Key takeaways
- The Achilles tendon joins your calf muscles to your heel bone. It is the thickest and strongest tendon in the body.
- A stretch of tendon 2 to 6cm above the heel has a thinner blood supply than the rest. Most tendon pain and most ruptures happen there, and it is why recovery is slow.
- Pain that builds slowly is usually tendinopathy. A sudden snap with the feeling of being kicked in the calf is a suspected rupture and needs same-day assessment.
- Progressive calf loading has the strongest evidence behind it. Rest alone rarely fixes an Achilles.
Run your fingers down the back of your ankle, and you will find a firm, rope-like cord just above the heel. That is the Achilles tendon, the thickest and strongest in the human body.
It also has a flaw. A stretch roughly 2 to 6cm above the heel bone receives less blood than the sections above and below it. That short segment is where most Achilles pain settles and where most ruptures happen. Almost everything else here follows from that one anatomical fact.
This page explains what the tendon is, what goes wrong with it, and what to do about it in the UK. Mr Francesc Malagelada is a fellowship-trained consultant orthopaedic surgeon who treats foot and ankle conditions exclusively, with a PhD in minimally invasive surgical techniques in the foot. If you already know your tendon has torn, Achilles tendon tears and surgery covers that decision in more depth, and there is a separate guide to choosing the right foot and ankle specialist. You can also browse the full range of foot and ankle treatments available.
This is general information and not a substitute for an assessment by a clinician who can examine you.
What it is and what it does
The Achilles connects your two main calf muscles, the gastrocnemius and the soleus, to your heel bone. Its formal name is the calcaneal tendon. In an adult, it is around 15cm long, narrowest about 4cm above the heel, then flaring out to attach across the back of the bone.
Its main job is pointing the foot down. Every step ends with the calf pulling through the Achilles to lift the heel and push you forward. Its less obvious job is braking, controlling how fast your shin travels forwards over a planted foot. Walking downhill uses this heavily, and it is the loading pattern most likely to aggravate an irritated tendon.
The forces are considerable: roughly three to four times body weight in walking, and somewhere between six and twelve times in running and jumping. It copes because it behaves like a spring, storing energy under load and returning it as it recoils. That is also why it needs load to stay healthy. A tendon that is never loaded becomes less tolerant of load, not more.
The blood supply that explains almost everything
Blood reaches the Achilles from the muscle above, the bone below, and the thin sheath along its length. The mid-portion, 2 to 6cm above the heel, sits furthest from all three. Anatomists call this a watershed zone, and it explains four things at once:
- Ruptures cluster there rather than at the muscle or the bone.
- Healing is slow. Recovery is measured in months, not weeks, and that is normal rather than a sign something has gone wrong.
- Pain has a typical location, which is why a clinician will ask you to point with one finger to the sorest spot.
- Rest alone rarely works. A tendon with a modest blood supply relies on controlled loading to stimulate repair.
In clinic, this is the fact that changes how people feel about their own recovery more than any other. Patients often arrive several months in, convinced that slow progress means something has been missed. Far more often it means the tendon is behaving exactly as its blood supply dictates.
The main things that go wrong
Mid-portion tendinopathy is the most common by some distance. Pain and stiffness develop in that watershed band over weeks rather than suddenly, with stiffness for the first few minutes in the morning, easing as you move, then returning after activity. It usually follows a change in load: a training increase, a return to running after time off, a new job on your feet, a switch of footwear.
Insertional tendinopathy sits right at the back of the heel bone where the tendon attaches. It behaves differently and it responds differently. Compression against the bone is part of the problem, so heel-drop exercises below the level of a step and shoes with a hard rigid back often make it worse. Separating this from mid-portion trouble is one of the most useful things an assessment achieves, because the rehabilitation differs.
A rupture is a complete tear, usually in the same zone, during a sudden push-off. Most people describe feeling struck or kicked in the back of the leg, sometimes with an audible snap, and often turn round expecting to find someone behind them. It is most common between 30 and 50, and around 1 in 3 people had no tendon pain at all beforehand.
