Stiffness and pain at the back of the heel, worst first thing in the morning or after sitting for a while, that warms up after a few minutes of walking. It eases during a run but flares the next morning. You rest it for a week and it feels better — then you run again and it’s back within days.
This is Achilles tendinopathy, and the rest-and-return cycle is the reason most people have it for months longer than they should. Rest does not fix it. It just postpones the pain until you load the tendon again.
What’s happening in the tendon
Tendons transfer force from muscle to bone. When cumulative load repeatedly exceeds what the tendon can recover from, the internal structure starts to break down — the organised collagen fibres become disorganised, the tendon thickens and becomes less stiff, and it becomes sensitised and painful. This is tendinopathy: not inflammation (the old name “tendinitis” implied it, but the tissue change is structural, not inflammatory).
The Achilles tendon is the largest and strongest in the body, but it has a poor blood supply — particularly in the mid-portion, about 2–6 cm above where it inserts into the heel bone. That’s why mid-portion Achilles tendinopathy heals slowly and why rest alone doesn’t drive recovery: the tendon needs load to stimulate the remodelling that restores its structure.
Why rest feels like it works but doesn’t
With rest, the tendon settles because you’ve reduced the load below the threshold that provokes it. The underlying structure hasn’t changed — it’s just not being provoked. Return to running and you’re loading a tendon that hasn’t improved its capacity, so the pain returns, often quickly. Each rest-and-return cycle without a loading program leaves you no further forward.
Mid-portion vs insertional tendinopathy
These are two distinct problems that look similar but are managed differently:
- Mid-portion tendinopathy — pain 2–6 cm above the heel bone. Responds well to progressive loading through the heel raise, including end-range dorsiflexion.
- Insertional tendinopathy — pain right at the back of the heel where the tendon meets the bone. More sensitive to compression and stretching into dorsiflexion; heel raises are done only to neutral (not beyond) in early management. Shockwave therapy has reasonable evidence for insertional Achilles.
Getting this distinction right matters for treatment — aggressive stretching of an insertional tendinopathy is one of the fastest ways to make it significantly worse.
What treatment involves
Heavy slow resistance loading
The evidence-backed core of Achilles rehab is heavy, slow heel raises — loaded progressively over weeks. “Heavy” means weighted, not just bodyweight; “slow” means a controlled 3-second up, 3-second down tempo. This approach — popularised as the Alfredson protocol and its modifications — has consistently outperformed rest in trials. It drives tendon remodelling by providing the mechanical stimulus the tendon needs to rebuild its structure. Both eccentric-only and eccentric-concentric loading work; current evidence slightly favours combining both.
Load management during rehab
Continuing to run during rehab is usually appropriate — the goal is to find a volume and intensity that doesn’t flare the tendon beyond a tolerable level. A useful guide: pain during or after a run that settles within 24 hours is acceptable; pain that is worse the next morning than the morning before means the load was too high.
Hands-on treatment
Soft tissue work to the calf complex and Achilles reduces pain and stiffness, and improves the baseline from which loading is tolerated. Dry needling to calf trigger points is useful where there is significant guarding and restriction in the calf. More on dry needling →
Shockwave therapy
For insertional Achilles tendinopathy and chronic mid-portion cases that haven’t responded to a loading program, shockwave therapy has reasonable evidence. It’s typically used as an adjunct to loading rather than a replacement for it. More on shockwave therapy and what it treats →
What to avoid
A few things that reliably make Achilles tendinopathy worse:
- Aggressive calf stretching — particularly for insertional tendinopathy; it compresses the insertion and irritates it
- Complete rest followed by return to full load — the rest-and-return cycle described above
- Massage directly on the tendon — the tendon is not the target; the calf muscle belly is
- Repeated corticosteroid injections — short-term pain relief, but evidence of tendon weakening with repeated use
How long does it take?
Mid-portion Achilles tendinopathy typically improves meaningfully within 12 weeks of a proper loading program. Insertional takes longer — 3–6 months is realistic for full resolution. Chronic cases that have been mismanaged for years take longer still, but do respond to a structured approach.
The bottom line
Achilles tendinopathy is a load tolerance problem. Rest removes the pain temporarily but doesn’t fix the tendon’s capacity. What works is progressive heavy loading — building the tendon’s structural integrity and tolerance — combined with sensible load management to keep training going without repeatedly blowing the tendon up. If yours has been going on for months, you haven’t had the right loading program yet.