Why Tendon Injuries Take So Long to Heal (and What Actually Works in Rehab)

If you’ve ever dealt with a tendon injury, maybe Achilles pain while running, patellar tendon pain from jumping, or even elbow pain from throwing — you probably noticed something frustrating: it takes forever to heal.

Compared to muscle pulls or joint sprains, tendon injuries seem to drag on for weeks, sometimes months. Athletes often ask me:

“Why does this take so long?” “Am I doing something wrong in rehab?”

The truth is, you’re not broken. Tendons just play by a different set of rules than muscles and the good news is, there’s a proven way to rehab them.

Why Tendons Heal More Slowly Than Muscles

Muscles have a rich blood supply. That means when you strain a muscle, oxygen and nutrients rush in quickly to start the repair process. Most muscle injuries heal in a matter of weeks.

Tendons, on the other hand, don’t have nearly as much blood flow. Less circulation = slower delivery of healing nutrients. That’s one reason tendon pain tends to linger (Abate et al., 2009).

And unlike muscles, tendons don’t just need to “heal.” They need to be retrained to handle force again, especially if you’re a runner, triathlete, or baseball player asking your tendons to store and release energy thousands of times per game or training session.

Why Rest Alone Doesn’t Work

A common mistake athletes make is thinking rest will solve the problem. Sure, a few days of unloading can calm pain down… but tendons don’t remodel or get stronger from rest.

What they do respond to? The right kind of loading. Research shows that progressively loading a tendon helps it adapt, rebuild strength, and return to its job of handling high forces (Malliaras et al., 2013).

The Role of Isometrics and Eccentrics

So what does the “right kind of loading” actually look like?

🔹 Isometric Loading - This is when you contract a muscle without moving the joint, like holding a wall sit or pushing against an immovable object.

• Helps reduce tendon pain in the short term.

• Gives athletes a way to keep training early in rehab.

• Shown to decrease pain in patellar tendinopathy (Rio et al., 2015).

🔹 Eccentric Loading - This is when the muscle lengthens under tension, like slowly lowering during a calf raise or squat.

• Improves tendon structure and tolerance to load.

• Builds resilience for running, cutting, and jumping.

• Considered a gold-standard in Achilles and patellar tendon rehab (Malliaras et al., 2013).

A well-designed program usually starts with isometrics to calm things down, then progresses to eccentric and heavy slow resistance exercises to rebuild true tendon strength.

How Long Does It Really Take?

This is the part most athletes don’t want to hear: tendon rehab isn’t quick. While a muscle strain might feel better in 3–4 weeks, tendon recovery often takes 8–12+ weeks, depending on how long the injury has been brewing and what demands your sport places on it.

But here’s the flip side… if you stay consistent with the right loading, you’ll often come out stronger than before and less likely to have the same problem again.

Final Thoughts

If you’re battling tendon pain, remember:

• Healing is slower than muscle injuries (and that’s normal).

• Rest alone won’t solve it.

• Isometric and eccentric loading are your best friends.

• With the right plan, you don’t only recover but return stronger.

  
  

At Rival PT, we guide athletes through this process every day. It’s not always fast, but it’s worth it when you can run, throw, or compete again pain-free.

Ready to turn frustration into a comeback? Reach out, we’ll help you build the plan.