Achilles Pain! Is It Tendonitis or Tendinopathy?

So, you have pain in your Achilles. My bet is that—if you’ve gone to see a professional about it—you were told it’s “tendonitis” because that’s the big ticket word that gets thrown around the blogosphere. After all, what else could it be?

Surprise! Not everything that happens to tendons is tendonitis. You could also have a tendinopathy (sometimes called tendinosis). So which is it? Tendonitis or tendinopathy? Let's break down what's going on—and why understanding the difference between tendonitis and tendinopathy can save you a lot of pain (literally).

Tendonitis: Everyone’s Favorite Diagnosis (To Give)

Tendonitis is what happens when your tendon is hit with an acute overload. (Think: pushing your body a little too hard, a little too fast). The result? Your Achilles tendon gets angry, swollen, and inflamed. It probably feels like a rusty door hinge whenever you try to move it. That “sticky” or “creaky” feeling in your tendon? Dead giveaway for tendonitis.

The best course of action? Rest. No running for 5-7 days—seriously. If you keep pushing, you’re just adding fuel to the fire. Let the inflammation settle down before you lace up again. And skip the ice and anti-inflammatory meds. For us 90s kids, that was the go-to prescription, but new research shows they can actually slow down the healing process. Your best bet? Let your body do its thing.

Tendinopathy: The Sneaky Culprit You’ve Never Heard Of

But here’s the kicker: a lot of the time, that Achilles pain you’re feeling isn’t tendonitis. It’s tendinopathy (or tendinosis). Unlike tendonitis, which hits you hard and fast, tendinopathy is a slow burn. It builds over time—sometimes months, sometimes years—sneaking up on you until you finally push it just a bit too far.

When you’re pushing yourself during training, you’re inflicting micro-damage on your tendons. Tendinopathy happens when the tendon doesn’t have the time to heal properly between those training blocks. Imagine the tissue in your tendon as a perfectly organized tree trunk, with its fibers lined up in neat layers, and with enough time, they heal back in those neat layers. But when you overtrain, those fibers start breaking down and then repair themselves in a disorganized jumble— all crisscrossed and disorganized (think waffle fry instead of tree trunk). And as you can guess, a tendon shaped like a waffle fry doesn’t handle stress as well. The more those fibers jumble, the more micro-tears you get, and the longer it can take for you to undo the process.

What Does That Mean for Your Recovery?

Tendonitis and tendinopathy both require rehab, but the approach will look different for each.

For tendonitis, rest is best—but not necessarily “full rest.” We’re talking about rest from the specific sport or activity that caused the tendonitis to begin with. Active recovery and targeted rehab can still be beneficial. It’s crucial to get guidance from a professional on what to rest and what to modify. Since tendonitis is an acute injury, you’ll need some time off to let that inflammation cool down.

Tendinopathy requires a longer-term strategy. Proper load management and a good rehab program can help reorganize those tendon fibers and get you back to running stronger. What does that mean? It means you need to load the fibers properly to reorganize them. This involves strength exercises at the right dose to stress the tendon just enough to promote healing—without making things worse. It’s best to work with a licensed professional to get you started. On the bright side, your rehab may also include your sport or activity in some capacity.

And don’t forget, you don’t have to figure this out on your own. We’re here to help you navigate what’s happening to your body and what to do next.