SI joint pain doesn't mean you stop running or training. Our fellowship-trained Doctors of PT diagnose the root cause — SI dysfunction, sacroiliitis, or postpartum instability — and build a plan to get you back to full activity.
Common Diagnoses
SI joint pain isn't just one thing. Click each section below to learn about the three most common causes we see in runners and athletes — and what to do about each one.
Sacroiliac (SI) joint dysfunction is pain arising from the SI joint — the joint connecting the sacrum (base of the spine) to the pelvis. It's one of the most common causes of low back and buttock pain in athletes, particularly runners and single-leg sport athletes.
SI joint dysfunction happens when the joint is overloaded, or becomes either too loose (moving too much) or too stiff (not moving enough) compared to the other side. Common contributing factors include:
We identify the root cause — weak glutes, poor hip mobility, or faulty mechanics — and build a progressive loading program to fix it. Manual therapy to restore SI joint mobility combined with targeted strengthening resolves most cases. Athletes can usually stay training with modifications.
Sacroiliitis is inflammation of the sacroiliac joint, often associated with inflammatory conditions like ankylosing spondylitis or reactive arthritis. Unlike mechanical SI joint dysfunction, sacroiliitis is inflammatory in nature and typically presents with bilateral pain and morning stiffness.
Sacroiliitis is caused by inflammatory processes rather than mechanical overload. Contributing factors include:
While sacroiliitis often requires medication from a doctor — anti-inflammatories or specialty drugs that calm the immune system — physical therapy plays a critical role in maintaining mobility and function. We use joint mobilization, anti-inflammatory exercise, and postural education to reduce pain. Co-management with a rheumatologist is often necessary for inflammatory cases.
Postpartum SI instability occurs when the ligaments supporting the SI joint become lax due to hormonal changes during pregnancy (primarily relaxin), leading to excessive motion and pain. It's extremely common in postpartum women and can persist months or years after delivery if not properly addressed.
Postpartum SI instability is caused by ligamentous laxity combined with weak stabilizers. Contributing factors include:
We use progressive core and hip strengthening to compensate for ligamentous laxity and restore pelvic stability. SI joint belts can provide temporary support during acute phases. Most postpartum SI instability resolves with proper rehab, though it requires patience as ligament healing takes time (6-12 months).
Evidence-Based Resources
SI joint pain doesn't mean you stop running. A Doctor of PT breaks down the root causes and gives you 3 evidence-backed exercises to keep training.
Pelvic pain after pregnancy is common but not normal. Here's how to rebuild core and hip stability to eliminate SI joint pain.
Book a free 15-minute phone call with a Doctor of PT. We'll figure out what's going on and build a plan to get you back to training.