Achilles Tendinopathy & Tendinitis

What Is Achilles Tendinopathy?

Achilles tendinopathy is a chronic degenerative disorder of the Achilles tendon, not acute inflammation. This distinction is crucial: while the term "tendinitis" suggests inflammatory cytokines and prostaglandins, actual histology reveals type III collagen proliferation, neovascularity, and failed tissue healing response. The terminology has shifted in modern sports medicine to "tendinopathy" to reflect the degenerative, not inflammatory, nature of the condition.

The Achilles is the strongest tendon in the human body, storing 35–52% of mechanical energy per stride during running. It routinely experiences forces of 6–12 times body weight. Yet it has a "watershed zone" 2–6 cm above the calcaneal insertion with relatively poor vascularity—this is why most chronic pathology occurs here. Pain, swelling, reduced function, and imaging findings (ultrasound/MRI) of tendon thickening and intratendinous signal changes define the condition. Symptoms typically worsen over weeks to months without intervention.

The Two Types: Midportion vs Insertional

Achilles tendinopathy is classified into two distinct phenotypes, each with different mechanical drivers and treatment responses:

This distinction guides treatment: midportion Achilles thrives on eccentric loading through plantarflexion (Alfredson), while insertional pathology requires load reduction at end-range and modified loading (avoid full dorsiflexion stretch). Understanding your phenotype is critical to treatment success.

Anatomy and Biomechanics

The Achilles tendon is the insertion of the gastrocnemius and soleus muscles onto the calcaneus (heel bone). It is approximately 15 cm long and 5–6 mm in cross-sectional area, making it the strongest tendon in the body. During running, the Achilles stores and releases elastic energy—up to 52% of the total metabolic cost of running is offset by this tendon stiffness, acting as a "spring."

The watershed zone (2–6 cm above insertion) has unique vascular anatomy: blood supply converges from proximal (muscular) and distal (calcaneal) sources, creating a relative hypovascular region. This zone experiences the highest mechanical stress and poorest nutrient diffusion, making it the site of 95% of chronic Achilles pathology. When training load exceeds the tendon's adaptive capacity—sudden increases in running volume, hill work, inadequate recovery—microtrauma accumulates, collagen fails to remodel properly, and degenerative pathology begins.

Who Gets Achilles Tendinopathy? Risk Factors

Achilles tendinopathy is multifactorial. The following risk factors significantly increase likelihood:

• Sudden training load increase: Most common trigger. A jump of >10% per week in running volume, intensity, or hill training overwhelms tendon capacity.
• Hill running and stairs: Eccentric lengthening at plantarflexion creates high tendon stress.
• Inadequate foot arch support: Overpronation (excessive inversion/eversion) increases shear forces on the tendon.
• Age: Peak incidence 35–45 years. Tendon collagen becomes less compliant and vascularization decreases with age.
• Sex: 2:1 male predominance (likely due to higher participation in high-impact sports).
• Obesity and diabetes: Systemic inflammation and poor glycemic control impair collagen synthesis and healing.
• Fluoroquinolone antibiotics: Ciprofloxacin, levofloxacin increase tendon rupture risk 10-fold. Avoid if possible in susceptible populations.
• Familial hypercholesterolaemia and hypothyroidism: Lipid and metabolic dysregulation impair tendon health.

Understanding your risk profile allows targeted prevention: gradual load progression (no >10% weekly increase), proper footwear, stretching, and addressing systemic factors (weight, metabolic health).

Evidence-Based Treatment: The Alfredson Protocol

The Alfredson protocol (1998) is the most studied, validated intervention for midportion Achilles tendinopathy. It is based on the principle of eccentric loading—lengthening the muscle-tendon unit under load—which triggers collagen remodeling, neovascularity, and tissue adaptation.

How to perform Alfredson:

• 3 sets of 15 repetitions, twice daily, 7 days per week
• Stand on a stair or step, heels hanging off the edge
• Rise onto toes using both legs; lower slowly using only the painful leg
• Full plantarflexion on rise; full dorsiflexion (stretch) on descent
• Duration: 12 weeks minimum
• Pain threshold: Up to 5/10 is acceptable; do not exceed 5/10 during exercise
• Continue through pain (not inflammation—tendinopathy is degenerative, not inflammatory)

Success in original study (Alfredson et al., 1998): 90% (14/15 patients) achieved pain relief and return to sport at 12 weeks. The Alfredson protocol has become the reference standard and is recommended by major guidelines (APTA, BJSM, ESPM).

Treatment Protocol at Recovery TLV: 3-Phase Rehabilitation

We follow evidence-based, load-management principles across three progressive phases:

Other Effective Modalities

Corticosteroid Injection: Kongsgaard et al. (Scand J Med Sci Sports 2010, n=60) showed corticosteroid injection inferior to heavy slow resistance and combined therapy at 6 months (p<0.01). Avoid corticosteroid injection for chronic Achilles tendinopathy; the short-term pain relief is offset by delayed healing and higher recurrence.

Heel Raise: Rowe et al. (J Foot Ankle Res 2012) documented that a 12–15mm heel raise reduces Achilles tendon load by ~20% during weight-bearing, providing pain relief early in rehabilitation. Taper gradually (weeks 4–12) to avoid prolonged plantarflexion shortening.

If conservative protocol fails (8–12 weeks): Consider physician referral to discuss additional medical options (e.g., imaging-guided procedures, sports-medicine consultation). Recovery TLV does not provide injection-based or device-based shockwave services in-clinic.

Five Common Questions About Achilles Tendinopathy

See Also: Related Conditions & Services