Overview
dorsiflexion
Bringing the toes toward the shin; restricted range here is a common driver of lower-limb problems.Interesting facts
- • The Achilles experiences forces of six to eight times body weight during running push-off, more than any other tendon.
- • Its fibres spiral roughly 30 to 150 degrees as they descend, contributing to strength but also concentrating stress at the mid-portion where degeneration typically occurs.
- • Tendon returns stored elastic energy with remarkably little loss, and this recycling accounts for a substantial fraction of running economy.
- • The talus has no muscle attachments whatsoever — every ankle movement is produced by muscles acting through tendons that pass over it.
- • Ankle sprains are the most common musculoskeletal injury of all, and a large proportion of people go on to develop persistent symptoms or instability.
- • The Achilles has a relatively poor blood supply in its mid-portion, which is part of why it heals slowly and degenerates there preferentially.
Common misconceptions
- Achilles pain means you should rest until it settles.
Complete rest deconditions the tendon further. Progressive loading is the primary evidence-based treatment, and the landmark trials that established this deliberately had patients exercise into discomfort. - Tendinopathy is inflammation, so anti-inflammatories are the treatment.
Chronic tendinopathy is predominantly degenerative rather than inflammatory — 'tendinitis' is a misnomer. NSAIDs may relieve pain but do not treat the underlying tissue change and may blunt the adaptation loading produces. - A sprained ankle just needs rest until you can walk on it.
This is why so many sprains become chronic. Inadequate rehabilitation leaves proprioceptive and strength deficits, and around a third to a half of people develop persistent instability. Balance training measurably prevents recurrence. - Stretching before running prevents Achilles injury.
Static pre-exercise stretching has not been shown to reduce injury rates. Progressive strength and sensible load management have far better evidence. - You need surgery for a ruptured Achilles.
Modern functional rehabilitation has narrowed the gap considerably. Non-surgical management with early controlled loading produces comparable outcomes for many patients, though re-rupture rates are somewhat higher. - Cortisone injections help Achilles problems.
Corticosteroid injection around the Achilles is generally avoided because of the association with tendon rupture; it provides short-term relief at the cost of worse long-term outcomes.
Anatomy & how it works
A spiralling tendon converging from two calf muscles onto the heel, above a hinge joint stabilised by distinct ligament groups.
Achilles tendon
The combined tendon of gastrocnemius and soleus, inserting on the calcaneus; the strongest tendon in the body.
Mid-portion
The region 2–7 cm above the insertion, with the poorest blood supply and the commonest site of tendinopathy.
Insertional region
Where the tendon meets the heel bone, with associated bursae; insertional tendinopathy behaves differently and dislikes compression.
Paratenon
The sheath surrounding the tendon, which can become inflamed independently of the tendon itself.
Talocrural joint
The true ankle hinge between tibia, fibula and talus, producing dorsiflexion and plantarflexion.
Subtalar joint
Between talus and calcaneus, producing inversion and eversion — the movement involved in most sprains.
Lateral ligament complex
Anterior talofibular, calcaneofibular and posterior talofibular ligaments; the anterior talofibular is injured in most sprains.
Deltoid ligament and syndesmosis
The medial ligament and the tibiofibular connection above the joint; high ankle sprains involve the latter and take far longer to heal.
Retrocalcaneal bursa
The fluid sac between tendon and heel bone; inflamed in insertional problems and aggravated by shoe pressure.
dorsiflexion
Bringing the toes toward the shin; restricted range here is a common driver of lower-limb problems.Primary functions
- • Transmitting calf muscle force to the heel for push-off
- • Storing and returning elastic energy during walking, running and jumping
- • Allowing the ankle to dorsiflex and plantarflex through the gait cycle
Secondary functions
- • Absorbing and dissipating landing forces
- • Providing proprioceptive feedback for balance and postural control
- • Permitting inversion and eversion to adapt to uneven ground
- • Contributing to the calf muscle pump that drives venous return
Across a lifetime
- Development
- Achilles length and ankle range develop with walking and running; persistent toe-walking beyond the toddler years suggests calf tightness needing assessment.
