What is Achilles Tendonitis?

A clear, jargon-free explanation of what's happening in your body

The Achilles tendon connects your calf muscles to your heel bone and handles forces of up to 8x your body weight during running. Achilles tendonitis is inflammation of this tendon — most commonly caused by a sudden increase in training load, tight calf muscles, or poor footwear. It causes pain and stiffness at the back of the heel, especially in the morning and after exercise. Left untreated, it can progress to tendon degeneration (tendinosis) or complete rupture.

What Causes Achilles Tendonitis?

Understanding the root cause is the first step toward effective treatment

Training Load Spike

The most common cause. Adding too much mileage, speed, or hills too quickly overwhelms the tendon's ability to adapt. The "10% rule" exists for a reason.

Tight Calf Muscles

Limited ankle flexibility puts excessive strain on the Achilles with every step. Calf tightness is almost universal in Achilles tendonitis patients.

Poor Footwear

Transitioning to minimalist shoes too quickly, worn-out running shoes, or shoes with insufficient heel drop all increase Achilles load.

Biomechanical Issues

Overpronation, leg length discrepancy, and weak hip muscles all alter how force is distributed through the Achilles during running and walking.

Treatment Options

Ranked by effectiveness — most patients start conservative and escalate only if needed

Eccentric Heel Drop Protocol

✓ Usually covered ⏱ 12 weeks

Effectiveness

90%

The gold standard treatment. Slow, controlled lowering of the heel strengthens the tendon under load. Alfredson protocol: 3 sets of 15 reps, twice daily for 12 weeks.

Physical Therapy

✓ Usually covered ⏱ 8-12 weeks

Effectiveness

85%

Supervised rehabilitation including eccentric loading, manual therapy, and sport-specific return-to-activity programming.

Custom Orthotics with Heel Lift

✓ Usually covered ⏱ 4-8 weeks

Effectiveness

75%

Reduces Achilles load and corrects biomechanical contributors. Heel lift takes tension off the tendon during the acute phase.

Shockwave Therapy

Out of pocket ⏱ 3-6 weeks

Effectiveness

78%

Most effective for insertional Achilles tendonitis (where the tendon attaches to the heel bone) that hasn't responded to PT.

PRP Injections

Out of pocket ⏱ 6-12 weeks

Effectiveness

76%

Platelet-rich plasma promotes tendon healing in chronic cases. Emerging evidence supports use after failed conservative treatment.

Activity Modification

✓ Usually covered ⏱ 2-6 weeks

Effectiveness

65%

Strategic load reduction while maintaining fitness. Cross-training with swimming or cycling keeps athletes fit without aggravating the tendon.

Products That Actually Help

Podiatrist-vetted picks — not every product works, these ones do

Best Brace

AchilloTrain Ankle Brace

$65

The most-researched Achilles support brace. Applies targeted compression and includes a massage pad over the tendon. Reduces pain and supports return to activity.

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Best Running Shoe

Hoka Clifton 9

$145

High heel-to-toe drop (5mm) reduces Achilles load during running. The go-to recommendation for Achilles patients returning to running. Max cushioning without sacrificing responsiveness.

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Essential for Recovery

Slant Board for Eccentric Exercises

$45

Essential for the Alfredson eccentric heel drop protocol — the single most evidence-based treatment for Achilles tendonitis. Adjustable angle for progressive loading.

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Best Recovery Tool

Trigger Point Foam Roller

$35

Daily calf rolling reduces the muscle tightness that stresses the Achilles. 5 minutes before and after runs significantly reduces tendon load.

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Note: BestPodiatrists.com may earn a commission from purchases through these links at no extra cost to you. We only recommend products podiatrists actually use and recommend.

Frequently Asked Questions

Real questions from patients — answered without the medical jargon

Can I keep running with Achilles tendonitis? ▼

Often yes, with modifications. Reduce mileage by 50%, eliminate hills and speed work, and avoid back-to-back running days. If pain exceeds 4/10 during a run or gets worse as you run (rather than warming up), take a full week off. Running through mild Achilles tendonitis with proper management is generally safe — running through severe pain risks converting acute tendonitis into chronic tendinosis, which is significantly harder to treat.

What's the difference between Achilles tendonitis and a rupture? ▼

Tendonitis is inflammation — gradual onset, aching pain, morning stiffness. A rupture is sudden and dramatic — a sharp pop or snap, immediate severe pain, inability to push off the foot, and visible gap or bruising above the heel. If you experience these symptoms, go to an emergency room immediately. Ruptures require surgical repair within days for optimal outcomes.

What is the Alfredson protocol? ▼

The evidence-based eccentric loading program developed by Dr. Håkan Alfredson in 1998. Standing on the edge of a step, you raise up on both feet, then lower down slowly on only the affected foot — both with knee straight and knee bent. 3 sets of 15 reps, twice daily, for 12 weeks. It's deliberately painful (Alfredson designed it that way) and has a 90% success rate in research. Your podiatrist or PT will guide proper execution.

How long does Achilles tendonitis take to heal? ▼

Acute tendonitis: 6–12 weeks with proper treatment. Chronic tendinosis (where the tendon has degenerated): 3–6 months. The critical factor is consistency with the eccentric loading protocol — patients who do the exercises twice daily heal significantly faster than those who do them intermittently. Returning to sport too early is the most common reason for re-injury.