What a Russian twist asks of the back, and what no study has measuredEmerging evidence
In the usual version you sit with your knees bent, lean back to about halfway with a long spine, and turn your ribs and shoulders from side to side; harder versions lift the feet and add a weight. The National Academy of Sports Medicine (NASM) starts beginners with body weight and lists rounding the spine and jerky turns among the common mistakes. The tummy muscles hold the lean back, and with your feet up the hip flexors hold your legs.
The lean back itself rounds the lower back. In 20 adults, the lower spine was 28 degrees more bent in a V-sit than in a plank, with similar tummy muscle activity in another 30. The turn is started by the outer oblique on one side and the inner oblique and latissimus dorsi on the other, and in 50 young adults muscle activity rose as turns got faster even though the turning force fell; the authors advise keeping load and speed low.
No study has measured the Russian twist's muscle activity, spine load or safety, and none counts back pain from it. A review of 67 studies of core muscle activity in fitness exercises has no Russian twist data. So this page is built from studies of twisting, bending and the V-sit, trials of exercise for back pain in general and NHS pages.
Sources 1, 2, 3, 4
Where it hurts, and who gets itEmerging evidence
No study gives the share of each cause in Russian twists. An ache across the lower back as you lean back and turn is usually ordinary low back pain, the commonest kind: the NHS says a common cause of back pain is a pulled muscle (strain), and that back pain is very rarely a sign of something serious such as a broken bone, cancer or an infection.
The people it usually bothers, in our reading: people who jump to the feet-up, weighted or fast version, or to high-rep challenges; people whose back already dislikes bending forward; people who slump into the lean back; people training on a hard floor; and people back after a baby or a hernia repair, or with thin bones.
Source 5
Bending and twisting together: what the lab studies show, and don'tMixed evidence
The lower back hardly twists. In 10 volunteers turning their trunks 45 degrees in a scanner, lying down, each lower back joint turned only 1.2 to 1.7 degrees. In cadaver spines, the small facet joints resisted most of a twist, and the authors concluded that twisting seems unimportant in disc wear and prolapse. But a partly bent joint behaves differently: some lumbar joints turned further when partly bent, and the authors wrote that bending with twisting raises the disc's vulnerability.
The animal studies are mixed. In pig spines, twisting combined with repeated bending split the layers of the disc wall in 67.5% of specimens, while twisting alone couldn't start a herniation, and repeated bending under load alone, over up to 86,400 cycles, herniated young pig discs. In 25 sheep discs held bent, adding a small twist made one kind of tear easier and another harder; in 30 sheep discs loaded 1,000 times, bending and side bending mattered more than twisting, and no herniation happened; in 12 cow tail discs, fewer cycles of even bending and twisting kept the disc healthy, while more cycles and one-sided loading split its outer wall.
These are dead animal tissues loaded far beyond any workout, and living tissue adapts. In 861 workers followed for 3 years, twisting at work carried a small, uncertain rise in back pain risk that could have been chance. Our reading: fast, loaded, repeated twisting with a rounded back is the version to be careful with, especially when your back is already sore, not proof that a Russian twist harms a healthy back.
Sources 6, 7, 8, 9, 10, 11, 12, 13, 14
Your feet and the hip flexorsEmerging evidence
In 6 men, bent and supported legs raised hip flexor activity in sit-ups without adding tummy muscle work, and in 8 adults every form of sit-up worked the psoas, a hip flexor joined to the lower spine, at 15% to 35% of its maximum. A modelling study found that at full effort the psoas squeezes the lower spine hard.
No study has measured a Russian twist with the feet up and down. That lifting your feet asks more of the hip flexors and adds to the load on a sore lower back is our reading of these sit-up studies and the model. It fits why people search for Russian twists hurting their hips and thighs, and why the feet-down version is the place to start.
Sources 15, 16, 17
The side of the trunk, the sacroiliac joint and nervesEmerging evidence
A sudden sharp pain at the side of the trunk during a hard twist is more likely a strained oblique than the spine. Across 5 seasons of professional baseball, 996 oblique injuries cost about 3 weeks each, most during batting or pitching; and in one high school baseball player, an oblique injury where it joins the back's connective tissue was felt as one-sided low back pain after a twisting movement and settled with 7 weeks of care. These are throwing and batting athletes, not people doing Russian twists.
Pain low on one side by the dimple can be the sacroiliac joint, thought to cause 10% to 25% of lasting low back pain low down, though no single question, test or scan confirms it. Pain, tingling or numbness spreading below the knee is sciatica, usually from a disc; the NHS says it usually gets better in a few weeks to a few months, and that a slipped disc usually gets better slowly with rest, gentle exercise and painkillers.
Sources 18, 19, 20, 21, 22
The tummy wall, the tailbone and young athletesEmerging evidence
A bulge that gets bigger when you cough, sneeze or strain and smaller when you lie down can be a hernia, which a GP examines; the NHS says a femoral hernia needs treatment in hospital. Rarely, strenuous exercise or even a small twist can cause bleeding into the six-pack muscle: one 54-year-old woman, not on blood thinners, had it after muscle training. That is a single case report.
The tailbone takes your weight as you balance on a hard floor, and the NHS says tailbone pain is often worse sitting; no study links it to Russian twists, so the floor explanation is our reading. In one clinic, 47 of 100 young athletes with back pain had a stress fracture of the spine, against 5 of 100 adults, which is why a teenager's back pain that lasts gets checked.
Sources 23, 24, 25, 26, 27
Thin bones: twist smoothly, leave out the rounded, loaded versionStrong evidence
The UK consensus on exercise for osteoporosis says "Rotation (twisting) movements should be safe if performed smoothly and comfortably", but that movements involving sustained, repeated or end-range bending of the spine should be modified or avoided, and it notes reports of spinal fractures with loaded or repeated bending exercises, including sit-ups. A weighted Russian twist from a rounded V-sit combines those, which is why our move page says leave it out with osteoporosis or a past spinal fracture. It is expert advice, not a trial result.
Source 28
What a scan shows, and when a test mattersStrong evidence
The National Institute for Health and Care Excellence (NICE) says "Do not routinely offer imaging in a non-specialist setting for people with low back pain with or without sciatica". In 3,110 people without back pain, disc bulges showed in 30% of 20-year-olds and 84% of 80-year-olds, so a scan report of a bulging disc doesn't explain pain on its own.
A test matters for the warning signs (an emergency magnetic resonance imaging (MRI) scan for the cauda equina signs), a young athlete whose back hurts arching backwards for more than a couple of weeks, sudden pain with thin bones, a lump that may be a hernia, a painful, growing lump in the tummy wall, and one-sided pain with a fever or burning when you pee.
Sources 29, 30
How it usually goesStrong evidence
No study follows back pain from Russian twists. Across 33 groups of people with new back pain (11,166 people), average pain fell from 52 out of 100 at the start to 23 at 6 weeks, 12 at 26 weeks and 6 at a year. An update of 95 studies found a similar early fall, but in pain that had already lasted months it changed little over a year (very low certainty).
The NHS says back pain usually improves within a few weeks but can last longer or keep coming back, and NHS inform says new back problems should begin to settle within 6 weeks, with the biggest change in the first couple of weeks. No one can promise a date.
Sources 31, 32, 5, 33
