Tendons don't heal with rest. They heal with load.

Root Physical Therapy

Clinical Note — No. 07

Tendon Health

Tendons don't heal with rest.
They heal with load.

You rested it. It felt better. You went back — and within two weeks it hurt again. That cycle isn't bad luck. It's what happens when the treatment misunderstands the tissue.

Georgetown, Seattle11 min readEvidence-based

Written by the Doctors of Physical Therapy at Root Physical Therapy — on-site inside Root Strength, Georgetown. Tendon rehab is a dosing problem, which means it needs equipment and someone adjusting the dose week to week. We have a full gym on the other side of the door. If this sounds like your Achilles, knee, elbow, or shoulder, book an assessment — no referral needed in Washington.

You've probably already been given both of the unhelpful answers. One says rest it — so you stop, the pain fades, you go back, and within two weeks you're exactly where you started. The other says push through it, which works right up until it doesn't.

Both answers come from the same mistake: assuming a painful tendon is an injured tendon that needs to be left alone until it knits back together. That isn't what's happening in there. Here's what the tissue is actually doing, what the trial evidence supports, and what a real course of tendon rehab looks like.

One

It isn't inflamed. It's under-conditioned.

For most of the twentieth century this was called tendinitis — the "-itis" meaning inflammation. Then researchers started looking at tissue samples from painful tendons and mostly didn't find the classic inflammatory cells they expected. What they found instead was structural: disorganised collagen, increased ground substance, and new blood vessels growing into tissue that shouldn't have many.

The name changed to tendinopathy — literally "tendon pathology," a deliberately neutral term — because the old one was pointing treatment in the wrong direction. If the problem is inflammation, you rest and take anti-inflammatories. If the problem is disorganised, under-conditioned tissue, rest is close to the worst thing you can do.

Healthy Tendon vs. Tendinopathy

Figure 01

Left: healthy tendon. Collagen fibres run parallel and tightly bundled, aligned along the direction of pull — that alignment is what makes a tendon strong. Right: tendinopathy. Fibres are disorganised and separated, with new blood vessels (and the nerve fibres that travel with them) growing into tissue that normally has few. Structurally weaker, and painful — but not inflamed.

Diagram: Root PT

This is also why the tissue hurts out of proportion to how it looks on a scan. Those new vessels bring nerve fibres with them, which is a reasonable explanation for why a structurally minor change can be so persistently painful — and why the size of the change on imaging correlates poorly with how much it bothers you.

Two

Where your tendon is on the continuum

Tendinopathy isn't one condition — it's a spectrum, and where you sit on it changes what the right programme looks like. This is the Cook & Purdam model that reframed the field:

The Tendinopathy Continuum

Figure 02

Overloaded onceOverloaded repeatedlyStructurally changed

i · Reactive

The tendon swells to cope

A short-term thickening response to a load spike — a sudden jump in mileage, a new sport, an unaccustomed session. Reversible — settle the spike, keep the tendon working, and it recovers.

ii · Dysrepair

Healing, but disorganised

The tendon attempts repair and does it badly: collagen laid down out of alignment, matrix breaking down. The window where structured loading changes the trajectory most.

iii · Degenerative

Islands of changed tissue

Sounds final; isn't. Degenerative areas sit surrounded by normal tendon that adapts perfectly well — you train the healthy tissue, not the hole.

Why this matters clinically: a reactive tendon needs the spike taken out of the load; a degenerative one needs capacity built into the tissue around it. Generic advice fails because it prescribes the same thing to both — and the same thing usually turns out to be rest.

One thing worth sitting with: the degenerative end of the continuum isn't a verdict. A tendon can carry visible degenerative change and be completely pain-free — this is well documented in people with no symptoms at all. The goal of rehab was never to make the picture look normal. It's to build enough capacity in the tendon that the change stops mattering.

Three

Why rest keeps failing you

Tendon is mechanoresponsive tissue: it builds and maintains its structure in response to being loaded, and it detrains when it isn't. That single fact explains the whole frustrating pattern.

When you rest, the irritation calms down and the pain genuinely improves — so it feels like it worked. But underneath, capacity has been falling the whole time. So you return to the activity that caused the problem with a tendon that now tolerates less than it did before. It flares again, faster. You rest again, longer. Each cycle leaves you a bit further behind.

Rest doesn't rebuild capacity. It just pauses the argument.

