Fascia guide
Your psoas is a long muscle deep in your belly that links your lower spine to your thigh bone and helps lift your leg. Online it's blamed for back pain, a tilted pelvis, constipation and stored trauma, and tools are sold to release it.
The research is more ordinary. A short psoas hasn't been shown to cause back pain or pelvic tilt, digging into your belly carries real risks, and no study shows the muscle stores emotions.
What does help hips that feel tight is a well-placed stretch and some strength work. This guide shows both step by step, with a routine to follow.
The psoas runs from your lower spine to your thigh bone, deep at the back of your belly, and helps lift your leg. No study shows it stores trauma or emotions, and the therapies built on releasing stored trauma have weak evidence.
In 600 adults, a short psoas wasn't linked with back pain, but weaker hip flexors were. Hip extension didn't predict pelvic tilt, and back pain didn't predict hip flexor range once body weight was counted.
A half-kneeling stretch with the pelvis tucked under cut the hip flexors' resistance to stretch in a trial, and 6 weeks of band training made them 17% stronger. Strength work through the full range improves flexibility as much as stretching.
In two small trials of therapists pressing on the psoas through the belly, one found no extra pain relief and the other a short-term benefit against a fake release. Deep pressure in the belly has caused harm in case reports, so don't dig in with a tool.
Pain when you lift your knee, sprint or kick usually comes from a strained or irritated tendon or muscle, which our hip flexor pain guide covers. Psoas pain can occasionally come from an infection.
Source 15
The psoas major is a long, spindle-shaped muscle on each side of the lower spine. Its deep part starts on the first four lumbar vertebrae and its surface part on the lowest thoracic vertebrae and the discs. It joins the iliacus to form the iliopsoas, whose tendon passes under the groin ligament to the inner thigh bone, and the nerves of the lumbar plexus run between its layers.
It lies deep at the back of the abdomen, behind the lining that holds the gut and beside the lower end of the kidney. At its top, the lower edge of the diaphragm arches over it, and the fascia covering the psoas runs on upward. Anaesthetists who reach the nerves inside it from the back go 6 to 10 cm under the skin.
It works with the iliacus to lift the thigh, most of all in hard hip lifts, and it's active when you sit up straight and when the spine is held steady against a sideways load. Sit-ups use 15% to 35% of its maximum effort, curl-ups less than 10%. It has very little leverage on the curve of your lower back: one modelling study concluded it can't control that curve.
Fascia contains cells that can contract slowly: in laboratory tests on rat tissue, they contracted in response to chemical signals like those the body makes. That makes a link between long-term stress and stiffer tissue plausible but unproven, and it's a long way from storing memories.
Source 21
In a trial, the therapist had the patient lie with hips and knees bent and placed her fingertips midway between the navel and the bony point at the front of the hip. She confirmed the muscle by asking for a small leg lift, sank the finger pads backwards until she met firm tissue, and waited for it to soften: 3 to 5 minutes per technique. Tools sold for home use press the same way, and no trial has tested them.
Source 11
In 600 adults, half with low back pain, back pain went with poor endurance in the back muscles and with weaker hip flexors, inner thigh muscles and abdominals. The length of the iliopsoas, the size of the lumbar curve and the pelvic tilt weren't linked. These are associations, which can't show cause.
Source 5
In 25 healthy adults, hip extension range didn't correlate with pelvic tilt or the lumbar curve. In 23 men, one stretch session raised hip extension by 2.6 degrees and reduced tilt by 1.2 degrees without changing the curve, and the two changes didn't track each other.
Inactive people who sat for more than 7 hours a day had about 6 degrees less hip extension than active people who sat less. In 118 people not seeking care, those with back pain had a little less hip extension, but once body weight was counted, only body weight predicted it.
The modified Thomas test, lying back off the end of a table with one knee hugged in, misjudges hip extension unless the pelvis is held still. In one study it picked up only about a third of people with limited extension.
Source 24
Some studies find a smaller or fattier psoas in people with back pain, one found no link with pain or disability in 120 people, and one found a stiffer psoas in elite athletes with back pain. None shows that a short or tight psoas causes pain.
In 33 people with limited hip extension, 6 weeks of home stretching raised it, whether the stretching was active or passive. In a crossover trial of 26 active adults, adding a pelvic tuck to the half-kneeling stretch (2 holds of 30 seconds) cut the hip flexors' resistance to stretch by about a quarter, while the usual version changed it by almost nothing.
Across 11 trials and 452 people, strength training improved range of movement as much as stretching. In 33 healthy adults, about 10 minutes of elastic-band hip flexor training three times a week raised strength by 17% in 6 weeks.
