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That dull ache at the back of your heel when you take your first steps in the morning. The stiffness that loosens up after 10 minutes of your run, only to return as a throb the next day. If you’ve landed here, you probably already know something’s off with your Achilles — and you’re trying to figure out whether you can keep running or whether you’re about to lose weeks of training.
The honest answer is: it depends. Achilles tendinopathy is one of the more manageable running injuries if you catch it early and respond sensibly. It’s also one of the easier ones to make significantly worse by ignoring the warning signs or pushing through the wrong kind of pain. This article will help you tell the difference, understand what’s actually happening in your tendon, and give you a practical framework for deciding what to do next.
This isn’t a substitute for seeing a physio — and if you’re in significant pain, you should. But for the runner who woke up with a stiff Achilles and is wondering whether to lace up for tomorrow’s 10K, this is the clearest guide we can give you.
What achilles tendinopathy actually is
Your Achilles tendon connects your calf muscles to your heel bone. It handles enormous load — roughly 6–8 times your body weight during running. Tendinopathy (not “tendinitis”, which implies acute inflammation that’s now considered an oversimplification) refers to a breakdown in the tendon’s collagen structure, usually from repetitive overload.
There are two main types:
- Midportion tendinopathy: Pain 2–6cm above the heel bone. Most common in runners. Generally more responsive to load-based rehab.
- Insertional tendinopathy: Pain right at the point where the tendon meets the heel bone. Trickier to treat, more sensitive to stretching and compression, and slower to respond.
Knowing which type you have matters, because the rehab approach differs — particularly around whether heel drops and stretching help or aggravate the problem.
Can you keep running with achilles tendinopathy?
Often, yes — but with conditions. The key framework used by most sports physios is a pain monitoring model, developed from research by Jill Cook and Craig Purdam, two of the leading researchers in tendon rehabilitation. The principle: some discomfort during activity is acceptable; pain that spikes above a certain threshold, or that doesn’t settle down within 24 hours, is a signal to back off.
A practical version of this uses a 0–10 pain scale:
| Pain level during running | What it means | What to do |
|---|---|---|
| 0–3/10 | Acceptable | Continue running, monitor closely |
| 4–5/10 | Borderline | Shorten or slow the run, reassess next day |
| 6+/10 | Too much | Stop the run, rest that day |
| Pain worse the next morning than before the run | Overloaded | Reduce volume by 20–30% for the next 3–5 days |
The 24-hour rule is particularly useful: if your Achilles feels better or the same the morning after a run, you’re probably within a manageable range. If it’s worse, the load was too much.
The warning signs that mean you should stop
Some situations genuinely require you to stop running immediately and see a professional:
- Sudden, sharp pain in the tendon during a run — this can indicate a partial or complete rupture, which is a medical emergency. A rupture often feels like being kicked or struck from behind, sometimes with an audible snap.
- Significant swelling or visible thickening that appears quickly
- Pain at rest — tendinopathy pain should largely be activity-related; constant resting pain suggests something more serious
- No improvement after 2–3 weeks of sensible load management — at this point you need a proper assessment, not more self-management
If you’re managing insertional tendinopathy specifically, be aware that activities involving a lot of heel-cord compression (hills, incline treadmills, stretching the calf hard) can significantly aggravate symptoms. Running on flat surfaces at a moderate pace is often better tolerated than easy-looking hilly routes.
What to actually change about your running
If you’re in the “can continue with modifications” category, here’s what’s worth adjusting:
Reduce total mileage first. If you were running 40km a week, try dropping to 25–30km. Keep at least one complete rest day between runs. The tendon needs time to recover between loading sessions.
Slow down. Faster paces and hard efforts create significantly more Achilles load. An easy day at 6:00–6:30/km feels very different to the tendon compared to a tempo at 5:00/km. Keep all running easy while symptoms are active.
Avoid speedwork and hills. These are the two biggest aggravators. Flat, steady, moderate-effort running is your friend right now. That hill session can wait.