Notice what this means about the original cause. Tendons don't usually break down because load is bad for them — load is what keeps them healthy. They break down when load increases faster than the tissue can adapt to it. The problem is almost always the spike, not the training. Which is why the answer isn't less load forever; it's the right load, delivered at a rate the tendon can keep up with.

Four

What the evidence supports

Loading is the most consistently supported treatment for tendinopathy, and it has been for decades. The original protocol came from Alfredson's work on painful eccentric heel drops for Achilles tendinopathy, which produced results good enough to change practice worldwide.

The refinement since then is that the eccentric part appears not to be the magic ingredient. A randomised controlled trial comparing eccentric training against heavy slow resistance training in patients with chronic midportion Achilles tendinopathy found both produced positive, equally good, lasting clinical results. Patient satisfaction tended to be higher in the heavy slow resistance group at 12 weeks, and session compliance was significantly better — 92% versus 78%.

That compliance gap is the practical headline. Two protocols work equally well, and people actually finish the one done fewer times per week with heavier weight. A programme you complete beats a theoretically superior one you abandon in week four.

The Scale of the Problem

Figure 03

~30%

of musculoskeletal consultations in general practice relate to tendon disorders

10%

of recreational runners are affected by Achilles tendinopathy — and up to 24% of elite athletes

12 wks

the loading duration used in the trials — meaningful change takes months, not weeks

The timeline is worth internalising early. Tendon rehab is measured in months. People who expect two weeks quit at the point where the programme was about to start working.

Where the evidence gets uncomfortable — stated plainly

Corticosteroid injections work in the short term and appear to cost you in the long term. The landmark systematic review of randomised trials in The Lancet found strong evidence that corticosteroid injection helps in the short term, but that other treatment options were more effective in the intermediate and long term. Pain and function at intermediate and long-term follow-up were worse in the corticosteroid groups. That doesn't make injection never appropriate — but it does mean an injection is buying relief now against a worse position at twelve months, and you deserve to be told that before you consent to it.

PRP is not settled. Evidence for platelet-rich plasma in tendinopathy remains inconsistent — some trials favourable, others showing no benefit over placebo, with wide variation in how the product is prepared. It isn't a substitute for a loading programme.

Isometrics are useful, not curative. Early findings suggesting isometric holds produce reliable immediate pain relief haven't replicated cleanly. We still use them, because for some people they genuinely settle a session enough to train — but as a tool inside the programme, not the programme itself.

Five

The pain-monitoring rule

Here's the question every patient asks, and the one most advice dodges: am I allowed to train if it hurts?

The answer from the research is yes — within limits, and provided it settles. Silbernagel's randomised trial let one group continue running and jumping throughout rehab under a pain-monitoring model while the other group rested from those activities for six weeks. The finding was that continued tendon-loading activity, monitored this way, did not compromise the outcome. The rules were specific:

Training With Acceptable Pain

Figure 05

0

1

2

3

4

5

6

7

8

9

10

Safe

Train normally. Pain in this range during loading is acceptable and expected.

The ceiling

Five is the limit. Hold the load — don't progress this week.

Too much

Reduce the dose. Above 5, you're adding irritation faster than adaptation.

The second rule —

Pain should have settled by the next morning, and pain and stiffness should not climb from week to week. If either is creeping up, the dose was too high — regardless of how it felt in the moment.

This is the opposite of both "no pain, no gain" and "stop if it hurts." It's a dosing instrument — and it's what makes it possible to keep training while you rehab, instead of putting your life on hold for three months.

Six

The protocol — what PT actually does

A course of tendon care at Root PT isn't a handout of three exercises. It's five pillars, sequenced by what the assessment finds and adjusted every week as capacity changes.

The Five Pillars

Figure 04

I

Assessment — including the load history

Where you sit on the continuum, what the tendon currently tolerates, and critically what changed in the six weeks before it started hurting. New shoes, a new class, a return after time off, a mileage jump. The spike is almost always findable, and finding it is what stops the problem recurring.

II

Settle the irritation without stopping

Temporarily reduce the specific provocative element — usually the fast, springy, compressive one — while keeping everything else going. This is a modification phase, not a rest phase. Isometrics live here if they help you train.

III

Build capacity — heavy, slow, progressive

The main event, and the part most people never get to. Heavy slow resistance or eccentric loading, progressed weekly against the pain-monitoring rules. Weight goes up as tolerance goes up. This is why tendon rehab needs a gym rather than a resistance band.

IV

Restore the spring

Strength alone doesn't return you to running, jumping, or sparring — tendons store and release energy, and that quality has to be rebuilt deliberately. Energy-storage and plyometric work, added last, once the tissue has the strength to handle it.

