How to strengthen your hamstrings: hinges, curls and Nordic curls, how often and how heavy, for running and sprinting, and when hamstring pain needs a different plan

Train both jobs

A hinge (bridges, Romanian deadlifts) for the hip and a curl (seated leg curls, slider curls, Nordic curls) for the knee, every week. The long hamstrings cross both joints, and each kind of exercise favours different parts of them.

Sources 1, 2

Squats aren't enough

Full and half squats didn't grow the hamstrings in a 10-week trial, and squats and hip thrusts barely did in another. Add a hinge and a curl.

Sources 3, 4

The moves with the best evidence

Slow Romanian deadlifts and Nordic curls each grew the hamstrings by about 10% in 6 weeks, and seated leg curls grew them more than lying curls: 14% against 9% in 12 weeks.

Sources 5, 1

Nordic curls and injuries

Programmes that include the Nordic were linked with about half as many hamstring injuries. Trials of the Nordic alone point the same way but are inconclusive, and the benefit showed only with good adherence.

Sources 6, 7, 8

A little goes a long way

Low Nordic volumes built as much strength as high ones. Start with 1 or 2 sets of 3 to 5 slow lowers and build to 2 or 3 sets of 3 to 6 twice a week, as our Nordic curl guide suggests, with 2 or 3 sets of 8 to 12 hinges and curls inside strength work on 2 or more days a week.

Sources 9, 10, 11

Stretching won't protect you, and pain needs its own plan

Stretching hasn't been shown to prevent hamstring strains. A sudden pop, a big bruise, pain at the sitting bone or pain spreading below the knee isn't a strengthening job: see the warning signs below.

Sources 12, 13

The muscles

Three hamstrings run from your sitting bone down the back of your thigh: the biceps femoris on the outside, and the semitendinosus and semimembranosus on the inside. The biceps femoris also has a short head that starts on the thigh bone and crosses only the knee. The long muscles cross both the hip and the knee, so they straighten your hip and bend your knee. Our hamstrings and biceps femoris pages have the anatomy.

Source 1

Two jobs, two kinds of exercise

Hinges and bridges train the hip job, and in muscle activity and MRI scan studies they favoured the biceps femoris long head and the semimembranosus. Curls and the Nordic train the knee job and favoured the semitendinosus. In a 9-week trial, stiff-leg deadlifts grew the semimembranosus most and Nordics the semitendinosus. That's why our Romanian deadlift and leg curl guides ask for one of each a week.

Sources 2, 14

Why seated curls

Sitting bends your hip and stretches the long hamstrings, which is the likely reason seated leg curls grew them more than lying curls in a trial. The short head, which doesn't cross the hip, grew about the same on both.

Source 1

Lowering strength

Eccentric (lowering) strength is your hamstrings' strength while they lengthen under load, as when they brake the swinging leg in a sprint. In elite football, players with low lowering strength and short biceps femoris fibres had more strains. Nordic curls and slow lowering build it.

Sources 15, 16, 17

How people differ

A previous strain and older age are the strongest risk factors for a hamstring strain: any previous strain went with 2.7 times the risk, and a recent one 4.8 times. How far you can hinge depends on your hamstrings, not your effort, so stop the Romanian deadlift where they stop you, usually around knee height to mid-shin, as our RDL guide says. The Nordic is harder the taller and heavier you are, because the lever is longer (our reading), so the band-assisted version is the way in.

Source 18

Strength, not size

This guide is about strength for everyday life, running and sport. Our bigger legs guide covers size, and our hamstring strain guide covers recovering from an injury.

Training at long lengths grew moreEmerging evidence

In 20 untrained adults training one leg seated and one lying, 5 sets of 10 twice a week for 12 weeks, the whole hamstrings grew 14% with seated curls against 9% with lying curls. In 42 young men over 12 weeks, seated curls with the hip bent further and slow lowering grew the hamstrings 18%, against 11% for Nordic curls, and the biceps femoris long head 19% against 5%.

Sources 1, 19

Slow Romanian deadlifts and Nordics both workEmerging evidence

In 32 adults (15 of them women) training twice a week for 6 weeks with a 4 to 6 second lowering, slow Romanian deadlifts and Nordic curls each lengthened the long head's fibres by about 9% and grew the hamstrings by about 10%, with no difference between them. In 36 untrained adults over 9 weeks, Nordics grew the hamstrings 11.4% and stiff-leg deadlifts 7.0%, each favouring a different muscle.

