increase the amount of tension placed on the hip flexors2. As RA contracts and rotates the pelvis up towards the ribs, it consequently pulls on the quadriceps muscle that originates on the pelvis, as illustrated in Figure 3, A. Let’s look at reclined hero pose as an example.

Reclined hero

In reclined hero pose, the quadriceps muscles, which flex the hip and extend the knee, are stretched because the pose requires them to express the opposite of their action — that is, hip extension and knee flexion. When you add the intention of a PPT, you contribute to the hip extension already at work and thus increase the stretch in the quadriceps muscle that crosses the hip joint (i.e., rectus femoris) — not to mention the other hip flexors also being stretched. Personally, some days I don’t feel a stretch in reclined hero pose until I employ a PPT.

 

Concluding Part 1

As I said at the beginning, this cue has stumped me since I began my yoga practice and we are far from ironing it all out. In today’s post we have seen how there is a definite place for the “tail-tuck” on the mat — it maximizes RA contraction and contributes to maintaining a hollow body position which is useful for many poses that are reliant on anterior chain activation. Moreover, the PPT is related to hip extension and can therefore also be a helpful movement cue in poses where we want to capitalize on that ability. What we haven’t yet explored is the relationship between the tailbone tuck and lumbar stability. Stay tuned for Part 2 of this series where we will explore this very topic!

 

References

  1. Drysdale CL, Earl JE, Hertel J. Surface Electromyographic Activity of the Abdominal Muscles During Pelvic-Tilt and Abdominal-Hollowing Exercises. J Athl Train. 2004;39(1):32-36. http://www.ncbi.nlm.nih.gov/pubmed/15085209. Accessed August 8, 2017.
  2. Neumann DA. Kinesiology of the Hip: A Focus on Muscular Actions. J Orthop Sport Phys Ther. 2010;40(2):82-94. doi:10.2519/jospt.2010.3025.

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