There is a pattern so characteristic that experienced clinicians recognize it from the description alone.
You are stiff and sore for the first few minutes of a run.
Then it eases. By a mile or two in, you barely notice it. You finish the run thinking it is improving.
Then you get up the next morning and the first few steps to the bathroom are considerably worse than the day before.
That sequence is the signature of Achilles tendinopathy, and the reason it catches so many runners out is that the warm up effect gets interpreted as evidence that running is helping.
It is not. It is just what tendons do.
Where It Is Matters Enormously
Before anything else, identify the location, because two conditions share a name and need different treatment.
Midportion tendinopathy sits in the tendon itself, roughly two to six centimeters above where it attaches to the heel bone. You can usually pinch the tender area between your fingers.
Insertional tendinopathy sits right at the back of the heel bone where the tendon attaches, often with tenderness on the bone itself.
The reason this matters: the two respond differently, and in one important respect the advice is opposite.
Midportion generally tolerates loading through full range, including positions where the heel drops below the level of a step.
Insertional does not. Dropping the heel below horizontal compresses the tendon against the bone, and that compression tends to aggravate insertional problems. Programs for insertional tendinopathy typically avoid it, and frequently use a small heel raise.
So doing the standard eccentric heel drop off a step is reasonable for one and frequently counterproductive for the other.
This article is mainly about the midportion version.
What Is Actually Happening
The language matters here because it changes the treatment.
The old term was tendinitis, implying inflammation. When researchers have examined tendon tissue in persistent cases, what they find is not primarily an inflammatory process. It is a change in the structure of the tendon, with disorganized collagen and altered tissue properties.
Which is why clinicians now generally say tendinopathy, and why the implications differ.
If the problem were inflammation, rest and anti inflammatories would resolve it.
If the problem is a tendon that has lost its capacity to tolerate load, then rest, which reduces capacity further, is working against you.
That explains the most common failed strategy in running. Rest for three weeks, symptoms settle, return to running, symptoms return within two weeks and often faster. The rest did not fix anything. It removed the load while reducing the tendon’s ability to handle it.
The Treatment That Works
Tendons adapt to load. The treatment is loading, applied progressively.
The best known protocol involves heel raises and controlled lowering, performed both with the knee straight and with the knee bent, since those target different parts of the calf complex.
The classic version is three sets of fifteen repetitions of each, performed twice daily, over twelve weeks. That is a substantial commitment and it is the dose that was studied.
Load is added over time, typically with a weighted backpack, once bodyweight becomes manageable.
An alternative approach, heavy slow resistance, uses fewer sessions with heavier loads and slower tempos, performed roughly three times a week. Outcomes appear broadly comparable, and many people find the lower frequency considerably easier to sustain, which matters because adherence determines results.
Either way, the principles are the same:
Slow and controlled, not fast.
Loaded enough to be genuinely demanding by the final repetitions.
Progressed over weeks, because a program that stays the same maintains rather than builds.
And continued well past the point where symptoms ease, which is where almost everybody stops too early.
Pain During the Exercises Is Expected
This surprises people and it is important.
Discomfort during tendon loading exercises is acceptable, generally up to a moderate level. You are not supposed to avoid all pain, and doing so usually means the load is insufficient.
The measure that matters is the following morning.
Back to your usual baseline? The dose was appropriate. Continue and progress.
Clearly worse? Reduce the load by roughly 20 to 30 percent and build back more gradually.
That single rule replaces guesswork for the entire rehabilitation.
Running While You Rehabilitate
Most people do not need to stop completely, which is worth knowing because the fear of total rest is what stops people seeking help.
Reduce volume rather than stopping.
Cut the aggravating sessions first. Hills and speed work load the Achilles considerably more than easy running, and they are usually the first things to remove.
Flat, even surfaces temporarily.
And apply the next morning rule to runs as well as exercises.
Cross training with cycling or swimming maintains fitness while the tendon rebuilds.
The Timeline Nobody Wants to Hear
Expect this to take months.
Twelve weeks is a realistic minimum for a meaningful loading program, and some cases take considerably longer.
Progress is not linear. Good weeks and setbacks are both normal, and a flare in week seven does not undo weeks one through six.
And symptoms improve well before capacity does, which is precisely why the most common reason for recurrence is stopping the program around week five when things feel better.
If you have had this three times, the pattern is almost certainly incomplete rehabilitation rather than a stubborn tendon.
What Set It Up
Almost every case traces to something in the preceding weeks.
A jump in training volume. Adding hill work or speed sessions. A change in footwear, particularly to a lower drop shoe. A return to running after a break. More time in flat shoes generally. Or a period of reduced activity followed by a rapid resumption.
Identify it, because if it is still present, the tendon will meet the same demand again.
And address calf strength and ankle mobility, both of which commonly contribute and both of which are assessable.
When It Is Not Tendinopathy
Some presentations need a different look.
Sharp, pinpoint pain on bone that worsens the further you run, rather than easing after warm up. That reversal is important and warrants prompt assessment.
A sudden pop or the sensation of being struck in the back of the ankle, with difficulty pushing off or rising onto the toes. That needs urgent assessment, since Achilles rupture is frequently mistaken for a sprain.
Pain with swelling, warmth or redness in the calf, particularly without a clear injury, which needs same day medical assessment.
Numbness or tingling.
Or pain that is severe at rest and at night, not varying with activity.
Get the Program Right the First Time
Achilles tendinopathy that has lasted a year is almost always an under dosed, under progressed, or abandoned program rather than an untreatable tendon.
Shiraj Physio offers a free discovery visit at no cost and no obligation. You will get a thorough assessment of your Achilles, calf capacity, ankle mobility and training load, confirmation of exactly which type you have, and a loading program set at the right starting point with a plan for progressing it.