Achilles tendinopathy: why not 'tendinitis', and why is exercise the first-line treatment?

Short answer

Most people call chronic tendon pain behind the heel "Achilles tendinitis"; yet the suffix "-itis" denotes inflammation, and in chronic cases the dominant picture is not classic inflammation. What changes is the arrangement of the collagen fibers and the tendon's load-bearing capacity. That is why current medicine uses the term "Achilles tendinopathy" — and this name also changes the treatment: if you see the problem as inflammation you focus only on silencing it, but if you see it as tendinopathy you focus on preparing the tendon to carry load again.

The strongest evidence is for progressive tendon-loading exercises performed under supervision (usually at least 12 weeks). As an adjunct to exercise, extracorporeal shock wave therapy (ESWT) — especially in insertional cases (at the heel attachment) and in cases resistant to exercise — is an evidence-based, effective option. By contrast, in randomized trials PRP injection has not shown significant superiority over placebo.

Why does the name matter?

In chronic Achilles pain, what is seen under the microscope is not classic inflammatory cells but disorganized collagen and altered tendon structure. For this reason the logic of treatment is not "to extinguish inflammation" but to rebuild the tendon's capacity through gradual loading. The location of the pain also matters: whether it is in the mid-portion of the tendon or at the heel attachment (insertional) affects the choice of exercises and the suitability of certain movements (e.g. dropping the heel off a step).

The center of treatment: gradual loading

Programs are built on progressive strengthening of the calf muscles and the tendon (eccentric-weighted programs or heavy-slow resistance work; both are effective).
Meaningful improvement usually takes 12 weeks or more; patience and consistency are as important as the technique itself.
Mild-to-moderate pain during exercise that settles quickly is considered acceptable in most programs; pain that increases and carries into the next day requires the dose to be readjusted.
Load management is the other half of the job: sudden increases in training volume that trigger pain are reversed; running is often not stopped completely, but its dose is regulated.

PRP and other injections: what does the evidence say?

Platelet-rich plasma (PRP) is one of the most-asked-about options. However, placebo (saline)-controlled randomized trials and current analyses combining them show that in Achilles tendinopathy PRP provides no significant added benefit in pain and function. A procedure that looks impressive is not always an effective treatment. Corticosteroid (cortisone) injection into the tendon is not recommended; it has been associated with a risk of weakening the tendon and rupture.

Shock wave therapy (ESWT): a strong adjunct to exercise

Extracorporeal shock wave therapy (ESWT) is a needle-free and surgery-free method that stimulates a healing response with pressure waves applied externally to the tendon region. Unlike PRP, the evidence supporting ESWT in Achilles tendinopathy is markedly stronger:

Meta-analyses combining randomized trials show that ESWT significantly improves pain and function in chronic Achilles tendinopathy compared with sham (placebo) application and some conventional treatments.
The most consistent benefit appears when ESWT is used alongside, not instead of, exercise. In one quality study, in the group where ESWT was added to loading exercise, about 80% of patients reported marked improvement or full recovery, and this group was found superior to those who did exercise alone.
It stands out especially in two situations: (1) tendinopathy at the heel attachment (insertional) — where exercise alone works less well; (2) resistant cases that do not improve despite an adequately long exercise program.

In short, ESWT is an evidence-based and strong option that complements gradual loading, the foundation of treatment. It has two main forms (focused and radial); the number of sessions and the energy level are adjusted to the individual. It is generally well tolerated; there may be short-term pain and skin redness during or after the application.

Not only an athlete's disease

Runners come to mind when Achilles tendinopathy is mentioned; yet in population data about two-thirds of cases occur in people who do not do sport. This is because tendon load does not come only from training: standing for long periods, body weight, age, diabetes, cholesterol disorders, and some medications (for example quinolone-derivative antibiotics — such as ciprofloxacin, levofloxacin) can affect tendon health. So merely stopping running may not solve the whole problem; along with the loading pattern, metabolic risks and the medications used should also be assessed.

⚠ Seek urgent assessment: If there is a sudden "pop/snap" sensation in the Achilles, a sharp pain as if kicked from behind, marked loss of power, or an inability to rise onto the toes of one foot, this may not be tendinopathy but an Achilles tendon rupture; see a physician without delay.

For clinicians

The distinction between mid-portion and insertional tendinopathy changes program design (in insertional cases, loading in deep dorsiflexion is initially limited). The differential should consider retrocalcaneal bursitis, Haglund deformity, plantaris involvement, and partial rupture. A history of quinolone-derivative antibiotic use (such as ciprofloxacin, levofloxacin) and the metabolic profile (DM, dyslipidemia) should be questioned; in resistant cases, imaging and stepwise add-on treatments should be considered. At this point ESWT is a strong add-on treatment: meta-analyses report a favorable effect on pain and function (standardized mean difference for pain ~-1.4 in chronic cases), with the most consistent result obtained when combined with loading exercise; it should be considered first-line in insertional tendinopathy and in exercise-resistant mid-portion cases. The quality of evidence is moderate, and there is heterogeneity among protocols (focused/radial, energy, sessions).

