Eccentric loading is the part of Achilles treatment that does the actual work. It is also the part most often done at the wrong dose, in the wrong range, or for the wrong length of time — and then written off as ineffective. This is what the programme looks like when it is done properly.
This article describes general practice for midportion Achilles tendinopathy. It is education, not a prescription, and it assumes a clinician has confirmed the diagnosis first. If you have not been assessed, start with Achilles Tendon Pain: Making the Exercise Possible.
What “eccentric” means
A muscle works concentrically when it shortens under load and eccentrically when it lengthens under load. For the calf, rising onto your toes is concentric; lowering your heel slowly back down — and below the level of your toes — is eccentric. Tendon appears to respond particularly well to that controlled lengthening phase, which is why the standard programme asks you to load only on the way down.
That detail is the one most often lost. If you rise and lower on the same affected leg, you are doing calf raises, not the programme.
The movement
Stand on the edge of a step, forefoot on the step, heels free to drop below it. Hold a rail.
- Rise onto your toes using both legs, or just the unaffected leg.
- Shift your weight onto the affected leg only.
- Lower that heel slowly — about three seconds — until it is below the level of the step.
- Return to the top using both legs again, and repeat.
Two versions are usually done: one with the knee straight and one with the knee slightly bent, which shifts the emphasis within the calf.
For insertional pain — pain right at the heel bone — the range changes. Do the same movement on flat ground and stop at neutral, without letting the heel drop below the toes. Taking an irritated insertion into full dorsiflexion compresses it against the bone and typically makes it worse. A temporary heel lift in your shoe helps during this phase.
The dose
The programme that the literature is built on is a substantial volume, and the volume is the point:
- 3 sets of 15 repetitions, knee straight
- 3 sets of 15 repetitions, knee slightly bent
- Twice a day
- Seven days a week
- For twelve weeks
That is 180 repetitions a day. It sounds like a lot because it is, and it takes about ten to fifteen minutes per session. People who treat it as “some calf exercises when I remember” generally do not get the result the trials report.
How to progress
When the exercise stops being uncomfortable, it has stopped being a stimulus. Progression is by load, not by repetitions: add weight in a backpack, or hold a dumbbell, in small increments, so that the final repetitions of each set remain mildly painful. Keep the sets and frequency the same and keep the tempo slow.
If you can do the full programme completely pain-free with no added load, you are ready to progress — or ready to stop.
Pain during the programme: what is expected and what is not
This is the question people most need answered, because the instinct to stop at the first twinge is what ends most attempts.
Expected: discomfort during the exercise itself, in the tendon, in the region you already hurt; some soreness afterwards that settles within 24 hours; morning stiffness that gradually shortens over the weeks.
Not expected, and worth a call: pain that is sharply worse the morning after and stays worse into the second day; swelling that is new or increasing; pain that moves from the tendon to the bone; any sudden sharp pain with difficulty pushing off, which needs urgent assessment rather than a modified programme.
The usual adjustment for the first category is to reduce the added load, not to stop the programme.
How we track it
We record a baseline before anything starts: pain on a 0–100 scale during the activity that matters to you, morning stiffness duration in minutes, single-leg heel-raise count, and ankle dorsiflexion range. Then we reassess at four weeks and at eight.
Four weeks is the honest first checkpoint. It is early enough to catch a programme being done in the wrong range or at too low a dose, and late enough to mean something. The twelve-week point is where the published outcomes are measured, so that is where we judge the programme as a whole.
Where an adjunct comes in
If the early weeks are painful enough to threaten adherence, that is the specific situation where we will discuss adding photobiomodulation. In the randomized trial underpinning this — 52 recreational athletes, eccentric exercise plus 820 nm laser versus eccentric exercise plus placebo laser — pain during activity was 33.0 mm versus 53.0 mm on a 100 mm scale at twelve weeks (P = .007), and the treated group reached at four weeks roughly what the placebo group reached at twelve.
Precisely stated: that is one trial, in recreational athletes, with one set of parameters, and both groups did the loading programme — the exercise is doing the work in each arm, and the light shortened the time to improvement rather than substituting for it. It is an adjunct to this programme, not an alternative, and photobiomodulation is not FDA-cleared for the treatment of Achilles tendinopathy.
The short version
Right range for your type of pain, enough volume, slow tempo, every day, twelve weeks, progress by adding load, and reassess on dates agreed in advance. That is most of it. Everything else is in service of getting you through those twelve weeks.
Reference
Stergioulas A, Stergioula M, Aarskog R, Lopes-Martins RAB, Bjordal JM. Effects of low-level laser therapy and eccentric exercises in the treatment of recreational athletes with chronic achilles tendinopathy. The American Journal of Sports Medicine. 2008;36(5):881–887. PMID 18272794. doi:10.1177/0363546507312165 Citation retrieved from PubMed.
This article is general education, not medical advice, and it is not a substitute for evaluation by a qualified clinician. It does not establish a physician–patient relationship. Individual results vary, and the studies described report group averages rather than what any one person should expect. Treatments discussed may not be FDA-cleared or approved for the conditions mentioned; where that is the case it is stated in the text. Talk to your own physician before starting, stopping or changing any treatment.
