The short answer
- Stopping completely is rarely necessary. In a randomised trial, people who kept running within set pain limits did as well as people who stopped for six weeks.
- Pain up to 5 out of 10 during and after a run is acceptable if it has settled by the next morning and isn't rising from week to week.
- Cut hills and fast running first. Keep the easy running that passes the next-morning check.
- Heavy, slow calf work builds the capacity. On average the improvement is clear by 12 weeks, and full recovery often takes 6 to 12 months.
- A sudden pop at the back of the ankle, or suddenly being unable to push off, needs a medical check the same day.
It starts as stiffness on the first steps out of bed. It eases once you're moving, so you run. A few weeks later the hill at kilometre three hurts, and the morning stiffness lasts until the coffee is made.
That is the typical story of Achilles tendinopathy in a runner. The usual first advice is to stop running, and for most people that advice costs fitness without speeding anything up.
What's going on in the tendon
Every stride stretches the Achilles and lets it recoil, and during running it carries roughly five to seven times your body weight per step. Tendon adapts to that load more slowly than muscle does. When the demand jumps faster than the tendon can follow, it becomes painful. The jump is usually easy to find in hindsight: more kilometres per week, new hill repeats or a return to track sessions1.
Pain here tells you the tendon is irritated by what you're currently asking of it. It is a poor guide to how much damage there is. That is also why a scan rarely helps. Across 91 imaging studies of people with no Achilles pain at all, the share with abnormal-looking tendons ranged from 0 to 80%, and it was higher in people over 40 and in those who exercise regularly2. The diagnosis comes from your history and from how the tendon responds to heel raises and hops1.
Where the pain sits matters more than what a scan shows, because it changes how the rehab starts.
- Where
- MidportionYou can pinch the sore part between two fingers, 2 to 6 cm above the heel bone.
- InsertionalYou point at the back of the heel bone itself.
- Worst test
- MidportionHopping usually hurts more than a deep heel drop off a step.
- InsertionalA deep heel drop off a step usually hurts more than hopping.
- Calf raises
- MidportionWork towards full range off a step.
- InsertionalStart on flat ground and add range gradually.
The insertional kind is sensitive to compression. When the ankle bends far upward, the tendon is pressed against the heel bone, which is why calf stretches and heel drops can make it worse1.
Do you need to stop running?
Rarely, and there is a trial that tested it directly.
The trial was small, so it can't rule out rare problems. It does undercut the main argument for forced rest, which is that running slows recovery. Clinical guidelines now recommend staying active within acceptable pain rather than stopping1.
Many runners are quietly afraid the tendon will snap. Ruptures do happen: in a large US insurance database, 4% of people diagnosed with Achilles tendinopathy later had one, and older patients were the most vulnerable5. A rupture announces itself suddenly, and the signs are listed at the end of this article. A familiar ache that settles overnight is a different situation.
How much pain is acceptable?
The pain-monitoring model gives you three checkpoints4. Runners tend to watch the first and ignore the one that matters most.
- During the run, pain can reach 5 out of 10.
- After the run, it can also reach 5, but it should have settled by the next morning.
- From week to week, pain and morning stiffness should not be rising.
The next-morning check
| Run | Before the run | During the run | That evening | Next morning |
|---|---|---|---|---|
| Dose that fits | 1 | 3 | 3 | 1 |
| Dose too high | 1 | 5 | 6 | 4 |
Five out of 10 sounds high if you were told that any pain means stop. It is in line with the wider research: in trials of chronic musculoskeletal pain, exercise that was allowed to hurt did at least as well as exercise kept pain-free6.
What to cut first
Not all running loads the Achilles equally. Uphill running and faster running are the usual provokers, so they go first. If the tendon is very irritable, running volume often has to come down by about half or more for 2 to 6 weeks1.
- Hills, including hilly routes you think of as easy.
- Intervals, strides and anything faster than easy pace.
- Total distance, if the morning check still fails.
Then find your current tolerance by testing it. Say 5 km leaves a pain of 2 that is gone by the evening, while 6 km pushes it to 5 and the tendon is stiffer the next morning. Your dose right now is around 5 km. That number moves as the calf gets stronger, so retest it every couple of weeks.
Change one thing at a time. If you add distance, keep the pace easy and the route flat, so you know which change the tendon objected to.
Build calf strength before speed
Pain usually settles before strength returns. In Achilles tendinopathy, maximal calf strength is typically 16 to 44% below normal, while calf endurance is only about 8% down. The good side is often weaker than it should be as well1. Twenty easy heel raises can feel fine while the calf is still a long way from ready for hills.
Which programme you follow matters less than whether you do it.
This is how we build it with runners:
- If heel raises hurt too much to do, start with holds. Rise onto your toes and stay at a height that feels acceptable. Most people only need this stage briefly.
- Move to slow heel raises as soon as they're tolerable, 2 to 3 seconds up and 2 to 3 seconds down. Do them with the knee straight and with the knee bent, because the bent-knee version works the soleus, the largest calf muscle1.
- Add weight with a backpack, dumbbells or a calf raise machine, heavy enough that each set ends at an effort of 8 or 9 out of 10. Two to three sessions a week is enough1.
- Work towards a number. For recreational runners, a seated single-leg calf raise with about 1.5 times body weight for six repetitions, or half your body weight added on a standing single-leg raise, is a useful target before running fully and hopping1.
Running is a series of springy single-leg hops, so the calf also has to handle fast loading. Once strength is near the target, add low pogo hops on two legs, then one. Build the number of hops before their height. Hopping loads the tendon harder than calf raises, so it gets the same next-morning check1.
How long it takes
Change starts early. Full recovery is measured in months.
Across 24 studies of loading programmes for midportion Achilles tendinopathy, improvement showed up as early as two weeks and peaked around 12 weeks, at about 21 points on the VISA-A8. A change of 14 points is roughly where people start to notice a meaningful difference1.
Twelve weeks is where most trials stop, and most tendons aren't finished by then. Recovery commonly takes 6 to 12 months1. Among Dutch recreational runners who developed new Achilles pain around a running event, one in three still had symptoms a year later9.
The longer view is better. In a five-year follow-up of patients treated with exercise alone, 80% had fully recovered10.
When to get it looked at
A sudden pop or a loss of push-off needs a medical assessment the same day. The other signs point to causes that need a different plan, such as inflammatory joint disease or a medication side effect1.
For everything else, the work is finding the right dose and sticking with it for long enough. A physiotherapist who works with runners can take much of the guesswork out of that.