Why Your Achilles Hurts From Running and How to Fix It

Achilles tendinopathy is the most common Achilles tendon injury in runners. It causes pain, stiffness, and sometimes swelling in the tendon connecting the calf muscles to the heel bone. Among elite track and field athletes, 43% report current or prior Achilles tendinopathy symptoms. Training-load errors account for 60-80% of cases: sudden increases in running volume, intensity, or hill work that exceed the tendon's ability to adapt. The treatment with the strongest evidence is exercise that provides mechanical loading to the tendon (Strength of Recommendation: A). This means progressive loading through eccentric and concentric exercises, not complete rest. Recovery follows a four-phase protocol over 3-6+ months. Reinjury rates are 27-44% when athletes rush back too quickly. The best prevention: recognise early minor symptoms (morning stiffness, mild post-run tenderness) and reduce load immediately rather than running through them.

Understanding Achilles Tendinopathy

Tendinopathy vs tendinitis: The older term tendinitis implies acute inflammation. Current research uses tendinopathy because most chronic Achilles tendon pain involves degenerative changes in the tendon structure (failed healing response), not active inflammation. This distinction matters because anti-inflammatory treatments alone do not address the underlying problem.

Midportion vs insertional: Midportion tendinopathy (pain 2-6 cm above the heel) is more common in runners and responds better to eccentric exercises. Insertional tendinopathy (pain at the heel bone attachment) often involves the bursa and may need different management. The location of your pain determines the best treatment approach.

Why runners are vulnerable: During running, the Achilles tendon absorbs forces of 6-8x body weight. The calf muscles must alternate rapidly between eccentric (absorbing landing forces) and concentric (pushing off) contractions. When training load exceeds the tendon's capacity to remodel, the tendon structure degrades. The tendon has lower blood supply than muscle, so it heals more slowly and is less tolerant of sudden load increases.

Identifying the biomechanical factors that increase your tendon loading is important for prevention. An Arion Running Analysis measures ground contact time, push-off force distribution, and left-right asymmetry, which helps pinpoint whether one side is absorbing disproportionate load.

Treatment: The Four-Phase Protocol

Phase 1: Symptom Management (Weeks 1-2+)

  • Reduce running volume to a level where pain stays below 3/10 during and after running. Complete rest is not recommended unless pain prevents walking.
  • Isometric calf holds: stand on one leg, rise onto toes, hold for 45 seconds. 4 sets, 3 times daily. Isometrics reduce pain acutely and maintain tendon load.
  • Avoid stretching the Achilles aggressively. Passive stretching into dorsiflexion can compress the tendon and worsen symptoms. Gentle calf stretching only.
  • Ice after activity for 10-15 minutes if pain is acute. NSAIDs may provide short-term pain relief but do not improve tendon healing long-term.

Phase 2: Recovery (Weeks 2-5+)

  • Eccentric heel drops (Alfredson protocol): Stand on a step on the ball of your foot. Rise on both feet, then lower slowly on the injured side only over 3-5 seconds until the heel drops below the step. 3 x 15 reps, twice daily (morning and evening). This is the exercise protocol with the most research support for midportion Achilles tendinopathy.
  • A systematic review and meta-analysis found eccentric exercise more effective than other exercise types for midportion Achilles tendinopathy.
  • Expect some discomfort during the exercises (up to 4-5/10 pain is acceptable). Pain should not increase the next day. If it does, reduce the load or range of motion.
  • Continue isometric holds from Phase 1 as a warm-up before eccentric work.

Phase 3: Rebuilding (Weeks 3-12+)

  • Progress to weighted eccentric heel drops: hold dumbbells or wear a loaded backpack to increase tendon load progressively.
  • Add concentric-eccentric calf raises: 3 x 12, progressing load over weeks. Research shows combined concentric-eccentric loading produces comparable results to pure eccentric work.
  • Introduce plyometric loading: small bilateral hops, progressing to single-leg hops. Start with 2 x 10, progress slowly.
  • Gradually increase running volume. Start with walk-run intervals if you reduced to zero. Increase by no more than 10% weekly.

