Achilles Tendinopathy: Why the Fix Is Load, Not Rest

Winnipeg summers pack a lot of running and jumping into a short window. Trails open up, the river paths fill in, and mileage climbs quickly. For many people, that ramp is when a stubborn ache appears at the back of the ankle — the Achilles tendon. It is one of the most common overuse complaints we see, and it is also one of the most misunderstood.

It Is Not "Tendinitis"

For years the suffix "-itis" implied that the problem was inflammation, and that the answer was rest, ice, and anti-inflammatories. When researchers actually examined painful Achilles tendons, they found something different: disorganized collagen, changes in the tendon's ground substance, and new blood vessel growth — but little of the classic inflammatory picture.¹ That is why the more accurate term is tendinopathy. The tissue is not inflamed so much as it is disorganized and under-conditioned for the load being asked of it.

This distinction matters because it changes the treatment. If the problem were simple inflammation, rest would fix it. Because the problem is a tendon that has not been prepared for its workload, rest alone tends to make the tendon weaker and more sensitive over time. When you return to running, the pain comes back — often worse.

Why Loading Works

Tendons are living tissue that adapts to the demands placed on them. Load them progressively and they remodel: the collagen reorganizes, the tendon gets stiffer and more capable, and pain settles. This is the foundation of the most studied approaches to Achilles rehab.

The original work came from Alfredson, who showed that a heavy eccentric calf-loading program (slowly lowering the heel off a step) produced meaningful improvements in people who had been considering surgery.² Since then, research has broadened the toolbox. Heavy slow resistance training — controlled calf raises with real load through both the lifting and lowering phase — produces comparable outcomes and many people find it easier to stick with.³ The common thread is not the exact exercise. It is progressive, substantial load applied consistently over time.

This is where a principle we come back to often applies. As Tim Gabbett put it, there are no bad exercises — only too much too soon.⁴ The Achilles does not fail because someone ran. It becomes irritated when the workload climbs faster than the tissue can adapt. The fix is not to stop loading it; it is to load it deliberately and build back up.

Using Pain to Guide You

One of the most useful shifts for people with tendinopathy is learning that some discomfort during loading is acceptable and does not signal damage. A widely used framework allows pain up to about 5 out of 10 during and immediately after exercise, provided it settles by the next morning and does not progressively worsen week to week.³ If morning stiffness and pain are stable or improving over a few weeks, the load is appropriate. If they are climbing, the load came on too fast and needs adjusting — not abandoning.

This monitoring model takes the fear out of movement. It gives you a clear, objective way to progress rather than guessing or stopping at the first twinge. If you want to go deeper on the idea that pain does not always mean tissue harm, we cover it in our post on hurt versus harm.

A Realistic Timeline

Here is the part people least want to hear: tendon rehab is measured in months, not days. Meaningful change in symptoms often takes 8 to 12 weeks of consistent loading, and full return to demanding sport can take longer.³ Tendons remodel slowly. That is not a reason for discouragement — it is a reason to start now and to stop expecting a passive fix to resolve it in a week.

A typical progression looks something like this:

• Establish a tolerable baseline of calf loading, often starting with both legs and progressing toward single-leg work.
• Add load gradually — through range, then through resistance — using the pain-monitoring rule to guide each step.
• Reintroduce running or jumping as a graded activity, not an all-or-nothing return, managing weekly volume the way you would manage any other training variable.

Look at the Whole Chain

The Achilles is rarely an isolated problem. Calf strength and capacity matter, but so do the hip, the foot, and how running load is distributed up the leg. Someone whose calf is doing extra work because the hip is not contributing will keep overloading the tendon no matter how well they rehab it locally. Assessing the whole kinetic chain — not just the sore spot — is what keeps the problem from returning. This regional-interdependence view is central to how the Boreal team approaches stubborn lower-limb injuries.

If your Achilles has been grumbling as your summer mileage climbs, the takeaway is straightforward: the tendon needs to be loaded well, not shut down. Rest may quiet the symptom briefly, but a graded loading program is what changes the tissue and gets you back to running with confidence. You can also apply the same load-management thinking preventively, which we outline in our piece on managing training load.

References

1. Khan KM, Cook JL, Kannus P, Maffulli N, Bonar SF. Time to abandon the "tendinitis" myth. BMJ. 2002;324(7338):626-627.
2. Alfredson H, Pietila T, Jonsson P, Lorentzon R. Heavy-load eccentric calf muscle training for the treatment of chronic Achilles tendinosis. Am J Sports Med. 1998;26(3):360-366.
3. Beyer R, Kongsgaard M, Hougs Kjaer B, Ohlenschlaeger T, Kjaer M, Magnusson SP. Heavy slow resistance versus eccentric training as treatment for Achilles tendinopathy: a randomized controlled trial. Am J Sports Med. 2015;43(7):1704-1711.
4. Gabbett TJ. The training-injury prevention paradox: should athletes be training smarter and harder? Br J Sports Med. 2016;50(5):273-280.