One day when I was practicing Upavistha Konasana (Wide-Angle Seated Forward Bend), I stretched to one side. I firmly anchored my pelvis, keeping my sitting bones on the floor, then I twisted toward my left leg and reached for my left foot with both hands. Suddenly I heard a loud and ominous “pop!” I came out of the pose immediately. Over the next few days, I noticed increasing discomfort around my right sacroiliac joint. The pain prevented me from practicing seated and standing twists, and made forward bends unpleasant as well.
A trip to an orthopedist didn’t provide any relief. The pain persisted, and I was left to figure out on my own what was going on in my back.
For the next week, I devoted my practice to only one type of pose per day. I practiced only seated twists one day; the next morning, I could hardly get out of bed. Clearly I was practicing twists in a way my body didn’t like.
Yoga instructors often tell students to “anchor the sitting bones” while doing seated twists. But I discovered the hard way that the pelvis and sacrum must be allowed to move together while doing this movement. Anchoring the pelvis and simultaneously twisting the vertebral column separates the sacroiliac joint and strains the ligaments around it. When I changed the mechanics of my twisting practice, my pain resolved itself and never returned.
More: Explore twist yoga poses
The structure of your sacroiliac joint
The ilium bones of the pelvis and the sacrum come together at the sacroiliac (SI) joint. This is a joint of stability, not mobility. While movement at the joint is allowed in order to facilitate walking, and moving from standing to sitting and back to standing, this movement is only about two to four millimeters. Honoring this stability is the key to maintaining a pain-free sacroiliac joint when you practice yoga asana.
Many broad, strong ligaments hold the sacrum and the pelvis together (see illustration, above). The integrity of these ligaments is very important for maintaining upright posture, as well as for walking, squatting, lifting, sitting, bending, and reaching.
How your body moves in twisting postures
The sacroiliac ligaments keep the pelvis together while allowing the little bit of slippage we need, especially while walking, and moving from sitting to standing and vice versa. When we move, we almost always move our sacrum and ilium bones in harmony.
Let’s apply the understanding of the sacrum as a stabilizing joint to the practice of twisting in yoga asana. Sit on your yoga mat in Bharadvajasana (Bharadvaja’s Twist) so that you are resting mostly on your left thigh and buttock with your knees bent and legs swung to the right.
Anchor your sitting bones and pelvis. Then place your right hand on the outside of your left thigh just above your knee. Exhale, ground your sitting bones, and try to twist without moving your pelvis. You won’t be able to turn very far. The twist will come from the lower thoracic spine, which can be unpleasant at best and painful at worst. This is because when you anchor your pelvis and twist your spine, you are rotating the spine in one direction and the pelvis in the other. You are stressing the sacroiliac ligaments, likely overstretching them in an attempt to twist more. This creates laxity in the joint and sets you up for chronic sacroiliac pain and sometimes swelling around the joint.
Now try the pose again. This time, imagine the anchor of the pose is not the pelvis or sitting bones, but the very top of your left thigh, where it meets your abdomen. Anchoring from there, exhale and twist by moving the pelvis over your hip joints. Keep pressing down with your right thigh even though it will lift a little. Your right buttock may also lift slightly, but that is actually part of the pose as long as you are moving the hip sockets around and over the femoral (thigh bone) heads and creating the movement from the hip joints. Now, your pelvis is moving with the spinal column, not in the opposite direction.
Rethinking how you twist
In starting your twisting poses from this new perspective, you shift your idea of where you anchor such poses. Instead of rooting the sitting bones and pelvis, you’re anchoring your legs. You create many other poses through the hip joints, especially forward bends and standing poses. In these poses, you’re stabilizing the pose with your legs. Do the same thing in the twists.
The key to healthy movement in twists is simple: Move from your pelvis. Twisting this way protects the sacroiliac joint because it keeps the pelvis and sacrum moving together.
Structural differences & considerations
Differences in pelvic structure, as well as hormonal differences, can influence the stability of the sacroiliac joints. People born in male bodies tend to have a pelvis that is smaller, longer, more curved, and narrower in shape. For people born in female bodies, the pelvis is wider at the top with a shorter, wider, flatter, and more vertically oriented sacrum. There may be a proportionally wider distance between their hip sockets, and the sacroiliac joint itself is shallower. Less depth in a joint creates less stability.
When you step forward with the right leg to walk, the right pelvis torques (twists or turns) forward and the left pelvis torques back. This is true in all human bodies. But when the hip sockets are farther apart, there is more torque (and therefore more stress) applied across the sacroiliac joints than there would be for someone of the same height and bone structure who has a narrower space between hip sockets.
The hormonal changes of menstruation, pregnancy, lactation, and childbirth can also affect the function of the sacroiliac ligaments. These hormones can cause ligaments throughout the body to be more lax generally, in part to allow the pubic symphysis to spread during childbirth. When this opening happens, it also stresses the ligaments holding the sacroiliac joints on the back wall of the pelvis.