Achilles Tendinitis: Causes, Eccentric Rehab & Prevention

Quick Answer: Achilles tendinitis is an overuse injury of the tendon connecting your calf muscles to your heel bone, usually from a sudden jump in running or jumping, tight calves, flat feet or worn-out shoes. The gold-standard treatment is not rest alone — it is progressive eccentric heel-drop exercises, done twice daily for about 12 weeks, alongside load management, ice and supportive footwear. Expect 2–3 months, not days, for real improvement.

Your Achilles tendon is the strongest tendon in your body — and one of the most overloaded. Every run, jump and hill rep loads it with several times your body weight. When load rises faster than the tendon can adapt, its fibres become irritated and degenerate. That is Achilles tendinopathy (often called tendinitis): pain and stiffness at the back of the heel, worst in the morning and at the start of activity.

When to see a doctor

See a clinician promptly if you hear or feel a pop in the back of the ankle (possible rupture — this needs urgent care), if you cannot walk or push off, if there is sudden swelling or bruising, or if pain does not improve after 2 weeks of sensible home care. Anyone with diabetes, poor circulation or numb feet should get Achilles pain checked promptly. Imaging (ultrasound or MRI) is used when a tear is suspected or cases are chronic.

What causes it

Sudden load jumps: more mileage, hills, sprints or jumping, too fast.
Tight calves and poor ankle mobility: stiff calves force the tendon to work harder.
Foot mechanics: flat feet and overpronation twist and overload the tendon.
Weakness: weak calves, glutes and hamstrings leave the tendon carrying too much.
Footwear and surfaces: worn-out shoes, unsupportive shoes and hard or uneven surfaces.
Age and arthritis: tendons lose elasticity with age; a heel bone spur can irritate the tendon where it attaches.

Symptoms

Pain and stiffness along the back of the heel, worst in the morning and easing as you move
Tenderness when you press the tendon, and pain with calf raises
Swelling or a thickened, lumpy tendon over time
Reduced ankle flexibility and weaker push-off
Sometimes a creaking feeling when the tendon moves

What actually helps

Eccentric heel drops (the key treatment): standing on a step, rise on both feet, then lower slowly on the sore leg so the heel drops below step level. The landmark Alfredson protocol uses 3 sets of 15, twice daily, for 12 weeks. Expect mild discomfort during the exercise — sharp pain means stop and get advice.

Eccentric heel drops on a step are the key Achilles rehab exercise.

Load management: cut the aggravating activity, switch to low-impact options (cycling, swimming) and return gradually. Do not run through Achilles pain.
Ice: 15–20 minutes, 2–3 times a day, stopping if the area goes numb.
Calf stretching and strengthening: gentle calf stretches plus progressive calf strengthening rebuild tendon capacity.
Footwear and heel lifts: supportive shoes and a small heel lift reduce tendon strain; a brace or boot may be used short-term for severe cases.

A small heel lift in a supportive shoe reduces strain on the tendon.

Further care: physical therapy, shockwave therapy for chronic cases, and surgery only when conservative care fails over months.

Daily routine for Achilles rehab

Morning: gentle calf stretch before first steps; eccentric heel drops (3 × 15).
Through the day: supportive shoes with a heel lift; avoid barefoot walking and hills.
After activity: ice 15 minutes.
Evening: second round of eccentric heel drops plus calf stretching.
Weekly: add load only if pain during exercise stays mild and settles within 24 hours.

Frequently asked questions

How long does Achilles tendinitis take to heal?

At least 2–3 months for most cases, and 8–12+ weeks of eccentric rehab for chronic ones. Tendons remodel slowly — patience is part of the treatment.

Should I rest completely?

No. Complete rest weakens the tendon further. Reduce load, stay mobile with low-impact activity, and load the tendon progressively with eccentric exercise.

Do eccentric heel drops really work?

They are the best-supported conservative treatment: Alfredson et al. (1998) showed twice-daily eccentric drops for 12 weeks significantly reduced pain and restored function in chronic mid-portion tendinopathy.

Can I run with Achilles tendinitis?

Not through pain. Return only when you can do pain-free toe raises, then progress through walking, jumping rope and easy running over weeks.

What is the difference between tendinitis and tendinosis?

Tendinitis implies acute inflammation; most chronic cases are actually tendinosis — tendon degeneration without much inflammation. That is why anti-inflammatories alone rarely fix it, and loading exercises matter more.

Sources

Footcarely is reader-supported. We don’t use affiliate links yet — when we do, this page will say so. This guide is general information, not medical advice. Persistent foot pain deserves a podiatrist, not just new shoes.