Tendonitis vs. Tendinosis

Tendonitis vs. Tendinosis: A Simple Breakdown 

If you’ve ever dealt with nagging pain in a tendon, whether in your elbow, shoulder, knee, or ankle, you may have heard the term tendonitis. But you may also have heard another term that sounds similar: tendinosis. These words are often used interchangeably, even in healthcare settings, but they actually describe two distinct stages of tendon injury, and understanding the difference matters for treatment and recovery.

This article breaks down tendonitis and tendinosis in clear, practical terms so you can better understand what’s happening in your body, why specific treatments help (and why some don’t), and what steps support recovery.

 

What Are Tendons? 

Tendons are strong connective tissues that attach muscle to bone. They act like cables that transmit force when a muscle contracts; the tendon helps pull the bone to create movement.

Tendons need to be:

• Strong enough to handle load
• Flexible enough to move smoothly
• Healthy enough to repair and adapt when stressed

Problems arise when the amount of stress on a tendon exceeds its capacity to heal and recover.

 

Tendonitis: The Irritated Stage 

Tendonitis refers to inflammation of a tendon. The suffix “-itis” literally means inflammation.

This is often the early or acute stage of tendon pain. It typically develops after a sudden increase in activity or after a specific overuse event, for example:

• Starting a new workout program
• Suddenly increasing running mileage
• Repetitive gripping or lifting at work
• A weekend of yard work after a long winter indoors

In this stage, the tendon is irritated but not yet structurally damaged.

Common signs of tendonitis:

• Sharp or warm pain in the tendon
• Swelling or mild puffy appearance
• Pain that improves with rest
• Symptoms that began recently (days to a few weeks)

Because tendonitis is inflammatory, treatments like rest, ice, and short-term anti-inflammatory medication can be helpful in this stage.

However — and this is key — tendonitis often progresses into something different if the underlying stress-load imbalance isn’t addressed.

  

Tendinosis: The Degenerative Stage

Tendinosis refers to chronic degeneration or breakdown of a tendon. The suffix “-osis” means condition or abnormal state. 

This happens when the tendon has been irritated for weeks or months, and the body has not repaired it effectively. Instead of inflammation, the tendon begins to show:

• Disorganized collagen fibers
• Thickening or stiffness
• Reduced blood flow
• Small micro-tears that haven’t healed properly
• Decreased ability to tolerate load

Common signs of tendinosis:

• Dull, aching pain
• Stiffness, especially in the morning or after rest
• Pain during activity that sometimes warms up and feels better temporarily
• Symptoms that last more than 6–8 weeks
• No visible swelling, because inflammation is no longer the main issue

In tendinosis, the problem is not inflammation. It is tissue degeneration. 

This means ice and anti-inflammatory medication are usually not very effective at this stage, because they don’t repair tendon structure.

 

Why This Distinction Matters

Understanding the difference changes treatment strategy. 

• If inflammation (tendonitis) is the issue → reduce irritation and calm the tissue.
• If tissue degeneration (tendinosis) is the issue → the tendon needs gradual mechanical loading (exercise-based repair) to stimulate healing.

Many people mistakenly continue to rest, ice, and stretch tendinosis and see little improvement. Others try to push through pain aggressively, which can worsen degeneration.

The key is knowing which phase you’re dealing with.

 

So, How Do Tendons Heal? 

Tendons respond to mechanical load. This means they adapt when they are challenged slowly, progressively, and specifically.

For tendinosis, the most researched and effective treatment approach is progressive loading exercise, such as:

• Eccentric exercises
• Heavy, slow resistance training
• Isometric loading for pain modulation 

These exercises stimulate:

• Collagen realignment
• Increased tendon stiffness (in the good way)
• Improved blood flow and tissue metabolism
• Stronger tendon structure over time

This is why many tendinopathy rehabilitation programs involve guided strengthening rather than stretching alone.

 

Tendonitis, Tendinosis, and Common Body Areas 

These conditions commonly occur in:

• Achilles tendon (Achilles tendinopathy)
• Patellar tendon (“jumper’s knee”)
• Rotator cuff tendons (shoulder pain)
• Lateral elbow tendon (“tennis elbow”)
• Medial elbow tendon ("golfer's elbow")
• Wrist tendons (repetitive strain)
• Plantar fascia (functionally similar tissue in the foot)

Different tendons respond differently to loading programs based on:

• Tissue thickness
• Blood supply
• Activity demands

This is why a one-size-fits-all exercise sheet is rarely effective.

 

When Do You Need Help?

Seek professional evaluation if:

• Pain lasts longer than 2–4 weeks
• Pain keeps returning with activity
• Pain affects your ability to work or exercise
• You’re unsure how to load the tendon safely
• You suspect you are dealing with tendinosis rather than tendonitis

An accurate diagnosis guides the right plan.

  

How Clinicians Help Restore Tendon Health

A clinically guided tendon rehabilitation plan may include:

• Evaluation of movement and load patterns
• Activity modification (but not total rest)
• Progressive loading exercises tailored to the tendon
• Soft tissue or joint mobility work where relevant
• Education on tissue healing time (weeks to months, not days)

Additional supportive treatments may include:

• Dry needling
• Manual therapy
• Shockwave therapy

But the cornerstone in tendinosis recovery is progressive loading.

 

Key Takeaways

• Tendonitis = inflammation. Usually early-stage. Responds to load reduction and calming strategies.
• Tendinosis = degeneration. Usually chronic. Requires loading-based rehabilitation to stimulate tendon repair.
• Rest alone does not resolve tendinosis.
• The most effective long-term approach for tendon health is smart, progressive strengthening, guided by someone who understands tendon adaptation.

With the right plan, most tendon problems can improve significantly, and many people return to full activity with better tendon capacity than before the injury.