Sources 5, 14

Squats barely grow the hamstringsEmerging evidence

In 17 men doing full or half squats twice a week for 10 weeks, the thigh muscles that straighten the knee grew about 5%, but the hamstrings didn't change. In 34 untrained adults, 9 weeks of squats or hip thrusts gave the hamstrings little to no growth, and the leg press grew them about 3% in 12 weeks in another trial.

Sources 3, 4, 20

Low Nordic volumes build strengthEmerging evidence

In 19 elite youth footballers, one set raised lowering strength as much as four (11.3% against 11.4%). In 20 men, 8 Nordics a week kept building fibre length and strength as well as a higher volume. Across 42 studies, volume didn't predict strength gains, with typical effective doses of 29 to 64 reps a week. In one small trial, twice a week beat once a week for Nordic strength.

Sources 9, 17, 21, 10, 22

Fibre length may need more, and fadesMixed evidence

In 11 soccer studies, only higher volumes (about 2 to 3 sets of 8 to 12, 2 or 3 times a week) changed fibre length. In two trials, fibre gains went back within 2 weeks of stopping, while strength held for at least 4 weeks in one. So keep a weekly session.

Sources 23, 17, 5

A past strain and age matter mostStrong evidence

Across 78 studies of 8,319 strains, older age and a previous hamstring strain were the strongest risk factors for a new one: a previous strain went with 2.7 times the risk, and a recent one 4.8 times.

Source 18

Low lowering strength and short fibresEmerging evidence

In 210 elite Australian footballers, low Nordic strength went with 2.7 to 4.3 times the risk of a strain, and in 152 elite soccer players, low strength and short long-head fibres each went with about 4 times the risk. Risk factors like these aren't proof that changing them prevents strains.

Sources 15, 16

The guidelinesStrong evidence

The World Health Organization (WHO) and the NHS ask adults for muscle-strengthening activity working all the major muscle groups, the legs and hips included, on 2 or more days a week. In the 2026 American College of Sports Medicine (ACSM) overview of 137 reviews, strength rose most with heavier loads, a full range, 2 to 3 sets and 2 or more sessions a week.

Sources 11, 24, 25

How often

Train each job once or twice a week, inside strength work on 2 or more days a week. Do Nordics twice a week while you build up, then keep at least one session a week, as our Nordic curl guide suggests (editorial).

Source 11

Sets and reps

Romanian deadlifts: 3 sets of 8 to 10, lowering for about 3 seconds, as our RDL guide and hamstring workout use. Seated leg curls: the move page's dose is 2 to 3 sets of 8 to 12, stopping with 2 or 3 reps in reserve (our editorial starting point); our hamstring workout uses 3 sets of 10 to 12. Nordic curls: 1 or 2 sets of 3 to 5 slow lowers for the first week or two, then 2 or 3 sets of 3 to 6 (our Nordic curl guide's editorial starting point).

How hard

Stop hinges 2 or 3 reps short of failure, which our guides call 2 or 3 RIR (reps in reserve: how many more reps you could have done). The last set of curls can go to 0 to 2, as our plans' notes say. In Nordics, lower as slowly as you can, as far as you can control, then catch yourself on your hands.

Rest

About 90 seconds to 2 minutes between Romanian deadlift sets, and 60 to 90 seconds for curls, as our plans' notes say.

Progress

Add reps until every set reaches the top of its range, then add the smallest weight step, as our plans' notes say. Nordics progress by lowering further and more slowly, then moving to the next step of the ladder.

How long

Muscle and fibre changes showed within 6 to 12 weeks in trials, and the football programmes built up over 10 to 13 weeks, then carried on. Fibre-length gains faded within 2 weeks of stopping, so keep a weekly session going.

Sources 5, 1, 26, 27, 17

Soreness after Nordics

Your first Nordic sessions can leave your hamstrings very sore for a few days, and much less so a few weeks later, as our Nordic curl guide explains. Start with very few reps.

Coming back from a strain: the pain rule

Mild to moderate discomfort that you find tolerable is fine during exercise; in a trial, working that way did no harm and recovered more strength. In the lengthening exercises (the Extender and the Diver), stop just before pain. Sharp pain, or a limp afterwards, means back off for a session or two.

