What to Do When Achilles Tendinitis Becomes Chronic? Key Timing for Eccentric Training and Shockwave Therapy

Introduction

The Achilles tendon is one of the strongest yet most problem-prone tendons in the human body. It connects the triceps surae muscle group to the calcaneus and is the core driver of push-off in running. When runners complain of “stiff Achilles tendon, tightness on the first step in the morning, and pain going up and down stairs the day after a run,” they have often already entered the realm of Achilles tendinopathy. Notably, if symptoms persist for more than 3 months without improvement, the condition is considered chronic, and the treatment strategy must be fundamentally changed.

Two Types, Very Different Treatments

• Mid-portion tendinopathy: Located 2–6 cm above the calcaneus, the most common type, accounting for 55–65% of cases.
• Insertional tendinopathy: Located at the posterosuperior aspect of the calcaneus, often associated with Haglund’s deformity, and more challenging to treat.

Distinguishing between the two types is crucial because full eccentric lowering exercises are contraindicated for insertional tendinopathy (they compress the insertion site); a flat-surface version should be used instead.

3 Warning Signs of Chronicity

• Pain persisting for more than 12 weeks
• Imaging (ultrasound or MRI) showing tendon thickening, hypoechoic areas, or neovascularization
• Morning stiffness lasting more than 15 minutes, with significant worsening the day after a run

Treatment Stage Comparison Table

The Golden Alfredson Eccentric Training Protocol

This is the classic protocol proposed by Hakan Alfredson in 1998, and it remains at Level 1 evidence to this day:

• Stand on the edge of a step, with the forefoot firmly planted and the heel hanging off.
• Use the healthy leg to assist in rising to the highest point.
• Lower slowly using only the affected leg over 3 seconds, until the heel drops below the step surface.
• Straight knee: 15 reps × 3 sets + bent knee: 15 reps × 3 sets.
• Perform twice daily for 12 weeks.
• Pain during training is acceptable (VAS no higher than 5/10)—this is a counterintuitive but important principle.

The Role of Shockwave Therapy

Extracorporeal shockwave therapy (ESWT) has Level 1 evidence for chronic Achilles tendinopathy. Recommended timing:

• No progress after 6 weeks of eccentric training
• Imaging shows significant structural abnormalities
• Typically 3–5 sessions, once per week, with 5–7 days between sessions
• Eccentric training can continue after treatment; no need to pause

Injection Treatment Options

• PRP (platelet-rich plasma): Suitable for chronic degeneration or cases unresponsive to shockwave; requires a 2–3 week break from running.
• High-concentration dextrose prolotherapy: Lower cost, with efficacy similar to PRP; requires 3–5 sessions.
• Avoid corticosteroids: They increase the risk of tendon rupture by up to 9-fold; consider only in cases of tenosynovitis.

Practical Recommendations

• Keep weekly mileage increases to 5%/week—more conservative than the typical 10%—to give the tendon time to adapt.
• Strengthen the glutes and anterior lower-leg muscles to share the load on the Achilles tendon.
• Choose shoes with a 4–8mm heel-to-toe drop; excessively low drops (such as minimalist shoes) significantly increase Achilles tendon load.
• Perform calf stretches after running: gastrocnemius (straight knee) and soleus (bent knee), 30 seconds × 3 sets each.
• Supplementing with collagen (with vitamin C) 30–60 minutes before training may benefit tendon synthesis.

Conclusion

Chronic Achilles tendinopathy is not a death sentence—it is the body telling you that your training approach needs adjustment. With patience through 12 weeks of eccentric training, adding shockwave therapy when necessary, most runners can return to the race course. Remember this: “What the tendon needs is not rest, but the right load.”

Related Reading

• The Golden Treatment Protocol for Achilles Tendinitis: The Scientific Basis and Complete Execution Guide for Eccentric Training
• Conservative Treatment and Return-to-Training Criteria for Achilles Tendinitis
• Achilles Tendinopathy: The Eccentric Solution for Morning Stiffness and Start-of-Run Tightness
• Achilles Tendon (Tendo Achillis) Tendinopathy: Why Eccentric Training Is the Gold Standard for Rehabilitation