Ruptures are missed more often than people expect, because walking is still possible afterwards. Mr Malagelada and his fellowship directors published a review article on chronic Achilles ruptures, meaning those picked up weeks or months later, and it remains a reference on how they are managed. A late diagnosis narrows the options, which is the whole argument for having a suspected rupture looked at the same day.
Less commonly, pain at the back of the heel comes from an irritated bursa between tendon and bone, sometimes with a prominent ridge of bone known as a Haglund’s deformity, or from a partial tear in a tendon that was already degenerate.
Seek same-day assessment if
- You felt a sudden snap, pop or blow to the back of your lower leg.
- You cannot push your foot down properly or rise onto your toes on that leg.
- There is a visible gap or dip in the tendon, or the shape of your calf has changed.
- The area is hot, red and swollen, or you feel feverish and unwell.
- In the UK a suspected rupture should go to an urgent treatment centre or A&E the same day, not wait for a routine GP appointment. Early treatment gives more options.
Not sure whether your Achilles needs a specialist?
Mr Francesc Malagelada treats foot and ankle conditions exclusively and consults across four London clinics: OneWelbeck in Mayfair, The Shard at London Bridge, Cromwell Hospital in Kensington and 31 Old Broad Street in the City. Appointments are available in person or by video, at short notice and without a GP referral, and any imaging you need is usually arranged within days.
You can book a consultation directly, or read more about the foot and ankle treatments available first.
Why Achilles problems happen
The commonest cause is not a single event but a mismatch between load and capacity. The tendon is asked to do more than it has been prepared for, and too quickly. Running mileage that jumps in a fortnight, a first season of racket sports after a decade away, a holiday spent walking hills in flat sandals. The tendon is not damaged by use; it is damaged by unfamiliar use.
A few things raise the risk. Tendons become stiffer and less tolerant of rapid loading from the forties onwards. Tight or weak calves and limited ankle movement increase the demand placed on it. So does a sudden switch to shoes with a much lower heel drop, or stiff-backed boots that press on the insertion. Carrying significant extra weight raises the load at every step, and sports demanding sudden acceleration, such as football, squash, badminton and tennis, are the classic setting for a rupture.
One cause is rarely discussed and worth knowing about. Fluoroquinolone antibiotics, including ciprofloxacin and levofloxacin, are associated with tendinitis and rupture, and the Achilles is the tendon most often affected. The MHRA restricted their use in January 2024, advising particular caution in people over 60. If tendon pain starts while you are taking one, stop it and contact the prescriber promptly. Long-term oral steroids weaken tendons too, which is why steroids are not injected into this tendon.
How Achilles problems are diagnosed
Most diagnoses are made by talking and examining, not by scanning. A clinician will ask how the pain started, where exactly it sits and what your activity has looked like over recent months, then look at the shape of both tendons, feel for the tender point, test calf strength and watch you attempt a heel raise on each leg.
For a suspected rupture, the key test is the calf squeeze, also known as the Simmonds or Thompson test. You lie face down, and the calf is squeezed. In an intact tendon, the foot flexes downwards. If the tendon is torn, it barely moves.
Ultrasound is the usual first scan, because it is quick, involves no radiation and can be done while the ankle moves. MRI is reserved for unclear cases or surgical planning. Our guide to what scan do I need for my painful foot? goes into which test suits which problem. One caution: tendon thickening shows up on scans in plenty of people with no pain at all, so the scan supports the clinical picture rather than replacing it.
Treatment: what actually helps
In the first days of a flare, reduce the aggravating activity rather than stopping everything. Swap running for cycling or swimming, put a small heel raise in both shoes, and choose shoes with some heel height and a soft back.
Then load it, because that is the treatment. Progressive calf loading has the strongest evidence of anything available, and it is the part most often skipped. Some discomfort during the exercises is acceptable provided it settles within 24 hours. Insertional pain needs the exercises on flat ground rather than dropping the heel below a step, because compression at the heel bone is part of the problem. That single adjustment is why a supervised programme tends to outperform an exercise sheet from the internet, and it is one reason the practice is run as a multidisciplinary one, with physiotherapy and podiatry alongside the surgical clinic.