- Childhood
- Sever's disease — traction irritation at the heel growth plate — is common in active children and adolescents and settles as the growth plate matures.
- Adulthood
- Achilles tendinopathy peaks in the thirties and forties, particularly in recreational runners increasing volume. Acute rupture is classically associated with intermittent explosive sport in this same age range.
- Later life
- Tendon stiffness and elasticity both decline, reducing push-off power and shortening stride — a change that directly slows gait speed, itself a strong predictor of health outcomes. Ankle proprioception also declines, raising falls risk.
- Sex differences
- Achilles rupture is substantially more common in men. Habitual high-heel wear, more common in women, shortens resting calf and Achilles length over time and reduces dorsiflexion range.
Body connections
This region determines how well you move, and by extension how much you move. Achilles and ankle problems are among the most common reasons active people stop exercising, and the resulting inactivity carries its own cardiovascular and metabolic cost. In later life, ankle push-off power and proprioception are direct contributors to gait speed and falls risk — two of the strongest predictors of continued independence. The Achilles is also the clearest example in musculoskeletal medicine of a principle that generalises widely: connective tissue gets stronger by being loaded, and weaker by being protected.
Body connections
How this links to the rest of you
The Achilles is the shared tendon of gastrocnemius and soleus, so calf strength and the tendon's load tolerance are inseparable.
The Achilles connects functionally to the plantar fascia through the heel, so restriction in one alters loading in the other.
Restricted ankle dorsiflexion increases knee valgus during landing and squatting, raising anterior knee and ACL loading.
Tendon and fascia share collagen structure, slow adaptation timescales and the same loading-based rehabilitation principles.
Limited ankle range changes squat and gait mechanics, shifting compensatory load up the chain to the lumbar spine.
Calf contraction through the Achilles drives the muscle pump for venous return; immobilisation in a boot or cast raises clot risk substantially.
The posterior chain functions as a coordinated unit in running, and gluteal weakness increases distal loading on the calf and Achilles.
How lifestyle changes it
Exercise
Tendon responds well to heavy slow resistance and plyometric loading, but adapts far more slowly than muscle. Most Achilles injuries are load-progression errors — the muscle can handle more than the tendon has adapted to.
Nutrition
Adequate protein and vitamin C support collagen turnover. Gelatin or collagen peptides with vitamin C before loading show early promise for tendon adaptation specifically.
Hydration
Frequently cited for cramp prevention, though the evidence for that specific claim is weaker than commonly assumed.
Sleep
Collagen synthesis is concentrated during sleep, so chronic restriction plausibly slows tendon adaptation and recovery from loading.
Stress
Mainly indirect, through reduced training consistency and impaired recovery quality.
Ageing
Tendon stiffness and elastic energy return both decline, reducing push-off power and stride length. Ankle proprioception deteriorates, contributing to falls.
Environment
Habitual heeled footwear shortens resting calf and Achilles length. Abrupt changes in footwear drop, running surface or terrain are common triggers for Achilles problems.
Genetics
Variants in collagen genes influence tendon injury susceptibility. Fluoroquinolone antibiotics carry a recognised association with tendon rupture, and family history of rupture is relevant.
