What bending backwards asks of the back, and who gets painEmerging evidence
Arching the lower back closes up the back of the spine. The facet joints (the small paired joints at the back of each vertebra) take more of the load: in cadaver spines, about 16% of the squeezing force standing upright, against none sitting. The pars, a thin bridge of bone at the back of each vertebra, is loaded too, and the spaces the nerves pass through narrow, which is why an NHS leaflet says "standing straight can narrow the space for the spinal nerves" in stenosis.
Three groups get most of the pain: anyone with an ordinary back strain, which can be sore in any direction; young athletes who arch again and again, at risk of a stress fracture; and people from mid-life, in whom facet joint changes, slips and narrowing become more common. No study counts the causes of pain on arching, so the map on this page is built from what each condition is known to do.
Sources 1, 2, 3, 4, 5, 6, 7, 8
Ordinary back pain, and a sore directionStrong evidence
The NHS says a common cause of back pain "is an injury like a pulled muscle (strain)" and that it "usually improves within a few weeks". Across 33 groups (11,166 people), new back pain fell from 52 to 23 out of 100 within 6 weeks, and to 6 by a year; pain that had already lasted a while improved more slowly.
Many backs hurt one way and ease the other, which clinicians call a directional preference. In 312 people with back pain, 74% had a direction (bending forward, arching or to the side) that eased their pain, and across 5 studies (2,368 people) about 70% did. So "it only hurts when I bend backwards" is a pattern, not a diagnosis.
Sources 3, 9, 10, 11
Pain on arching doesn't prove it's the facet jointsStrong evidence
In 176 people with long-lasting back pain, 47% responded to a first numbing injection into the facet joints but only 15% to a confirming one, and no symptom picked them out. Reviews of 41 and 62 studies found no examination test that identifies facet joint pain. The best-known set of facet signs (Revel's criteria) actually included pain that was not worse arching back, and it didn't hold up when retested in 116 people.
At one US spine centre, the facet joints were judged the source in 31% of 170 people with long-lasting back pain, more often with age, but these were selected clinic patients. Facet "wear" is common on scans of people without pain: about 18% at 40, 50% at 60 and 83% at 80. From mid-life, an arching-sore back is often labelled facet joint pain, and it is managed like other back pain.
Sources 12, 13, 14, 15, 16, 17, 6
In a young athlete who arches a lot, pain that lasts can be a stress fractureStrong evidence
Spondylolysis is a stress fracture of the pars. At one children's hospital sports clinic, it was found in 47 of 100 adolescent athletes with back pain, against 5 of 100 adults with new back pain; at another, in 30% of 1,025 non-elite adolescent athletes with back pain. Pars defects are commonest in diving, cricket, baseball and softball, rugby and weightlifting, with 13.8% of 1,391 gymnasts across 11 studies, and the American Academy of Orthopaedic Surgeons (AAOS) names sports with "frequent overstretching (hyperextension)" of the lower back.
Our warning line says to get a teenager's back pain checked if it lasts more than a couple of weeks. That 2-week threshold comes from one clinic study: in a Japanese orthopaedic clinic, 136 under-19s whose back pain had lasted more than 2 weeks had a magnetic resonance imaging (MRI) scan, and 39.7% had spondylolysis, all of them active in sport. The NHS spondylolisthesis page uses 3 to 4 weeks for adults, and the AAOS says to see a doctor if a young child's back pain lasts "more than several days". In English professional fast bowlers, a peak week of more than 234 deliveries went with 11 times the odds of a lumbar stress fracture, and the England and Wales Cricket Board (ECB) says young bowlers in or just after a growth spurt are at greatest risk.
Sources 18, 19, 4, 5, 20, 21, 22, 23, 24
Spinal stenosis, slips and inflammatory back painStrong evidence
From about 60, buttock or leg ache, heaviness or tingling that comes on when you stand or walk and eases when you sit or lean forward points to spinal stenosis: NHS inform says the leg symptoms are "usually worse with walking or standing, and are relieved by sitting or leaning forward". Leaning back narrows the space for the nerves further. It is rare under 50.
A slipped vertebra (spondylolisthesis) brings back pain "often worse when standing or walking and relieved when sitting or bending forward", the NHS says. Slips from wear are commoner over 50 and in women, often with stenosis; slips from a childhood stress fracture "very rarely" get worse, the AAOS says. Back pain that started before 45, has lasted more than 3 months, is stiff in the morning and eases with movement can be inflammatory back pain; NICE asks GPs to refer people with 4 or more of 9 features to a rheumatologist.
Sources 25, 8, 2, 21, 7, 26
Yoga, dance, gymnastics and fast bowlingEmerging evidence
Back bends (cobra, upward dog, camel, wheel, walkovers, cambrés) arch the spine to the end of its range. The only data on yoga back bend injuries come from one clinic series: of 89 people seen at one US spine clinic for injuries they put down to yoga, the poses most often involved extreme bending or arching, and flares of facet joint arthritis (38%) and slips (17%) were among the problems. It had no count of how many people did yoga safely. Across 94 trials (8,430 people), yoga was as safe as usual care and other exercise.
Dancers report low back pain often (a median of 73% in a year across 50 studies), and competitive gymnasts 25% to 50%, more in rhythmic gymnastics. The ECB explains that fast bowling arches, bends and twists the lower back under heavy load. These are surveys and case series: they show what can go wrong, not how often back bends cause it.
Sources 27, 28, 29, 30, 24
What a scan or test shows, and when it mattersStrong evidence
For most back pain, NICE says "Do not routinely offer imaging in a non-specialist setting", and the Chartered Society of Physiotherapy (CSP) answers the idea that a scan will show what's wrong with "Sometimes it will, but most often it won't". Facet changes and slips are common in people without pain, and in 188 US adults, cracks in the pars on computed tomography (CT) scans (11.5%) weren't linked with back pain; 5.9% of 2,000 Japanese adults scanned for other reasons had them.
A young athlete with lasting pain is the exception. The one-legged arching ("stork") test is unreliable (it missed up to half of stress fractures and gave many false alarms), so the diagnosis needs a scan, and MRI is preferred because it avoids radiation and picks up early stress reactions; it matched CT and other scans closely in small studies. US radiology guidance cited by a family medicine review delays imaging in children in general unless there are nerve signs, night pain, spreading pain or pain beyond 4 weeks. For adults with leg pain, numbness or weakness, the NHS may arrange an MRI.
Sources 31, 32, 6, 33, 34, 35, 36, 37, 38, 39, 40, 21
How it usually goesEmerging evidence
Ordinary back pain improves most in the first 6 weeks, more slowly after that. Young athletes with a stress fracture mostly return to sport: a median of 74 days with early physiotherapy in the one trial, though fast bowlers may be out for up to 8 months, and in one follow-up about 45% had significant symptoms again within 3 to 4 years. Stenosis symptoms improve or stay the same in up to 60% of people with mild to moderate symptoms, a hospital trust says.
In 500 schoolchildren followed into adulthood, pars defects rose from 4.4% at 6 to 6% in adults, and slips rarely got worse after adolescence; 45 years on, people with the defects had a quality of life like everyone else's. No one can promise a date.
Sources 9, 41, 24, 42, 8, 43, 44
