The SI joint: anatomy, and thoughts on training people with SI joint issues


The sacroiliac (SI) joint is one of those areas that gives people trouble. Having “SI joint issues” is akin to having “shoulder issues” or “hip issues.” Because I occasionally work with dancers and yogis (i.e., people that have a lot of mobility), it’s not uncommon for SI joint pain to come up. I am going to discuss working with people that have non-specific SI joint pain and have already been through physical therapy; if you experience SI joint discomfort or are working with someone with SI joint discomfort that is chronic, you need to see a physical therapist/osteopath or refer out. (I had someone in the last four months who had been managing her SI joint pain with physical therapy, me for more restorative movement, and vigorous strength training. She took an inexplicable turn, and I noticed she was unable to hold any sort of stability in her pelvis while standing. I referred her out to a PT that does mobilizations and Pilates based rehabilitation. This was what she needed and she is doing really well- SI joint pain is gone). This area is tricky, and the stability is heavily reliant upon the ligamentous structures of the joint. If the ligaments become overstretched, stability becomes compromised. Ligaments become overstretched by spending time in passive “lengthening” positions, something dance and some forms of yoga emphasize. Post rehabilitation of SI joint pain in a flexible population needs to focus on stability first, mobility second. But lets look at the anatomy to understand why.

The sacrum is a flat bone that comes after the fifth lumbar vertebrae. It is five vertebrae fused together. Between S1 and S3, the sacrum joins forces with the innominate bones of the pelvis to form the SI joint (Disfonksiyonu, 2010). More accurately, the interface between the sacrum and ilium comprises 1/3 of the junction. The other 2/3 consists of ligamentous structures (Cohen, 2005). There are several muscles that support the SI joint and allow force to be transmitted to the pelvis. The gluteus maximus, piriformis, and biceps femoris are functionally connected to the SI joint ligaments. This means their actions affect joint mobility (Cohen, 2005). If you are drowning in the complexities of the anatomy right now, stop and consider this. Your hamstrings and your butt muscles provide support posteriorly at the SI joint. If you work with any population that has stretched their hamstrings into bits and lack glute strength, creating stability in this area needs to include strengthening the hip musculature and mobility in this area should be done in strength based manner to support the joint. Further, the thoracolumbar fascia (TLF) assists in maintaining lumbar spine and SI joint stability* (Willard,, 2012). The TLF divides the front and back of the torso, separating the paraspinal muscles from the posterior abdominal wall, namely, the transverse abdominis. This indicates that to create a sense of stability in the SI joint requires access the deep abdominals. An easy way to see if the deep abdominals are working to stabilize the pelvis is to have someone lie down with their knees bent. Ask the individual to lift a foot off the floor. If the pelvis tips to one side or the superficial muscles of the abdominals puff up, chances are high the person has difficulty accessing the deeper abs. In addition, think about what this means where the pelvis meets the sacrum. In a low level exercise such as lifting the leg, the pelvis shouldn’t need to move transversely; you can begin to imagine what’s happening in higher level exercises. This isn’t to say the pelvis shouldn’t ever move. It absolutely should, and in fact, if a pelvis is locked down, this can potentially lead to a different host of inefficiencies. 

Something else to consider regarding the SI joint is there can be discrepancies in size, shape, and surface contour in the same individual. This means the two sides might behave differently, which might affect programming. For instance, if you notice someone’s right hip juts out to the right every time she performs a basic step up, but the left doesn't you might approach your cueing and your warm-ups on the right side differently than you do the left. In clients that have a lot of mobility and complain of SI joint discomfort, I frequently see side to side movement in the pelvis. Again, consider how inefficient doing this repetitiously is for force absorption. It’s not necessarily a bad thing, nor does it guarantee pain, but it’s not the most efficient way to walk up stairs.

So what does all of this indicate? Here are some things I have found to be effective during warm-ups in clients that are post-rehab or struggle with the “occasional” SI joint flare up.

  • Breathe. Probably no surprise here, if you follow my work at all. I like using long exhales and exhale retentions to get into the deep core muscles. I find Joanne Elphinstin’s Greyhound 2.0** exercise is really useful at quieting movement in the pelvis during supine movements. Depending on how I cue, this can translate really well to standing movements as well.
  • Develop foot awareness. The feet are your first point of contact with the ground. The SI joint transmits forces across the pelvis to the torso. Foot awareness matters.
  • Work the hamstrings in isolation, using isometric contractions. If you would have told my younger self I would be into isolated hamstring work, I would have scoffed. My wiser (i.e. older) self has seen this work remarkably well. I use prone, bent knee and supine, extended leg pressing into the floor*** to begin teaching what the hamstrings feel like. This moves pretty quickly into standing RDL deadlifts, once body awareness and motor control have improved.
  • Bent knee side planks, ala DNS. I use the bottom knee pressing into the ground to get awareness of the glute muscles, and cue lifting the ribs away from the floor to ensure even waists.
  • Once stability is gained, transverse plane movement. Or rotational movement, or rotating the ribs. Whatever you want to call it. Teaching people to rotate rather than only having the option of moving side to side is powerful.

In the case of SI joint pain and someone that’s bendy, finding strength and a sense of stability can make a dramatic difference in how the person feels. As always, not everything works for every person, but I share with you the things that have worked with my clients. And remember: these individuals probably don’t need to stretch their hamstrings.

Yours in health and wellness,

*This article on the TLF by Williard and CO is epic. If you are interested in this area at all, you should read it.
**Joanne Elphinston’s book, Stability, Sport, and Performance Movement is worth a read if you are looking for ways to bridge the gap between rehab and performance.
***If you want to see a Youtube of some of these exercises, click here:

Disfonksiyonu, S.E., (2010). Sacroiliac joint dysfunction. Turkish Neurosurgery, 20(3), 398-401.
Cohen, S.P., (2005). Sacroiliac joint pain: a comprehensive review of anatomy, diagnosis, and treatment. Anesthesia & Analgesia, 101(5), 1440-1453.
Williard, F.H., Vleeming, A., Schuenke, M.D., Danneels, L., & Schleip, R., (2012). The thoracolumbar fascia: anatomy, function, and clinical considerations. Journal of Anatomy, 221, 507-536.