Symptoms & conditions
Common symptoms
Common conditions
Rare conditions
- • Chronic exertional compartment syndrome of the lower leg
- • Osteochondral lesion of the talus
- • Tarsal tunnel syndrome
- • Haglund's deformity
- • Os trigonum syndrome
- • Charcot arthropathy of the ankle in diabetes
Acute & chronic problems
- • Lateral ankle sprain
- • High ankle (syndesmotic) sprain
- • Complete Achilles tendon rupture
- • Ankle fracture
- • Plantaris tendon rupture mimicking a calf tear
- • Peroneal tendon dislocation
- • Mid-portion Achilles tendinopathy
- • Insertional Achilles tendinopathy
- • Chronic ankle instability after inadequately rehabilitated sprain
- • Retrocalcaneal bursitis
- • Post-traumatic ankle osteoarthritis
- • Restricted dorsiflexion limiting squat and gait mechanics
Early warning signs
- • Achilles stiffness in the morning that eases with walking
- • Tendon pain that warms up during a run then returns afterwards
- • Localised thickening or a tender nodule in the tendon
- • Reduced ability to perform single-leg heel raises
- • The ankle giving way on uneven ground
- • Needing to lift the heels in order to squat
Risk factors
- • Rapid increases in running, jumping or hill volume
- • Previous Achilles injury or ankle sprain
- • Restricted ankle dorsiflexion
- • Abrupt change in footwear drop or running surface
- • Fluoroquinolone antibiotic use
- • Increasing age
- • Diabetes and inflammatory arthritis
Protective factors
- • Regular heel raises with both straight and bent knees
- • Gradual load progression, respecting that tendon adapts more slowly than muscle
- • Balance and proprioceptive training after any ankle sprain
- • Maintaining ankle dorsiflexion range
- • Varying footwear heel drop rather than always using the same
- • Full rehabilitation of sprains rather than returning when pain settles
Optimise & recover
Prevention
- • Do calf raises with both straight and bent knees at least twice weekly — soleus is heavily loaded in running and routinely under-trained
- • Increase running and jumping volume gradually; tendon adaptation lags muscle adaptation by weeks to months
- • Maintain ankle dorsiflexion range so the tendon and calf are not chronically shortened
- • After any ankle sprain, complete a balance training programme — it substantially reduces recurrence and is the step most often skipped
- • Change footwear drop gradually rather than switching abruptly between shoe types
- • Add elastic loading such as pogo hops once a strength base exists, to train tendon stiffness
Recovery
- • For Achilles tendinopathy, load rather than rest: start with isometric holds for pain relief and progress to heavy slow resistance
- • Commit to at least twelve weeks — the main determinant of success in tendon rehabilitation is whether the programme is continued long enough
- • In insertional tendinopathy, avoid loading into full dorsiflexion early, since compression at the insertion aggravates it
- • After a sprain, restore full range and single-leg balance before returning to sport, not just the ability to walk without pain
- • After rupture, follow the functional rehabilitation protocol closely — early controlled loading is what has narrowed the gap between surgical and non-surgical outcomes
Achilles tendinopathy is the clearest demonstration in musculoskeletal medicine that loading beats rest. Alfredson's 1998 eccentric heel-drop protocol showed that painful loading resolved chronic cases that had been managed with rest for years, and subsequent work has found heavy slow resistance to be equally effective and often better tolerated. Both require twelve weeks or more, because collagen remodels slowly. For ankle sprains, the equivalent evidence concerns proprioception: balance and neuromuscular training after a sprain reduces recurrence substantially, yet most sprains are still managed with rest alone — which is why chronic ankle instability is so common.
Movement library
- Beginner
Knee-to-wall dorsiflexion drill
Both a measurable assessment and a mobility exercise for the ankle range that governs squat and gait mechanics.
- Beginner
Ankle circles and alphabet drills
Restores range and proprioceptive input early after a sprain, before weight-bearing work.
- Beginner
Weight-bearing dorsiflexion mobilisation
Loaded ankle rocking to restore the talus glide needed for full dorsiflexion.
- Beginner
Straight-knee heel raise
Loads gastrocnemius, the primary explosive plantarflexor.
- Beginner
Bent-knee (seated) heel raise
Isolates soleus, which carries greater load than gastrocnemius during running and is commonly under-trained.
- Intermediate
Heavy slow resistance calf raise
Slow, heavily loaded raises with strong trial evidence in Achilles tendinopathy, comparable to eccentric protocols and often better tolerated.
