Why This Matters Clinically

SIJ stability depends on two mechanisms. Form closure refers to the joint's passive stability from its interlocking bony surfaces and ligaments. Force closure refers to the dynamic stability generated by muscle activation across the joint — specifically the posterior oblique sling (gluteus maximus to contralateral latissimus through thoracolumbar fascia), anterior oblique sling (oblique abdominals and contralateral adductors), and longitudinal sling (erector spinae, biceps femoris, sacrotuberous ligament). SIJ instability and pain is most effectively addressed by rebuilding force closure capacity rather than bracing or protecting the joint from all loading.

Exercise Progression

Posterior oblique sling activation: Prone hip extension with contralateral arm reach — lying face down, extend one hip (activate glute max) while simultaneously reaching the opposite arm forward (activate latissimus). Hold 5 seconds, 10 repetitions each side. This specifically trains the posterior oblique sling — the most important force closure mechanism for the SIJ.

SIJ compression exercise: Side-lying, knees bent, resistance band around the knees. Squeeze both knees into the band (adduction) while simultaneously activating the glutes. This generates compressive force across the SIJ through the coordinated action of the adductors and pelvic floor. Hold 10 seconds, 10 repetitions.

Hip thrust with focus on pelvic position: Standard hip thrust with attention to maintaining a neutral pelvis at the top of the movement — not hyperextending the lumbar spine. The top position isometrically loads the gluteus maximus as a posterior oblique sling contributor.

Pallof press: Standing, cable anchored at hip height to the side. Hold cable at sternum with both hands, press it straight forward against the rotational pull of the cable. This anti-rotation exercise trains the anterior oblique sling and challenges the SIJ against lateral shear forces in a functional upright position.

The active straight leg raise (ASLR) as a treatment monitoring tool: The ASLR — raising one straight leg 20 cm off the floor in supine — loads the SIJ through the leg's weight acting as a cantilever force. A positive ASLR (heavy, difficult, or painful) indicates impaired force closure. Reassessing the ASLR after targeted force closure exercises provides immediate feedback on whether the exercises are appropriate: if the ASLR becomes easier after 3–4 sets of posterior oblique sling work, force closure capacity has acutely improved and the exercise selection is correct.

Programming Guidelines

Train 3× weekly with 48-hour recovery between sessions. Begin at the level where movement quality is excellent and symptoms are 0–2/10. Progress load, range, or complexity only when the current level is performed without compensation across three consecutive sessions. Allow 8–12 weeks for functional strength to meaningfully improve in a rehabilitation context.

References & Further Reading

  1. Vleeming A, et al. European guidelines for the diagnosis and treatment of pelvic girdle pain. Eur Spine J. 2008;17(6):794–819.
  2. Lee DG, Lee LJ. Integrated Approach to the assessment and treatment of the lumbopelvic-hip region. Advances in Physiotherapy. 2011;13(2).
  3. Richardson CA, et al. Therapeutic Exercise for Lumbopelvic Stabilization. Churchill Livingstone; 2004.