High hamstring tendinopathy has its own rule, from its largest trial: up to 4 out of 10 during exercise, and no more than 2 points worse the next day. Its guide explains it.

Programmes that include the NordicEmerging evidence

Programmes that include the Nordic were linked with about half as many hamstring injuries: a risk ratio of 0.49 across 15 studies of 8,459 athletes (0.52 in the 8 randomised trials), and 0.49 across 5 soccer studies.

Sources 6, 28

The Nordic on its ownMixed evidence

Trials of the Nordic alone point the same way but are inconclusive. A re-analysis of only the trials that tested the Nordic itself gave a risk ratio of 0.59, anywhere from 0.27 to 1.29, mostly from trials at high risk of bias. A 2026 network analysis of 11 football trials (9,282 players) gave 0.78 for the Nordic alone, at very low certainty, and 0.55 for the FIFA 11+ warm-up.

Sources 7, 29

The two biggest trialsEmerging evidence

In 942 Danish male footballers, a 10-week build-up and then a weekly session in season gave 3.8 hamstring injuries per 100 player seasons against 13.1, and repeat injuries fell most. In 579 Dutch amateur players, 25 sessions over 13 weeks gave 0.25 injuries per 1,000 hours against 0.8.

Sources 26, 27

Only if you keep doing itEmerging evidence

Across 15 football trials (7,465 players), prevention programmes cut hamstring strains when players did 75% or more of the sessions (risk ratio 0.36), but showed no clear benefit below that (0.92), at low certainty. Earlier reviews found the same pattern.

Sources 8, 30, 31

What we take from it

Do Nordics for the lowering strength they build, alongside sprinting and the rest of your training, and keep them going through the season. Our Nordic curl guide has the full trial detail.

Where strains happenStrong evidence

In men's professional football, hamstring injuries rose from 12% of all injuries in 2001 to 24% by 2022, mostly while running or sprinting, and 18% were repeat injuries.

Sources 32, 33

Sprinting itselfEmerging evidence

In small trials, sprint training lengthened the biceps femoris long head's fibres as much as Nordics or more (16% against 7% in 6 weeks, in small groups of footballers), raised lowering strength in teenagers and made athletes faster. These are small studies of muscle fibre length and strength: no trial has measured whether sprint training prevents hamstring injuries.

Sources 34, 35, 36, 37

Nordics and speedEmerging evidence

In amateur footballers, Nordics made 10 m sprints 0.047 seconds faster in a trial: a small change, in the right direction.

Source 38

After a strainEmerging evidence

Lengthening-type exercises returned elite footballers in a mean of 28 days against 51. Rehab that allowed tolerable pain returned players no sooner than pain-free rehab (17 against 15 days, not a significant difference) but recovered 15% more strength. Our hamstring strain guide has the stages.

Sources 39, 40

If you sprint

Keep sprinting in training, building from skips and 60 to 70% efforts over several sessions, as our hamstring strain guide's return stage does, alongside 2 short strength sessions a week (our suggestion). Our strength training plan for runners and our strength and hamstring workout for sprinters have the sessions, and our sprint faster guide covers speed.

At home

Bridges, single-leg bridges and slider curls with a towel on a smooth floor, then slider lowers, band-assisted Nordics and Nordics with your heels hooked under something heavy that can't move, or held by a partner. Single-leg Romanian deadlifts holding a backpack cover the hinge. Our Nordic curl progression puts these in order.

In the gym

Romanian deadlifts with a barbell or dumbbells, the seated leg curl, and the glute-ham raise or a Nordic bench if there's one. Our leg curl guide covers the machines.

After 60

The same two jobs, made gentler: bridges, a supported hinge or a light Romanian deadlift, and seated or standing curls, 2 or 3 sets of 10 to 15 (our editorial starting point). Nordics are optional. Balance work matters more for falls, and our exercise for older adults and leg strengthening guides have it.

A strain

A sudden sharp pain at the back of the thigh while sprinting or stretching is often a strain. Our hamstring strain guide starts gentle loading within days and brings Nordics back late, in stages.

Pain at the sitting bone

Deep pain low in the buttock with sitting and running that is not settling: possible high hamstring tendinopathy, which has its own guide.

