This blog was adapted from its original post on https://drlaurenkeller.com by the author.
Whether you are sitting in a chair all day feeding your little one, lifting weights, or pregnant, the position of your spine matters. In fact, in all three instances we want the same thing: a neutral spine. To tuck the pelvis (butt wink) or extend the spine (stick your booty out) – that is the question. Actually, the answer is neither: we want a happy medium of both and here is why.
The Mechanics of the Butt Wink vs. Sticking your Booty Out
Tilting the pelvis too far forward (anterior pelvic tilt) or tucking it too far backward (posterior pelvic tilt) can exaggerate or minimize the natural curve of the spine and cause pain, discomfort, or instability through the following mechanics:
Tucking/Butt Winking:
Pelvic tucking is called a posterior pelvic tilt and is created when the pelvis rotates backwards (posteriorly). It is called many things, including: tucking, butt wink (at the bottom of a squat), bottoming out; this is the position typically achieved when someone rounds out their lower back. When this happens, the coccyx (tailbone) moves down and forward. At the same time the pubic symphysis, which is in the front of the pelvis, moves forward and up towards the navel.
By tucking, the lumbar spine actually moves into flexion and can pull the ribs down in a shearing motion that puts the abdomen almost into a crunch position by shortening the abdominal musculature. This movement also shortens the hamstrings while lengthening the quadriceps and back musculature. One common symptom of pelvic tucking is “constantly tight hamstrings” that feel tight despite continually being stretched.
One reason people will tuck the spine is to activate the glutes which can create a sensation of constant butt clenching. This movement actually causes chronic tightening of the gluteal muscles and external hip rotators as this movement can pull the femur head back and externally rotate it, causing widening of the pelvic floor and weakening of the pelvic floor muscles.
Lumbar Flexion/Sticking the Booty Out:
Lumbar extension, or an increased curvature of the low back, creates an anterior pelvic tilt and is created when the pelvis rotates forward (anteriorly). When this happens, the low back goes into hyperlordosis, and a person appears to literally dump out the front. In this instance, the hamstrings and abdominals are lengthened while the quadriceps and back musculature are shortened, causing the psoas and spinal erectors to be hyperactive. We frequently see this in pregnant women as they compensate for the changes their body is making in order to find a stabilizing position. In the gym, we see this movement during common exercises like the squat or deadlift. One common complaint people with anterior pelvic tilt have is that they “always need to stretch the psoas/hip flexors”.
This position can also elevate the ribs and create a concentric abdominal wall while creating an oblique position of the diaphragm and pelvic floor, causing pelvic floor instability and an inability to optimally use the diaphragm.
Forward Sway & Sway-Back
This move is a hybrid of the two previous moves as the person tucks the pelvis but sways their upper back backwards to make it appear like they have a lumbar lordosis or low back extension. In fact, the low back is in flexion and the thoracolumbar region (the mid-to-low back) is hyperextended. In this position, we commonly see the butt pointing downwards (the pubic symphysis is forward of the ASIS, the bony points on the top of the hips), the hips are hyperextended and the knees are fully extended.
Wait a Minute.
Did I just say that BOTH movements can cause diaphragm and pelvic floor dysfunction? Yep, that’s correct. While we all want a good looking booty, we don’t want our butt muscles to come from either movement: butt clenching or sticking the booty out; we don’t want either— we want a neutral spine.
.
What is a neutral spine?
Stay tuned for part 2 to dive a little deeper!
Lauren Keller, DC, DABCA
BIRTHFIT Chicago: Western Suburbs
Instagram: @birthfit_chicago_western_burbs
Facebook: @birthfitchicago
Resources:
- Cholewicki J, Panjabi MM, Khachatryan A. Stabilizing function of trunk flexor-extensor muscles around a neutral spine posture. Spine. 1997;22(19):2207–2212.
- Wallden, Matt. The neutral spine principle. Journal of Bodywork and Movement Therapies, Volume 13 , Issue 4 , 350 – 361
- Panjabi, Manohar. (1993). The Stabilizing System of the Spine. Part II. Neutral Zone and Instability Hypothesis. Journal of spinal disorders. 5. 390-6; discussion 397. 10.1097/00002517-199212000-00002.
- Jagarinec, Tomi. (2017). Core Training in Football: Improve Your Players’ Posture and Unlock Their Play Potential.
- Bendix, T & Biering-Sørensen, F. (1983). Posture of the trunk when sitting on forward inclined seals. Scandinavian journal of rehabilitation medicine. 15. 197-203.
- Richardson, C, Jull, G, Hodges, P, Hides, J. Therapeutic exercises for spinal segmental stabilization in low back pain. Churchill Livingstone, Toronto; 1999.
- Elia, DS, Bohannon, RW, Cameron, D, Albro, RC. Dynamic pelvic stabilization during hip flexion: a comparative study. J Orthop Sports Phys Ther. 1996;24:30–36.
- Robinson, R. The new back school prescription: stabilization training part 1. Occup Med. 1992;7:17–31.
- Dumas, GA, Reid, JG, Wolfe, LA, Griffin, MP, McGrath, MJ. Exercise posture and back pain during pregnancy: part 1. Exercise and posture. Clin Biomech. 1995;10:98–103.
- Effects of pelvic tilt angles and forced vital capacity in healthy individuals.
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