- Intermediate
Eccentric heel drop (Alfredson protocol)
The original evidence-based tendinopathy programme — twice daily, into discomfort, for twelve weeks.
- Beginner
Single-leg balance progression
Eyes open to eyes closed to unstable surface; the best-evidenced intervention for preventing recurrent ankle sprain.
- Beginner
Peroneal strengthening with resistance band
Strengthens the eversion that resists the inversion mechanism of lateral ankle sprain.
- Advanced
Pogo hops and plyometric loading
Trains tendon stiffness and elastic energy return; introduce only once heavy strength work is tolerated.
- Beginner
Straight-leg calf stretch against a wall
Lengthens gastrocnemius, most relevant for habitual heeled-footwear wearers.
- Beginner
Bent-knee calf stretch
Targets soleus and deeper structures around the Achilles.
- Beginner
Avoid deep dorsiflexion stretching in insertional tendinopathy
Compression at the tendon insertion aggravates symptoms; keep early loading out of end-range dorsiflexion.
Calf and Achilles massage eases muscular tightness in the short term and can improve comfort enough to permit loading. It does not treat tendon degeneration. Avoid direct pressure over the tendon insertion in insertional tendinopathy, where compression is precisely the aggravating factor.
Habits worth building
- • Do heel raises while waiting — the calf tolerates and benefits from high frequency
- • Practise single-leg balance daily while brushing your teeth; it is free proprioceptive training
- • Rotate between shoes with different heel drops rather than wearing one type exclusively
Nutrition, devices & products
Tendon has a slow metabolism and a modest blood supply, so nutrition supports rather than drives adaptation — loading is the primary stimulus. What matters is having the substrate available: adequate total protein, and vitamin C, which is an essential cofactor for the enzymes that stabilise collagen. The most interesting recent finding is about timing: gelatin or collagen peptides taken with vitamin C roughly an hour before loading exercise increases markers of collagen synthesis, presumably because it delivers amino acids to a poorly perfused tissue at the moment the loading signal arrives.
Foods to prioritise
- • Adequate protein, around 1.6 g per kg body weight when training or rehabilitating
- • Vitamin C, essential for collagen cross-linking
- • Gelatin or collagen peptides timed about an hour before loading sessions
- • Sufficient carbohydrate to support running and jumping volume
- • Vitamin D, which supports muscle function and load-sharing
Foods to limit
- • Alcohol, which impairs collagen synthesis and recovery from loading
- • Prolonged courses of high-dose NSAIDs during tendon rehabilitation, which may blunt the adaptation you are trying to produce
- • Fluoroquinolone antibiotics where alternatives exist, given the tendon rupture association — a clinician decision
- • Sustained low energy intake, which suppresses tissue remodelling
| Supplement | Evidence | Note |
|---|---|---|
| Collagen peptides or gelatin with vitamin C | Emerging | Increases collagen synthesis markers when taken roughly an hour before loading; clinical outcome data are still developing but the risk is negligible. |
| Creatine monohydrate | Strong | Supports the strength and power development that underpins calf and tendon loading capacity, with no direct tendon effect. |
| Vitamin C | Strong | Required for collagen formation; correcting inadequacy matters, but extra beyond sufficiency has no demonstrated benefit. |
| Magnesium | Limited | Widely used for calf cramps, but trials in non-pregnant adults have generally failed to show benefit. |
| Platelet-rich plasma injection | Limited | Repeatedly tested in Achilles tendinopathy without demonstrating benefit over placebo, despite widespread commercial availability. |
Devices & wearables
- • A step or calf raise block for full-range loading
- • Heel lifts as a temporary offloading measure in Achilles tendinopathy
- • Balance boards and wobble cushions for proprioceptive rehabilitation
- • Walking boots and functional braces for rupture and severe sprain management
- • Compression socks for venous symptoms and post-exercise recovery
- • Running watches tracking cadence, volume and load, genuinely useful for the gradual progression tendon requires
- • Force plates for measuring single-leg hop symmetry during return-to-sport testing
Professional treatments
- • Ultrasound imaging of the tendon, including assessment of thickening and neovascularisation
- • Physiotherapy-led progressive loading programmes
- • Extracorporeal shockwave therapy for recalcitrant tendinopathy
- • Functional rehabilitation protocols for Achilles rupture
- • Surgical repair of rupture in selected patients
- • Ankle arthroscopy for impingement or osteochondral lesions
- • Lateral ligament reconstruction for chronic instability
Educational mention only, not a recommendation: Short-course NSAIDs for acute sprain pain, used cautiously in tendon rehabilitation, Topical anti-inflammatories for superficial tendon pain, Corticosteroid injection around the Achilles, generally avoided because of rupture risk, Thromboprophylaxis during lower-limb immobilisation, where clot risk is genuinely raised.