In 40 professional footballers with long-term back pain and stiff hips, 8 weeks of supervised dynamic hip flexor stretching, 5 times a week, eased pain more than usual training, and part of the gain faded within 4 weeks of stopping. A trial of 100 people comparing two stretching methods had no group without stretching, so it can't show that stretching helped.
In 40 people with long-term low back pain, adding 4 sessions of psoas release to 8 physiotherapy sessions didn't ease pain more than physiotherapy alone. Disability scores ended slightly lower with release, but that result relied on adjusting for groups that weren't equal at the start, so it's uncertain. Follow-up was 4 weeks, and the patients and therapist knew who had which treatment.
Source 11
In 42 people with long-term low back pain, release of the diaphragm and psoas added to physiotherapy eased pain at rest by about 2 points out of 10 more than a fake release, and improved bending. Results were measured only at the end of treatment, and both muscles were treated together.
Source 12
For groin pain from the iliopsoas, exercise-based care succeeded in 77% to 100% of people in the studies reviewed. Surgical release of the tendon in hips without a replacement gave no clear benefit and went with muscle wasting and weaker hip flexion.
Source 33
2 holds of 30 seconds each side, with 30 seconds' rest between them: the trial's dose. Keep it a mild stretch.
Source 8
Standing band hip flexion, three times a week for 6 weeks: start with a band you could lift about 15 times and move to a stronger one until about 8 is hard, as in the trial. The trial trained one leg for about 10 minutes; doing both legs for 3 sets each is our editorial starting point.
Source 9
Our editorial starting point: straight-leg raises (2 sets of 8 to 10), dead bugs (2 sets of 6 to 8 each side), glute bridges (2 sets of 10 to 12) and reverse lunges (2 sets of 8 each side), as in the build stage of our hip flexor pain guide.
The stretching and band trials both ran for 6 weeks. Judge progress by how your hips move, not by a posture photo.
Long sitting with little activity goes with less hip extension. Standing up and marching on the spot for a minute or two each hour is our suggestion.
Source 23
Rolling the front of your thigh reaches the rectus femoris, a hip flexor, and changes how it feels for a while; the move page gives about 90 seconds per muscle. Leave your belly alone.
The steps come from the move's own page, and the dose of 2 holds of 30 seconds from the trial (González-de-la-Flor 2024). Pad the kneeling knee, and if kneeling hurts, use the standing hip flexor stretch instead.
Loading the 3D figure…
The movement on the figure: Half-kneeling hip flexor stretch
Strength first, 2 to 3 days a week (our editorial starting point).
3D demoStanding band hip flexionBeginner · A band + An anchor point
3D demoStanding marchBeginner · No equipment
3D demoStraight-leg raiseBeginner · No equipment
3D demoDead bugBeginner · No equipment
3D demoDead bug heel tapsBeginner · No equipment
3D demoGlute bridgeBeginner · No equipment
3D demoReverse lungeIntermediate · No equipment
3D demoSplit squatIntermediate · No equipment
3D demoStep-up with knee raiseIntermediate · A stepA mild stretch after strength work. The couch stretch is the strongest: skip it with knee problems or a suspected strain.
3D demoHalf-kneeling hip flexor stretchBeginner · No equipment
3D demoKneeling lunge hip flexor stretchBeginner · No equipment
3D demoStanding hip flexor stretch (split stance)Beginner · No equipment
3D demoLow lunge (Anjaneyasana)Beginner · No equipment
3D demoRunner's stretch (lunge and hip lift)Beginner · No equipment
3D demoCouch stretchIntermediate · A wallFor a looser feeling without pressing on your belly: roll the front of your thighs, breathe slowly, or slide your heels.
Start with the tight hip flexors routine, three times a week for 6 weeks.
Hips that feel tight: a tucked hip flexor stretch, then band knee drives, leg raises, dead bugs, bridges and lunges. Strength through range loosens hips too.
15 minBeginner8 movesA band, An anchor pointA 20-minute routine for anterior pelvic tilt: hip-flexor stretches, pelvic tilts, glute bridges, dead bugs, bird dogs and planks, for hip range and strength.
20 minBeginner10 movesA wallA 15-minute hip opener: 90/90 switches, windshield wipers, CARs, Cossack squats, frog and pigeon.
15 minIntermediate8 movesA wallA hip-opening yoga sequence: low lunge, lizard, goddess, pigeon, bound angle and happy baby.
20 minBeginner7 movesNo equipmentSeven stretches for after a run: calves, soleus, quads, hip flexors, hamstrings and glutes.
10 minBeginner7 movesA wallA 3-minute standing break to repeat every 30 to 60 minutes at your desk: sit-to-stands, calf raises, marching, an upper-back turn and chin tucks.
3 minBeginner5 movesA bench or box, A wallHealthLink BC, a Canadian health service, says to avoid massage of the belly in pregnancy, because firm massage of the pregnant belly could cause serious pregnancy problems.