Shockwave therapy is sometimes added when a loading programme has stalled. NICE has reviewed it for stubborn Achilles tendinopathy and found the evidence on how well it works to be inconsistent, while raising no major safety concerns, so it is worth considering alongside continued rehabilitation rather than instead of it. Platelet-rich plasma has not been shown to outperform placebo injection for this tendon and is not routinely recommended in the UK.
Surgery is a minority path for tendinopathy, considered when six months or more of well-conducted rehabilitation has failed. Where an operation is needed, small-incision and keyhole foot surgery approaches are used wherever the problem allows. For rupture, the choice between surgical repair and a functional rehabilitation boot is a genuine one and is made with a specialist, weighing age, activity, occupation and the appearance of the tendon ends. Outcomes vary between individuals, and no route guarantees a return to a previous level of sport.
How long recovery takes
Honest timeframes prevent a lot of anxiety, and Achilles timeframes are longer than most people expect. Mild, recent tendinopathy is often noticeably better within 6 to 12 weeks of consistent loading work. Longstanding cases commonly take three to six months and progress unevenly rather than in a straight line. Insertional problems are generally slower than mid-portion ones.
After a rupture, expect around 8 to 12 weeks in a boot with staged progression, several more months of rehabilitation, and a realistic return to competitive sport somewhere between 6 and 12 months.
Achilles assessment and treatment in London
An Achilles problem is worth getting right early, because the tendon’s blood supply means every month of guessing costs you time you cannot get back. Mr Francesc Malagelada is a fellowship-trained consultant orthopaedic surgeon who treats foot and ankle conditions exclusively, holds a PhD in minimally invasive foot surgery, and is a consultant at The Royal London Hospital.
Book an appointment online, or speak to a specialist about which route makes sense for your tendon.
Frequently asked questions
Can you walk with a torn Achilles tendon?
Often yes, which is why ruptures are missed. Other muscles can still move the foot enough to walk, but push-off is weak or absent, and you will not be able to rise onto your toes on that leg. If you felt a sudden snap, get it assessed the same day even if you can walk on it.
Does an Achilles tendon heal on its own?
Tendinopathy improves with the right loading programme rather than with rest alone, and most people recover well without surgery. A complete rupture does not simply knit back to full function. It needs either surgical repair or a structured protocol in a boot, decided with a specialist.
Should I stretch a sore Achilles tendon?
Strengthening helps more than stretching. Gentle calf stretching can be part of the plan for mid-portion pain, but pain at the heel attachment is often made worse by stretches that push the heel below the level of a step. Get the diagnosis first.
Can I keep running with Achilles pain?
Sometimes, at reduced volume, if the pain stays mild during the run and settles within 24 hours. If it is worse the next morning, the load was too high. Pain that has been there for more than a few weeks needs assessment before you push on.
Which specialist should I see for Achilles pain in the UK?
Start with a physiotherapist, and in most areas you can refer yourself to NHS physiotherapy without a GP appointment. See a GP if the cause is unclear, if several joints are affected, or if you have recently taken a fluoroquinolone antibiotic. A suspected rupture should go to an urgent treatment centre or A&E, and an orthopaedic foot and ankle surgeon is the right specialist for rupture or surgical questions.
References
- NHS inform, Achilles tendinopathy – https://www.nhsinform.scot/illnesses-and-conditions/muscle-bone-and-joints/leg-and-foot-problems-and-conditions/achilles-tendinopathy/
- NICE Clinical Knowledge Summaries, Achilles tendinopathy – https://cks.nice.org.uk/topics/achilles-tendinopathy/
- NICE, Extracorporeal shockwave therapy for refractory Achilles tendinopathy (IPG571) – https://www.nice.org.uk/guidance/ipg571
- MHRA Drug Safety Update, Fluoroquinolone antibiotics: must now only be prescribed when other commonly recommended antibiotics are inappropriate – https://www.gov.uk/drug-safety-update/fluoroquinolone-antibiotics-must-now-only-be-prescribed-when-other-commonly-recommended-antibiotics-are-inappropriate
- British Orthopaedic Foot and Ankle Society, patient information – https://www.bofas.org.uk/patient-information