Etiology — what causes it

Load-related changes within the Achilles tendon mid-substance, driven by training error, abrupt volume increases, deconditioning, and insufficient eccentric capacity. Footwear, running surface changes, and lower limb biomechanics contribute.

Epidemiology — who gets it

Lifetime incidence in runners is around 50% (Lopes et al., Sports Med). Peak age 30–50 in recreational runners; younger in elite athletes.

Clinical signs

Tender thickening 2–6 cm proximal to the calcaneal insertion, painful arc with passive dorsiflexion, pain with heel raises, and positive Royal London Hospital test (pain at mid-tendon, less on stretch). VISA-A questionnaire tracks severity.

Symptoms

Pain and stiffness over the mid-Achilles, worse in the morning and at the start of activity, improving with warm-up but returning after. Progressive over weeks-to-months.

Best evidence for chiropractic treatment

JOSPT CPG (Martin et al., 2018), Alfredson protocol (eccentric loading), and Beyer et al. (AJSM 2015) heavy slow resistance protocol are foundational. Both eccentric and heavy slow resistance produce excellent outcomes; heavy slow resistance may be better tolerated and produces faster pain reduction. Shockwave is a supported adjunct in refractory cases.

When to seek emergency care

Some symptoms need urgent medical attention — not a chiropractic visit. Call 911 or go to the nearest emergency department for: progressive limb weakness, loss of bowel or bladder control, saddle anesthesia (numbness in the groin/inner thighs), severe unrelenting pain unrelieved by position, signs of fracture after significant trauma, chest pain, stroke-like symptoms (face drooping, arm weakness, speech changes), or any rapidly worsening or unusual symptom.

Bottom line

Mid-portion Achilles tendinopathy is a load capacity problem. Heavy slow resistance or eccentric protocols drive recovery over 12 weeks — no shortcuts.