Nordic curls and deep hinges wait, as our Nordic curl and Romanian deadlift guides say.

Pain spreading below the knee

Pain in the back of the thigh with tingling, numbness, or pain spreading below the knee: it may come from the back (sciatica).

Our sciatica guide covers it.

Pain behind the knee on the leg curl

Our knee pain on the leg curl guide covers it, with the changes to try.

After ACL (anterior cruciate ligament) surgery with a hamstring graft

Resisted hamstring curls wait until your rehab team allows them, as our leg curl guide says. Our ACL surgery guide covers the stages.

A past strain

A past strain is the strongest risk factor for another, so Nordics and sprint work matter more for you. Finish the stages in our hamstring strain guide first.

Back pain or a disc problem

While symptoms are irritable, reduce the load and range of heavy hinges, then rebuild, as our Romanian deadlift and herniated disc guides say. Stop for pain that travels down a leg.

Osteoporosis

With osteoporosis or a past spinal fracture, avoid repeated or loaded deep rounding of the back, and bend from the hips. The osteoporosis guide covers impact and lifting.

Pregnancy

Use the seated or standing curl rather than lying face down on a curl bench, as our leg curl guide suggests, and swap bridges and slider curls on your back for standing or side-lying moves in later pregnancy (our suggestion, following the NHS advice our plans give).

A torn hamstring or tendon

Same day: a pop near the sitting bone, a large bruise high on the back of the thigh, or you cannot put weight on the leg. The tendon may have pulled away from the bone, which needs assessing before you start these exercises.

A hamstring injury

Get help from NHS 111 if you think you've injured your hamstring and it's very painful, or the pain is getting worse; there's a large amount of swelling or bruising, or the swelling or bruising is getting worse; it hurts to walk or stand using the injured leg; your leg feels very stiff or is difficult to move; it's not feeling any better after treating it yourself; or you have a very high temperature or you feel very hot, but also cold and shivery, which could be signs of an infection.

Source 41

Back pain with leg symptoms

Call 999 or go to A&E: loss of feeling or numbness around the genitals or bottom, new trouble peeing or controlling your bladder or bowels, changes in genital sensation during sex or problems with erections or orgasm, or pain, tingling, weakness or numbness in both legs. These are signs of cauda equina syndrome, which needs treating in hospital urgently. Don't drive yourself.

See a GP if pain spreading down a leg hasn't improved after a few weeks of home treatment, is getting worse or stops your normal activities. Sciatica on both sides, or weakness or numbness in both legs that's severe or getting worse, is a 999 call or a trip to A&E.

A foot that drops or catches

Same day (urgent GP appointment or NHS 111): new difficulty lifting the front of your foot or toes (foot drop), or a foot that slaps down or catches as you walk, especially if it is getting worse. Weakness in both legs, or with numbness around the genitals or bottom or bladder or bowel changes, is the 999 emergency above.

A clot in the leg

Same day (urgent GP appointment or NHS 111): throbbing pain in one leg (rarely both), usually the calf or thigh; swelling in one leg (rarely both); red, blue or darkened skin around the painful area, which may be harder to see on brown or black skin; or swollen veins. It could be a blood clot (deep vein thrombosis, DVT), which is more likely while you're moving about much less than usual or after a hospital stay.

Also call 999 for pain and swelling in one leg with breathlessness or chest pain: it can be a blood clot that has reached the lungs.

Source 42

Knee symptoms during curls

Get advice from NHS 111 now: the knee locks, gives way or clicks painfully. Painless clicking is normal.

After unusually hard training

Call NHS 111 (in the US, your doctor or urgent care) for severe muscle pain and weakness with dark (cola-coloured) or reduced urine after unusually hard training. This can be rhabdomyolysis, which can harm the kidneys and needs prompt care.

Stop and get medical help

If you get chest pain or pressure, feel faint or dizzy, are unusually breathless, or your heart races or beats irregularly during exercise, as our plans advise.