When to seek medical care
Gradual-onset Achilles pain that eases with warm-up usually responds to a progressive loading programme, and twelve weeks is a realistic timeframe. A sudden sensation of being kicked in the back of the leg, with inability to push off or rise onto the toes, suggests rupture and needs prompt assessment — outcomes are better with early management. Treat unilateral calf swelling with warmth and tenderness as possible deep vein thrombosis and seek same-day assessment, particularly after surgery, immobilisation or long travel. After an ankle sprain, inability to bear weight or obvious deformity warrants assessment for fracture.
Seek care promptly if you notice
- • A sudden 'kicked in the leg' sensation with inability to push off or rise onto the toes
- • A palpable gap in the tendon with weak plantarflexion
- • Unilateral calf swelling with warmth and tenderness
- • Calf or ankle symptoms alongside breathlessness or chest pain
- • Inability to bear weight after an ankle injury, or visible deformity
- • A cold, pale or numb foot with calf or ankle pain
- • Ankle pain with fever, spreading redness and feeling unwell
Research & frequently asked questions
Current research
- Loading protocols for Achilles tendinopathy continue to be compared, with heavy slow resistance and eccentric approaches performing similarly well — shifting the question from which protocol to how to sustain adherence for the required twelve weeks.
1
American Journal of Sports Medicine · 1998
Heavy-load eccentric calf muscle training for the treatment of chronic Achilles tendinosis
Landmark study in which recreational runners with chronic Achilles tendinosis returned to pre-injury running after a twelve-week eccentric loading programme, establishing loading over rest.
- Non-surgical management of Achilles rupture with early functional rehabilitation has narrowed the outcome gap with surgery considerably, and defining which patients still benefit from operating is an active question.
2
Scandinavian Journal of Medicine & Science in Sports · 2015
Eccentric rehabilitation exercise increases peritendinous type I collagen synthesis versus heavy slow resistance training
Comparative trial finding equivalent clinical outcomes between heavy slow resistance and eccentric protocols, with better patient satisfaction and adherence in the heavy slow resistance group.
Emerging therapies
- • Blood flow restriction training for early-stage Achilles rehabilitation when heavy loading is not tolerated
- • Nutritional timing protocols pairing collagen peptides with tendon loading
- • High-volume injection and needle tenotomy for chronic tendinopathy, with mixed evidence
- • Improved return-to-sport criteria based on measured tendon and calf capacity rather than time
Scientific controversies
- • Platelet-rich plasma injection is widely sold for Achilles tendinopathy despite consistently failing to beat placebo in trials — a clear case of commercial provision outpacing evidence.
- • Whether surgical or conservative management is preferable for acute Achilles rupture remains debated, with modern rehabilitation substantially reducing the difference.
- • The role of hydration and electrolytes in exercise-associated cramping is contested, with neuromuscular fatigue explanations now better supported than the traditional dehydration model.