Watch your footwear. A small heel raise (even a temporary heel pad from a pharmacy) can reduce load on the tendon. It’s not a fix, but it can buy some comfort while you’re doing the actual rehab work. Don’t wear flat, zero-drop shoes during a flare-up.
Cut the stretch. Counterintuitively, aggressively stretching your calf and Achilles when you have insertional tendinopathy can make things worse by compressing the tendon at its insertion point. Midportion tendinopathy is more tolerant of stretching, but even then, avoid it immediately before running.
The rehab you actually need to do
Running modification buys you time, but it doesn’t fix the tendon. What does? Progressive loading — specifically, eccentric and heavy slow resistance (HSR) exercises for the calf complex.
The NHS recommends eccentric heel drop exercises as a core part of Achilles rehabilitation. The standard protocol involves:
- Stand on a step with your heels hanging off the edge
- Rise up on both feet, then slowly lower on the affected foot only (3 seconds down)
- 3 sets of 15 reps, twice daily
- Progress to single-leg raises once pain allows
Expect it to be uncomfortable at first — a 3–4/10 during the exercise is acceptable. The key is consistency. Research from tendon specialist Håkan Alfredson’s original work (now refined and widely adopted) consistently shows that progressive calf loading is the most effective conservative treatment for midportion Achilles tendinopathy.
This takes time. Most runners see meaningful improvement in 6–12 weeks. If you’re expecting a 2-week turnaround, you’ll likely under-do the rehab and end up back here.
How long before you’re back to normal training?
There’s no single timeline, but here’s a rough guide for someone with mild-to-moderate midportion tendinopathy who catches it early:
| Stage | Timeframe | What running looks like |
|---|---|---|
| Active irritation | Weeks 1–2 | Reduced volume, easy pace only, flat routes |
| Settling phase | Weeks 3–6 | Gradually rebuild mileage (no more than 10% per week), still no speedwork |
| Loading phase | Weeks 6–12 | Reintroduce hills cautiously, tempo runs at reduced effort |
| Return to full training | Week 12+ | Normal plan resumes if pain-free |
These timelines assume you’re doing the calf loading work consistently and not ignoring flare-ups. If you skip the rehab exercises because they feel boring (and they are), expect this to drag on longer.
Insertional tendinopathy tends to take longer — often 3–6 months for full resolution — and requires more careful management around compression positions.
When to get professional help
A sports physio should be your first call if:
- You’re not sure whether it’s midportion or insertional (the treatment differs)
- You’ve had symptoms for more than 3–4 weeks without improvement
- You have an event coming up in under 6 weeks and you need to make decisions about whether to continue
- The pain is 6/10 or above during your runs
A good physio will assess your tendon, your running mechanics, your training load, and your overall picture. They can also confirm whether this is genuinely tendinopathy or something else — Achilles bursitis, for example, or referred pain from the calf — which changes the management entirely.
You don’t need an MRI to start treatment. A clinical diagnosis from a physio is usually sufficient, and most runners do well without imaging.
The Honest Takeaway
- You can often keep running with Achilles tendinopathy, but only if pain stays at 3/10 or below during activity and symptoms don’t worsen the next morning. If either of those conditions isn’t met, back off.
- Modifying your running is not the same as treating it. You need to do the calf loading exercises — eccentric heel drops as a minimum — consistently and progressively for 6–12 weeks. Running less without doing the rehab work just delays the problem.
- Slow down, flatten the route, drop the mileage by 20–30%. Those three changes alone make a significant difference to Achilles load.
- Don’t ignore the 24-hour rule. If you feel worse the morning after a run than you did the morning before it, the previous session was too much. Adjust before the next one.
- If you’re not improving after 3–4 weeks of sensible management, see a physio. Tendons can be stubborn, and self-managing a problem that actually needs hands-on assessment will cost you more time in the long run.
Next read: Dealing with a running injury and not sure what to do next? Read our guide to running through injury vs. taking time off → /running-through-injury-or-rest