Source 34
Don't press deep into your belly if you:
A woman's stent in the tube that drains the kidney moved out of place during deep Rolfing massage. In a man on blood thinners, a 14 by 17 cm bleed in the abdominal wall, which blocked the drainage of a kidney, followed repeated massage-gun use on his belly. A spontaneous bleed into the psoas itself was found in an 80-year-old man taking apixaban, a blood thinner, who did resistance training.
The psoas sits behind the lining of the gut and beside the kidney, with the nerves of the lumbar plexus running through it, and the artery to the kidney lies near its upper end. Nobody can feel exactly what's under a fingertip pressed that deep: even the release trial confirmed the muscle by asking the patient to tense it.
Stop, choose a position you can leave easily, and talk to someone trained. Our guide to exercise and post-traumatic stress disorder (PTSD) covers trauma-sensitive ways to move.
No study has tested it. Studies of Trauma Releasing Exercises (TRE) weren't consistently rigorous, somatic experiencing has only preliminary evidence of mixed quality, and a US guideline for veterans found too little evidence to recommend for or against somatic experiencing, yoga or relaxation training for PTSD. Strong feelings can come up when you stretch or lie still; that's a reason for trauma-sensitive teaching, not proof of stored trauma.
Its measured jobs are lifting the thigh and steadying the spine. Its link with the diaphragm is a shared attachment where the two meet, and no study shows that they tighten together with fear.
Psoas length wasn't linked with back pain, hip extension didn't predict pelvic tilt, and the psoas has little leverage on the curve of the lower back. The nerves of the lumbar plexus run through it, but no study shows that psoas tightness causes sciatica.
Stretching raised hip extension in trials, and strength work raised range as much as stretching. Deep release has two small trials, one of which found no extra pain relief.
We found no study showing it. Abdominal massage does help constipation, which may be where the idea comes from.
Source 42
Long sitting goes with about 6 degrees less hip extension, but that hasn't been shown to cause pain. Moving more and strengthening help range as much as stretching does.
With the iliacus, it lifts your thigh, and it helps hold your lower back upright when you sit tall. It runs from the sides of your lower spine, deep at the back of your belly, to the top of your thigh bone.
Usually a stiff or pulling feeling at the front of the hip, especially after long sitting. Inactive people who sit a lot do have a little less hip extension, about 6 degrees in one study. Pain when you lift your knee, sprint or kick is a different problem, which our hip flexor pain guide covers.
You don't need to dig for it. A half-kneeling stretch with the pelvis tucked under reduced the hip flexors' resistance to stretch in a trial, and band training made them 17% stronger in 6 weeks. Deep release by a therapist has only two small trials.
No trial has tested them. Pressing hard into the belly reaches the area around the kidney and the nerves that run through the psoas, and case reports describe harm from deep pressure. Don't use one if you're pregnant, take blood thinners, or have a hernia, an aneurysm or unexplained tummy pain.
Not on the evidence. In 600 adults, psoas length wasn't linked with back pain but weaker hip flexors were, and in another study back pain didn't predict hip flexor range once body weight was counted. In one small trial, footballers with back pain and stiff hips improved with 8 weeks of hip flexor stretching.
Hip extension range didn't predict pelvic tilt in healthy adults, and a stretch session changed tilt by about 1 degree without changing the curve of the lower back. The psoas also has little leverage on that curve. Our anterior pelvic tilt guide has the detail.
No study shows that. Therapies built on releasing stored trauma have weak evidence, and a US guideline found too little evidence to recommend them for post-traumatic stress disorder. Feelings can surface when you stretch or relax, and that deserves care, not a belief that your hips hold memories.
It's a nickname from some yoga and bodywork writing. What the psoas has been measured doing is lifting the leg and steadying the spine, and its link to the diaphragm is a shared attachment where the two meet, not a hidden emotional role.
One stretch session raised hip extension by about 2.6 degrees straight afterwards in a small study. Lasting gains came after about 6 weeks of regular stretching or strength training.
Walking works the hip flexors and stretches the front of the hip with every step, though no trial has tested it for tightness. Long sitting and inactivity go with less hip extension, so moving more is a sensible start.
Don't have deep pressure on your bump: firm massage of the pregnant belly could cause serious problems. Gentle hip flexor stretches can usually continue, but after the first trimester keep time lying flat on your back short. Our pregnancy guide has more.
We found no study showing that. Abdominal massage does help constipation, which is a different thing from releasing the psoas.
Movement education, not medical advice. Stop for sharp or increasing pain, numbness or tingling, and get individual advice if you are pregnant, after an injury or surgery, or managing a health condition. Health disclaimer.
