Pelvis and lower back
SI joint stretches, and why stability usually beats stretching
The sacroiliac joint barely moves by design. When it hurts, the thing that tends to help is not making it move more.
Clinically reviewed by Lee Albert, NMT · 8 August 2026
A joint built not to move
The sacroiliac joints sit either side of the sacrum, where the base of the spine meets the pelvis. Unlike a hip or a shoulder, they are held by some of the thickest ligaments in the body and move only a few degrees. Their job is to transfer load between your spine and your legs, not to provide range.
That is why the word stretches is slightly misleading on this page, and worth saying rather than quietly ignoring. What usually settles this area is not more movement through the joint but better support around it: the muscles at the side and back of the hip doing their share so the joint is not being asked to absorb what they should.
The pattern that gives it away
It is usually one-sided, felt as a deep ache low down and slightly off-centre, in the dimple area rather than in the middle of the lower back. It often objects to single-sided loading: standing on one leg, climbing stairs, rolling over in bed, getting out of a car.
That last group is the useful clue. A joint that complains when you load one side is telling you something about how the two sides share work, which is what the sequence below is aimed at rather than at the joint itself.
What this sequence does
It runs in two halves. The first few movements settle the area and reduce what the joint is carrying, which is what most people are looking for when they search this. The second half is hip strength: the side of the hip, the back of the hip, and trunk control while one leg works.
Everything here keeps the pelvis level and stays away from the end of range, because pushing into end range on a joint like this is usually what stirred it up. If a movement asks the two sides of your pelvis to do very different things, it is not on this page.
The sequence
- 1
Legs up on a chair · 5 minutes or longer
Takes the load off the pelvis entirely and asks nothing back. A reasonable place to start on a day when the area is loud.
- 2
Knees to chest, single leg · 30 to 60 seconds each side
One side at a time, which is how this problem usually behaves. It also tells you whether the two sides feel different, which is worth knowing.
- 3
Supine twist, pillow between the knees · 60 seconds each side
The pillow keeps the pelvis stacked rather than letting it twist, which is the whole point here. Rotation without asking the two halves of the pelvis to separate.
- 4
Figure 4 with a strap · 60 to 90 seconds each side
Reaches the deep buttock muscles that sit directly over the joint and are often gripping. The strap sets the depth so you are not pulling with your arms.
- 5
Clamshell · 30 to 60 seconds each side
Where the second half starts. Side-lying, no weight through the pelvis, aimed at the muscle on the side of the hip that steadies you when you stand on one leg.
- 6
Bridge, block between the knees · 8 to 10 slow lifts
The squeeze keeps the pelvis working as one piece while the back of the hips lift it. That combination is what makes this version the one to use here.
- 7
Standing hip abduction · 30 to 60 seconds each side
The same side-of-hip muscle, now standing and holding the pelvis level. This is the position the problem actually shows up in.
- 8
Bird dog, small range · 5 each side, slowly
Trunk control while one side works, kept small deliberately. The aim is the pelvis staying still, not how far the limb travels.
Around fifteen minutes. The first four settle the area, the last four are the ones that change it, and skipping the second half is why this often comes back. Keep the pelvis level throughout and stay well short of end of range. Anything that produces a sharp catch low down on one side comes out rather than gets worked through.
What the research says
It is worth being straight about the evidence here rather than dressing it up: there is no large, high-quality trial base for sacroiliac-specific stretching, and any page that implies otherwise is overstating what is known. What exists is general guidance for low back pain, which is the family this usually gets managed within.
NICE NG59 covers low back pain with or without sciatica and recommends tailored self-management advice including encouragement to continue with normal activities, plus an exercise programme chosen around the person's needs, preferences and capabilities, which may be biomechanical, aerobic, mind-body or a combination. It does not prescribe a direction of movement or a named stretch for any part of the region.
On how much exercise does in general, the 2021 Cochrane review of exercise therapy for chronic low back pain pooled 249 trials and found moderate-certainty evidence that exercise beats no treatment, usual care or placebo for pain, with smaller effects on function. Neither source is about the sacroiliac joint specifically and neither endorses Vinys. Taken together they support the shape of what is below: keep moving, work the hips, and do not chase range from a joint that does not have much.
Sources
- 1NICE NG59, low back pain and sciatica in over 16s (2016, last updated 29 July 2026)
Provide tailored self-management advice including encouragement to continue with normal activities, and consider a group exercise programme (biomechanical, aerobic, mind-body or a combination) chosen around the person's needs, preferences and capabilities.
- 2Hayden et al., exercise therapy for chronic low back pain (Cochrane Database of Systematic Reviews, 2021)
Across 249 trials, moderate-certainty evidence that exercise is more effective than no treatment, usual care or placebo for pain (about 15 points on a 100-point scale), with smaller effects on function and only small differences against other conservative treatments.
Common questions
What is the fastest way to relieve SI joint pain?
Legs up on a chair takes load off the area with no effort at all, and it is the most reliable short-term comfort on this page. It is not a fix. What changes things over weeks is the hip strength work in the second half.
Should I stretch or strengthen an SI joint?
Mostly strengthen. The joint moves only a few degrees by design and is held by very thick ligaments, so chasing range from it rarely helps and sometimes irritates it. What helps is the muscles around the hip taking their share of the load.
Why does it hurt on one side only?
That is the typical pattern, because the two joints load independently. One-sided activities like stairs, standing on one leg or getting out of a car are the classic provokers, which is also why single-leg strength work is the sensible answer.
Is my SI joint out of place?
Very unlikely. These joints are among the most heavily reinforced in the body and do not slip in and out. Language about things being out and needing to be put back is common and not supported by how the joint is built.
How often should I do these?
The settling movements can be used whenever the area is uncomfortable. The strength half is worth three or so sessions a week, since that is the part that accumulates rather than the part that soothes.
Could it be something else?
Possibly, which is why persistent one-sided pain low in the back deserves an assessment. Hip problems, the lower lumbar joints and the deep buttock muscles all refer to a similar area, and they are managed differently.
Seek urgent care for numbness around the groin or back passage, any change in bladder or bowel control, or weakness in a leg. See a clinician rather than starting a routine if the pain followed a fall, if you are pregnant or recently postpartum and the pain is severe, or if it comes with fever or unexplained weight loss. Stop anything that produces a sharp catch on one side.
Also called si joint stretches, sacroiliac joint stretches, si joint pain exercises, sacroiliac exercises, si joint stretches for pain relief, stretches for si joint pain. Movements are drawn from the clinically authored Vinys library. This page is general movement information, not medical advice, and it is not a diagnosis. How the method works.