Call 999 (911 in the US)

For chest pain that comes on suddenly and doesn't go away, feels tight or like squeezing, spreads to your arms, neck, jaw, stomach or back, or comes with sweating, feeling sick, light-headedness or breathlessness; severe difficulty breathing; someone who faints while exercising; palpitations that don't go away, or come with chest pain, shortness of breath or feeling faint; or a headache that starts suddenly and is extremely painful, especially while lifting or straining, or comes with numbness or weakness, difficulty speaking or loss of vision. The NHS says a bleed on the brain may be more likely when lifting something heavy. Don't drive yourself to A&E.

Ask for an urgent GP appointment or call NHS 111

Ask for an urgent GP appointment or get help from NHS 111 for a headache that's triggered or made worse by coughing, sneezing, bending down or exercising. In the US, contact your doctor or urgent care.

During any session

Stop straight away if you feel any pain or become unwell, the NHS says, and contact 111 if your symptoms worry you or don't go away.

A dull ache in your muscles for a day or two after something new is normal. Joint pain that's sharp, gets worse during a set or lingers into the next day means switching to the easier option, and seeing a GP or physiotherapist if it carries on (our plans' rule). Our muscle soreness guide has more.

Check first

Speak to your GP first if you haven't exercised for some time or have medical conditions or concerns, as the NHS advises. Get advice before heavy lifting or hard straining work if your blood pressure is uncontrolled, or you have heart disease or chest pain when you're active, a pacemaker or defibrillator, diabetic eye disease, glaucoma, a hernia, recent eye or tummy surgery, or you're pregnant, as our breathing guide lists. After a recent shoulder dislocation or shoulder surgery, follow our shoulder dislocation guide or your surgical team first.

Speak to a GP first if you haven't exercised for some time, or if you have a medical condition or concerns. Get advice first, too, if you have a health problem, an injury or symptoms, have recently had a heart attack or an operation, or are pregnant or have recently given birth.

Source 24

Hernia

See a GP if you think you have a hernia, a bulge or lump that may get bigger when you strain and smaller when you lie down. Get help from NHS 111 if you have a hernia and pain in or around it, a bloated tummy, you feel or are sick, you're vomiting blood or your vomit looks like coffee grounds, you're constipated, you have a high temperature or feel hot, cold or shivery, or you've suddenly become confused. Call 999 or go to A&E for a femoral hernia (a small lump at the top of your thigh, in your groin) with very bad tummy pain, sickness, being unable to fart or poo, a high temperature or sudden confusion.

Sources 43, 44

"Stretching prevents hamstring strains"Mixed evidence

No trial shows it. Stretching didn't lower sports injuries overall in 25 trials of 26,610 people, while strength training did; a flexibility programme didn't cut strains in elite soccer, while lowering work did; and reviews of hamstring stretching found only poor-quality studies. Stretch if you like how it feels; strengthen to protect.

Sources 12, 13, 45, 46

"Squats train the whole leg"Emerging evidence

Not the hamstrings: full and half squats didn't grow them in 10 weeks, squats and hip thrusts barely did in 9, and the leg press managed about 3% in 12. In a squat the hamstrings shorten at the hip as they lengthen at the knee, so they change length little (our reading). Add a hinge and a curl.

Sources 3, 4, 20

"Nordic curls halve hamstring injuries"Mixed evidence

Programmes that include them were linked with about half as many hamstring injuries, but trials of the Nordic alone are inconclusive, and the benefit showed only with good adherence. Do them for the lowering strength they build, as part of a wider programme.

Sources 6, 7, 29, 8

"You need lots of Nordic reps"Emerging evidence

For strength, no: in two small trials, a single set, or 8 reps a week, built as much as far more. Fibre length may need more.

Sources 17, 9, 21, 23

"Leg curls are all you need", or "RDLs are all you need"Emerging evidence

Each favours different hamstring muscles, and seated curls grew the long hamstrings more than lying ones. Ordinary curls didn't build lowering strength in 10 weeks while Nordics did, as our leg curl guide explains. Do one hinge and one curl.

Sources 2, 14, 1

"Weak or tight hamstrings cause back pain and bad posture"Mixed evidence

We found no study showing that weak hamstrings cause back pain or posture problems. Tight hamstrings went with later back pain in one study of 296 teenage baseball players, but that's a link in one group, not proof of cause.

Source 47

"Strong hamstrings mean you won't get injured"Emerging evidence

Strength helps, but a previous injury and age matter most, and sprinting is where most strains happen. Keep sprinting in training if your sport has it (our reading).

Sources 18, 32