Phase 4: Return to Sport (3-6+ Months)

  • Full return to running when you can do 20 single-leg calf raises to full range without pain, and your running volume is back to pre-injury levels without morning stiffness.
  • Continue eccentric exercises as maintenance: 3 x 15, 3 times per week, indefinitely. This reduces reinjury risk, which is 27-44% without maintenance.
  • Monitor load carefully. The tendon is remodelled but not fully mature for 12+ months after symptoms resolve.

Prevention

  • The single most effective prevention: catch early warning signs. Morning stiffness in the Achilles that resolves after a few minutes of walking is the earliest indicator. Reduce training load by 20-30% immediately when this appears.
  • Avoid sudden increases in running volume, intensity, or hill work. Follow the 10% weekly increase rule.
  • Maintain calf strength year-round with regular calf raises (3 x 15, twice per week). A strong calf absorbs more of the running forces that would otherwise load the tendon.
  • If you notice asymmetrical push-off patterns or one calf fatiguing faster than the other, a structured insole like the Shapes HYROX Edition can help maintain even force distribution during running. Pair it with an Arion Running Analysis to quantify any left-right loading imbalance that may be overloading one Achilles tendon.

FAQ

What causes Achilles tendon pain from running?

Training-load errors account for 60-80% of cases: sudden increases in volume, intensity, or hill running that exceed the tendon's ability to adapt and remodel. Other risk factors include weak calf muscles, decreased ankle dorsiflexion, increased foot pronation, and low running experience. The Achilles tendon absorbs 6-8x body weight during running, and its low blood supply means it heals slowly.

Can I run with Achilles tendon pain?

Often yes, at reduced volume. If pain stays below 3/10 during running and does not worsen in the 24 hours after, you can continue with modified load. Reduce volume by 30-50%, avoid hills and speed work, and combine with the eccentric exercise protocol. If pain exceeds 5/10 during running or is present when walking, stop running and focus on the rehabilitation phases before returning.

How long does Achilles tendinopathy take to heal?

Full recovery takes 3-6+ months with consistent rehabilitation. The four-phase protocol progresses from symptom management (weeks 1-2) through recovery, rebuilding, and return to sport. The tendon continues remodelling for 12+ months after symptoms resolve. Reinjury rates are 27-44% when athletes rush back. Patience and continued maintenance exercises are critical.

What are the best exercises for Achilles tendinopathy?

Eccentric heel drops (Alfredson protocol) have the most research support for midportion tendinopathy: 3 x 15 reps, twice daily, lowering slowly over 3-5 seconds. A systematic review found eccentric exercise more effective than other exercise types. Additionally, isometric calf holds (45-second holds, 4 sets) reduce pain acutely. Combine both, progressing to weighted and plyometric loading over months.

Do eccentric heel drops really work for Achilles pain?

Yes, with strong evidence for midportion tendinopathy. A meta-analysis confirmed eccentric exercise is more effective than other exercise forms for this condition. The mechanism involves progressive tendon remodelling under controlled load. Some discomfort during the exercise (up to 4-5/10) is acceptable. Results typically appear after 4-6 weeks of consistent daily performance. They work less well for insertional tendinopathy, where the protocol needs modification.

How do I prevent Achilles tendon injuries when running?

Three key strategies: catch early warning signs (morning Achilles stiffness that resolves with walking means you need to reduce load by 20-30% immediately), avoid sudden training load increases (follow the 10% weekly rule), and maintain calf strength year-round (3 x 15 calf raises, twice weekly). The tendon adapts to load slowly, so gradual, consistent progression is the best protection.

Sources

  1. Current Clinical Concepts: Conservative Management of Achilles Tendinopathy - PMC
  2. Eccentric Exercise for Achilles Tendinopathy: A Narrative Review and Clinical Decision-Making Considerations - PMC
  3. Eccentric Exercise is More Effective Than Other Exercises for Mid-portion Achilles Tendinopathy: Systematic Review and Meta-Analysis - BMC Sports Science