Piriformis syndrome: the deep buttock pain sitting on the sciatic nerve
Last updated September 3, 2026.
Piriformis syndrome is a deep buttock muscle (the piriformis) irritating the sciatic nerve that runs under or through it: causing a deep buttock ache, worse with sitting, often shooting down the back of the leg. It mimics the slipped disc (the sciatica feels similar), but the spine is innocent (the trouble is in the buttock), and it responds to the stretching, strengthening, and sitting-habit changes, with injections for the stubborn.
What does it feel like?
The pattern: a deep, aching pain in one buttock (the sitting-on-a-wallet spot), worse with sitting (the car journey, the desk day), worse climbing stairs, and often radiating down the back of the thigh (the sciatica imitation, sometimes past the knee), with tenderness deep in the buttock when pressed. Unlike the disc version: the back itself is usually fine (no back pain), and the sitting provocation is the hallmark. It builds from the running hills, the long driving, the new exercise program, or no obvious cause.
Why does it happen?
The piriformis (the deep rotator muscle of the hip) lies directly over (and in some people, around) the sciatic nerve, and when it tightens, spasms, or overworks (the running and the cycling, the prolonged sitting, the weak glutes making it overwork, the wallet in the back pocket), it squeezes or irritates the nerve beneath. The genuine slipped disc remains the commoner cause of sciatica (and the first thing the clinician excludes), which is why the diagnosis is a pattern judgment: buttock-centered, sitting-provoked, back-spared.
What actually helps?
- The piriformis stretching: the figure-four stretch (ankle on the opposite knee, drawn gently in), held through the day: the core self-treatment.
- The glute strengthening: the weak glutes are why the piriformis overworks: the bridges, the clams, the side-lying work: the physio-built program.
- The sitting changes: the wallet out of the back pocket, the sitting broken up hourly, the cushion, and the crossed-leg habit dropped.
- The manual therapy and the gliding: the physio's soft-tissue release and the nerve-gliding exercises.
- The injection for the stubborn: the image-guided steroid (or botulinum) into the muscle: the diagnostic-and-therapeutic step, with surgery the rare last resort.
When is it an emergency?
The leg-pain red flags, as ever: the bladder or bowel control changing or the saddle numbness (cauda equina: same-day emergency), the leg weakness progressing (the foot dropping), and the pain with fever, weight loss, or a cancer history. The ordinary buttock-ache-and-shoot pattern is physio medicine, and it genuinely responds. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
How is this different from a slipped disc?
The neighborhood is the same (both irritate the sciatic nerve and both shoot down the leg), but the address differs: the disc version pinches the nerve at the spine (the back itself usually hurts or stiffens, the pain worsens with bending and coughing, the nerve-stretch tests at the spine light it up, and the numbness and weakness can follow a root's map), while the piriformis version squeezes the nerve in the buttock (the back is clear, sitting is the great provoker, the deep buttock point is tender to press, and the back's tests are negative). The examination separates them in most cases (the physio's or GP's specific maneuvers), and the scanning question follows when they do not. The practical comfort: both respond to conservative treatment in the main, and your back-is-fine detail is the genuinely useful clue.
Why does sitting make it worse when sitting is rest?
Because for this condition sitting is load, not rest: the seated position presses the buttock's weight directly onto the piriformis-and-nerve sandwich (the car seat and the office chair are compression devices for this anatomy), the hip-held-bent position keeps the muscle on passive tension, and the stillness starves it of the movement that pumps it. Hence the signature: the long drive and the desk day are the flares, and the walking break is the relief. The management follows the mechanism: the sitting broken up hourly (the two-minute stand-and-walk is the dose), the cushion or the wedge, the wallet out of the back pocket (the classic literal pain-in-the-buttock), and the crossed-legs habit retired. Sitting is your sport's training load: program it.
What is the figure-four stretch, and how do I do it?
The core piriformis stretch, worth learning precisely: lying on your back, cross the sore side's ankle onto the opposite knee (the figure four), then draw the uncrossed leg toward your chest (hands behind that thigh), until a deep stretch is felt in the crossed side's buttock: held 30 seconds, repeated through the day, gently (the stretch should pull, never stab: the nerve underneath dislikes aggression). The seated version exists for the office. The progression pairs the stretch with the strengthening (the stretch relieves the tightness; the glute work fixes why the muscle tightened), and the stretching-then-sitting-all-day pattern is why stretching alone fails: the relief is real but temporary without the strength holding the gains.
Why is the strengthening the real fix?
Because the piriformis is usually the victim, not the villain: it is a hip stabilizer that tightens and spasms when the glutes (the hip's main engines) underperform (the piriformis drafted into the glutes' job, overworked into spasm, squeezing the nerve it merely sits beside), which is why stretching alone gives hours of relief and weeks of recurrence: the tightness is the symptom of the weakness. The strengthening program (the bridges, the clamshells, the side-lying leg work, the single-leg progressions the physio builds) restores the glutes to their post, the piriformis stands down, and the nerve stops being sat on. The running you started this year is also the program's payoff: the strong glutes are the runner's genuine injury insurance, so the rehab and the running ambition are the same work.
What if the exercises do not fix it?
The ladder beyond the program, in order: the physiotherapy intensified (the manual soft-tissue release of the muscle, the nerve-gliding techniques, and the program audited for what is missing), the image-guided injection (the steroid, or the botulinum into the piriformis: genuinely helpful for the stubborn, and useful diagnostically: relief confirms the address), the re-examination of the diagnosis (the disc, the sacroiliac joint, and the hip get reconsidered: the MRI question), and the rare surgical release for the genuine, confirmed, failed-everything cases. The timeline honesty: some cases run months despite good work, and the injection is the ordinary next step rather than an escalation to fear. The ordinary majority, though, responds to the stretch-strengthen-sitting program over the weeks, and the program is worth the genuine three-month trial.
Can I keep running while it heals?
The modified-continuation answer: running genuinely flat and gentle, at the volume that produces no pain during or after, is often permissible through the rehab (and the fitness is worth keeping), while the specific aggravators get benched: the hills (the piriformis works hardest climbing), the speed work, the long runs, and the cambered road. The cycling and the swimming cover the cardio in the genuine-flare weeks. The test for any session: the buttock should feel no worse during and no worse the next morning (the next-morning rule is the honest meter), and the return to the hills and the speed follows the strength milestones, not the calendar. The runner who fixes the glutes during the rehab returns faster and stays back: the piriformis is the invoice for the running form's weak link, and the rehab pays it properly.