Alfredson's 1998 eccentric heel-drop study is one of the most influential papers in sports medicine: recreational runners with chronic Achilles tendinosis, previously managed with rest, returned to pre-injury running after twelve weeks of deliberately painful loading. It overturned decades of rest-based practice and established the loading paradigm that now governs tendon rehabilitation throughout the body. The recognition that chronic tendon pain is degenerative rather than inflammatory — a shift in terminology from tendinitis to tendinopathy — followed from the same body of work and changed how the condition is treated.
Frequently asked questions
Should I stop running if my Achilles hurts?
Usually not entirely. Reducing volume while starting a progressive loading programme works better than complete rest, which deconditions the tendon further. Sharp pain, or morning stiffness worsening week on week, does warrant assessment.
How long does Achilles tendinopathy take to get better?
Twelve weeks is a realistic minimum, and many cases take longer. This is a property of collagen, which remodels slowly. The strongest predictor of success is whether the loading programme is continued for long enough — stopping early is the commonest reason people conclude it did not work.
How can I tell a calf strain from a blood clot?
A strain usually has a clear moment of onset during activity. A clot more often produces unilateral swelling, warmth and tenderness without a triggering event, particularly after immobility, surgery or long travel. If in doubt, get it assessed the same day.
Do I need surgery for a ruptured Achilles?
Not necessarily. Modern non-surgical management with early controlled loading in a boot produces comparable functional outcomes for many patients, though re-rupture rates are somewhat higher. The decision depends on your age, activity goals and the specific injury.
Why does my ankle keep giving way after a sprain?
Because most sprains are rehabilitated only until walking is painless, which leaves proprioceptive and strength deficits behind. Between a third and a half of people develop persistent instability. Balance training substantially reduces recurrence and is the step most often skipped.
Are cortisone injections good for Achilles pain?
Generally avoided. Corticosteroid around the Achilles is associated with tendon rupture, and while it may relieve pain briefly, long-term outcomes are worse. Progressive loading is the treatment with actual evidence behind it.
Does ankle stiffness matter if it does not hurt?
Yes. Ankle dorsiflexion range sets the mechanics for everything above it — restriction forces early heel rise in squatting and increases knee valgus on landing, shifting load to the knee, hip and low back.
Explore further
Keep exploring
Glossary
- Achilles tendon
- The combined tendon of gastrocnemius and soleus attaching to the heel; the strongest tendon in the body.
- Tendinopathy
- Degenerative tendon change with pain and reduced load tolerance; more accurate than 'tendinitis' for chronic cases.
- Dorsiflexion
- Bringing the toes toward the shin; restricted range here is a common driver of lower-limb problems.
- Plantarflexion
- Pointing the foot downward — the action the Achilles transmits.
- Eccentric loading
- Contracting while the muscle-tendon unit lengthens; the basis of the original Achilles rehabilitation protocols.
- Heavy slow resistance
- Slow, heavily loaded repetitions used in tendon rehabilitation, comparable in effect to eccentric protocols.
- Syndesmosis
- The fibrous connection between tibia and fibula above the ankle; high ankle sprains involve it and heal slowly.
- Chronic ankle instability
- Persistent giving way and reduced proprioception following inadequately rehabilitated ankle sprain.
- Elastic energy return
- The storage and release of energy in a stretched tendon, contributing substantially to running economy.
Trusted organisations & further reading
- NHS — Achilles tendinopathy
- NHS — Sprains and strains
- NHS — Deep vein thrombosis
- Versus Arthritis
- Rehab Science — Tom Walters. Clear progressive loading programmes for Achilles and ankle injuries with sensible progression criteria.
- Running Rewired — Jay Dicharry. Movement-focused approach to running mechanics with substantial lower-leg, ankle and foot content.
Medical disclaimer
This page is for general education and does not replace personalised medical advice. If you have concerning symptoms, or before starting a new supplement, medication or exercise programme, speak with a qualified healthcare professional.