V

Manage the load that got you here

The programme fails if you return to the same weekly spike that caused it. We plan the ramp back — volume, intensity, and frequency — and coach it on the floor. Having a full gym on-site is what makes weekly dose adjustment practical rather than theoretical.

Sequencing is individual. A reactive tendon in a runner three weeks into a mileage build needs a very different order of operations than a degenerative tendon that's been grumbling for two years.

The reframe that helps most

Your tendon isn't fragile. It's under-prepared for what you're asking of it. Those are completely different problems with opposite solutions. Fragile things need protecting; under-prepared things need preparing. Almost everything in the protocol above serves that one aim — raising the ceiling of what the tissue tolerates, at a rate it can keep up with.

Seven

When it isn't tendinopathy

Most persistent tendon pain is tendinopathy and responds to loading. Some doesn't, and a few presentations need a physician rather than a rehab programme.

See a physician promptly if you have

Loading is the right first step for most tendon pain — but these need medical evaluation first:

A sudden pop or snap with immediate loss of function

Inability to push off, raise the heel, or lift the arm at all

Recent fluoroquinolone antibiotics with new tendon pain

Multiple tendons painful at once, or morning stiffness lasting hours

Significant night pain, fever, or unexplained weight loss

Marked swelling, redness, or heat over the tendon

A word about your scan

Imaging findings in tendons are common in people with no pain at all — which means a report describing degeneration or a partial-thickness tear doesn't by itself explain your symptoms, or dictate the treatment. Scans are useful for ruling specific things in or out. They're poor at telling you how much trouble you're in. We cover this properly in our note on imaging.

Eight

The bottom line

Tendinopathy is one of the few conditions where the intuitive treatment and the correct treatment point in opposite directions. Pain says protect it. The tissue needs the opposite: graded, progressive, uncomfortable-but-tolerable load, applied consistently for longer than you'd like.

That's genuinely hard to self-administer, and it's the reason so many people cycle through years of flare-and-rest. Not because they lacked discipline — because nobody gave them the dose, or adjusted it as they changed. That adjustment is the entire job.

The Short Version

• It isn't inflammation. "Tendinitis" became "tendinopathy" because the tissue is disorganised and under-conditioned, not inflamed.
• Rest lowers capacity while it lowers pain — which is why the problem returns faster each time.
• Load is the treatment. Eccentric and heavy slow resistance both work; HSR had better compliance and early satisfaction.
• Pain up to 5/10 during loading is acceptable, provided it settles by the next morning and doesn't climb week to week.
• Corticosteroid injections help short-term and are associated with worse long-term outcomes — a real trade-off you should be told about.
• The spike is the cause, not the training. Find what changed six weeks before it started hurting.
• Expect months, not weeks. The trials ran twelve weeks of loading — people who quit at three never see the effect.

This article provides general educational information and is not medical advice or a substitute for individual assessment. Persistent tendon pain should be evaluated by an appropriate healthcare provider, and any red-flag symptom warrants prompt medical attention.

Get the dose right.

Tendon rehab is a loading programme that changes every week — which needs equipment and someone measuring the response. Our clinic sits inside a full gym in Georgetown. No referral required in Washington, most major insurance accepted, and we verify your benefits before scheduling.

Book an Assessment

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Sources

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2. Alfredson H, Pietilä T, Jonsson P, Lorentzon R. Heavy-load eccentric calf muscle training for the treatment of chronic Achilles tendinosis. American Journal of Sports Medicine. 1998;26(3):360–366.
3. Beyer R, Kongsgaard M, Hougs Kjær B, et al. Heavy slow resistance versus eccentric training as treatment for Achilles tendinopathy: a randomized controlled trial. American Journal of Sports Medicine. 2015;43(7):1704–1711.
4. Silbernagel KG, Thomeé R, Eriksson BI, Karlsson J. Continued sports activity, using a pain-monitoring model, during rehabilitation in patients with Achilles tendinopathy: a randomized controlled study. American Journal of Sports Medicine. 2007;35(6):897–906.
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7. Malliaras P, Barton CJ, Reeves ND, Langberg H. Achilles and patellar tendinopathy loading programmes: a systematic review comparing clinical outcomes and identifying potential mechanisms for effectiveness. Sports Medicine. 2013;43(4):267–286.
8. Millar NL, Silbernagel KG, Thorborg K, et al. Tendinopathy. Nature Reviews Disease Primers. 2021;7(1):1.
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