Achilles tendinopathy: what it is, and the loading that fixes capacity

You already know the pattern: the first few steps in the morning tell you exactly how yesterday went. That stiffness is the tendon reporting on load, and it is the most useful signal you have — which is why this program is built around it rather than around how the session felt at the time. Rest settles it and takes your push-off with it. Loading rebuilds it, but only at a rate this tendon will accept, and it is famously unforgiving about being rushed.

What it actually is

Achilles tendinopathy affects the thick tendon joining your calf muscles to your heel. The common form is mid-portion — a few centimetres above the heel bone — and it behaves quite differently from the insertional kind right at the bone, which does not tolerate the same stretching. The hallmark is morning stiffness that eases as you move, then returns after you stop.

Who gets it, and what it feels like

Runners most famously, but also racquet-sport players, who ask the calf for repeated hard push-offs and stops. Risk goes up with a sudden increase in volume, a change in footwear, and age. There is also a well-documented association with fluoroquinolone antibiotics, which is worth knowing because it changes how cautiously you should start.

What sets it off

The movements people most often report as the trigger, in roughly the order they come up:

• First steps in the morning
• Pushing off
• Running and sprinting
• Changing direction
• Stairs and hills
• Landing

When it is not this

Everything above assumes a tendon that is overloaded rather than something else wearing the same costume. These are the patterns that do not behave like a tendon problem, and any one of them is a reason to be assessed in person before loading anything:

• You cannot push off, go up on your toes, or there is a gap you can feel in the tendon. Those are the signs of a torn Achilles rather than an irritated one. A partial rupture can still let you walk, which is exactly why it gets missed. It needs imaging and an opinion this week, not a loading program.
• The pain is right on the back of the heel bone, not in the cord above it. Pain at the insertion is squeezed against the heel bone every time your ankle bends, so the standard heel-drop exercise makes it worse rather than better. It needs a different program — one that avoids that end range — which is worth getting set up properly.
• You have taken a course of antibiotics ending in "-floxacin" in the last six months. Ciprofloxacin and its relatives are associated with Achilles tendon damage and rupture, sometimes months after the course finished. Loading a tendon in that window is not something to start without a clinician knowing about it.
• Numbness, tingling, or pins and needles in the foot. Tendons do not cause numbness. Symptoms in the foot point at a nerve — either locally or referred from the back — and need a different assessment.
• The calf is swollen, hot, or tender in a way the tendon is not. A hot, swollen calf can be a blood clot, which is an emergency rather than an injury. It needs ruling out the same day.
• It started suddenly — a fall, a knock, or a pop you felt. A sudden mechanical onset suggests something tore or broke rather than gradually overloaded, and that has to be examined before it is loaded. This is the difference between a tendon that is irritable and a tendon that is no longer attached.
• Visible deformity, significant swelling, or heat around the joint. Swelling and heat are not typical of tendinopathy, and can indicate infection or an inflammatory joint problem.
• Unrelenting pain at night that wakes you and will not settle. Pain that does not ease with rest or position does not follow the tendon pattern and warrants a proper look.

Why resting it does not work

Rest reliably reduces pain, which is why it feels like the answer. The problem is what it does to capacity: a tendon that is not loaded gets weaker, and the muscle around it gets weaker faster. So the pain settles, you return to what you were doing, and the tendon now has even less tolerance than it had when it first complained. That is the cycle most people are in by the time they start looking things up.

What tendons respond to is load — applied heavily enough to be a stimulus, slowly enough to be controlled, and progressed only when the previous step has settled. That last part is the whole game, and it is where most self-directed attempts come apart.

What a proper progression looks like

Four phases. The order is not arbitrary: each one is only useful once the one before it has stopped being provocative.

The minimum time across those phases is around 8 weeks, and that is a floor rather than an estimate. Tendons need elapsed time as well as clean sessions, which is why a program that lets you skip ahead on enthusiasm is not doing you a favour.

The exercises

These are the movements the progression is built from. The cue matters more than the name — tempo is most of the stimulus in tendon work, and doing these fast turns them into something else entirely.

How much pain is acceptable

Up to about 5 out of 10 during loading is acceptable and expected. The number that actually decides whether a session was a good one is the next morning: if it has settled back to your normal baseline, that session was fine regardless of how it felt at the time. If it has not, that was too much — whatever the pain score said during it.

This is the rule most people get wrong in both directions. Some stop at any discomfort and never load enough to change anything; others push through a 9 and wonder why it is worse a fortnight later.

When to see someone

If any of the patterns in the section above apply, if it is getting worse rather than settling, or if it simply is not matching what is described here, see a physiotherapist or doctor. This page is general education about a common problem; it is not an assessment of yours, and it cannot be.