Frequently asked questions

What is the difference between tendinitis and tendinopathy?

"Tendinitis" implies an acute inflammatory picture; in chronic tendon pain, however, the dominant finding is not inflammation but disruption of collagen order and loss of capacity. That is why the current literature prefers the term "tendinopathy." The difference is not academic but practical: the goal of treatment is not to silence inflammation but to make the tendon carry load again.

Can I keep running?

In most cases running is not completely forbidden; volume and pace are rearranged according to the pain response. The general principle: mild pain during activity that settles quickly is acceptable; pain that steadily increases or carries into the next day indicates the dose is too high. An assessment is needed for a personal plan.

PRP was recommended to me; should I have it?

In Achilles tendinopathy, placebo-controlled trials show that PRP provides no significant added benefit. The evidence-based first step is a structured loading program of at least 12 weeks. If PRP is being considered, its evidence status and cost should be discussed openly with your physician.

Will a cortisone injection be the solution?

Corticosteroid injection into the tendon is not recommended; even if it provides short-term relief, it can weaken the tendon tissue and has been associated with a risk of rupture.

Does shock wave therapy (ESWT) work? How does it differ from PRP?

Yes — the evidence supporting ESWT is markedly stronger than that for PRP. Meta-analyses show that ESWT significantly improves pain and function in chronic Achilles tendinopathy; the best result comes when you apply ESWT together with loading exercise. It is a valuable option especially in pain at the heel attachment (insertional) and in resistant cases that do not improve despite exercise. It is needle-free and surgery-free; it does not replace exercise but strengthens it.

Is it normal to have pain while exercising?

In tendon-loading programs, mild-to-moderate pain that settles quickly after exercise is considered acceptable in most protocols. Pain that worsens, wakes you at night, or carries into the next day indicates that the program dose needs adjusting.

I don't do sport but I have Achilles pain; why?

About two-thirds of cases occur in people who do not do sport. Standing for long periods, weight, age, diabetes, cholesterol disorders, and some quinolone-derivative antibiotics (such as ciprofloxacin, levofloxacin) affect tendon health. For this reason the assessment looks not only at activity but at the overall health picture.

Does surgery ever come up?

Rarely — in selected cases that do not respond to long-term (usually 6 months+) properly applied conservative treatment, surgery may be considered as an option. The first step is always a structured loading program.

Scientific references

Author's own work:
Benli M, Tatari H, Balcı A, Peker A, Şimşek K, Yüksel O ve ark. A comparison between the efficacy of eccentric exercise and extracorporeal shock wave therapy on tendon thickness, vascularity, and elasticity in Achilles tendinopathy: a randomized controlled trial. Turk J Phys Med Rehabil 2022;68(3):372-80.
Other references:
Kearney RS ve ark. Effect of platelet-rich plasma injection vs sham injection on tendon dysfunction in patients with chronic midportion Achilles tendinopathy: the ATM randomized clinical trial. JAMA 2021;326:137-44.
Alfredson H ve ark. Heavy-load eccentric calf muscle training for the treatment of chronic Achilles tendinosis. Am J Sports Med 1998;26:360-6.
Beyer R ve ark. Heavy slow resistance versus eccentric training as treatment for Achilles tendinopathy: a randomized controlled trial. Am J Sports Med 2015;43:1704-11.
de Jonge S ve ark. Incidence of midportion Achilles tendinopathy in the general population. Br J Sports Med 2011;45:1026-8.
Scott A ve ark. ICON 2019: International Scientific Tendinopathy Symposium consensus on clinical terminology. Br J Sports Med 2020;54:260-2.
Rompe JD ve ark. Eccentric loading versus eccentric loading plus shock-wave treatment for midportion Achilles tendinopathy: a randomized controlled trial. Am J Sports Med 2009;37:463-70.
Rompe JD ve ark. Eccentric loading compared with shock wave treatment for chronic insertional Achilles tendinopathy: a randomized, controlled trial. J Bone Joint Surg Am 2008;90:52-61.
Mani-Babu S ve ark. The effectiveness of extracorporeal shock wave therapy in lower limb tendinopathy: a systematic review. Am J Sports Med 2015;43:752-61.
Note: current evidence on the routine benefit of ESWT is debated; current sham-controlled trials and meta-analyses call for individual assessment (see current JOSPT reviews on Achilles tendinopathy).
Author's own content: Achilles tendinitis or tendinopathy?

This information is for general guidance only; it does not replace an examination, a diagnosis, or your physician's individual advice. Please consult a physician for your symptoms. About the author: Doç. Dr. Oğuz Yüksel — Academic Profile.