02/18/2026
Why Your Tendon Pain Isn’t Just "Inflammation": 5 Surprising Truths from Modern Science
1. The "Rest and Ice" Trap
If you have struggled with chronic pain in your Achilles, rotator cuff, or knee, you have likely followed the traditional script: rest it, ice it, and wait for the "inflammation" to subside. It is a frustrating cycle. You do everything right, the pain fades slightly, but the moment you return to your sport, the burning ache or stiffness returns.
The reason this approach fails is because of the "Inactivity Trap." Modern clinical science has revealed that inactivity markedly decreases collagen turnover. When you stop moving, you aren't just resting; you are sending a biological signal to your body that the tendon tissue is no longer needed. This causes a decline in tissue quality and capacity. Our understanding of tendon health has undergone a massive shift, moving away from the old "tendinitis" (inflammation) myth toward the evidence-based reality of tendinopathy.
2. Takeaway #1: It’s Not Tendinitis—It’s Tendinopathy
For decades, we blamed "tendinitis," a term implying that simple swelling was the culprit. However, the structural reality of a painful tendon is much more complex than a bit of heat and redness. Research shows that a diseased tendon is in a state of matrix disrepair rather than acute inflammation.
In a healthy tendon, the extracellular matrix is a well-organized network of Type I collagen fibrils, which are strong and aligned to handle force. In a tendinopathic tendon, these fibers become fragmented and disorganized. The body attempts to fix the damage by laying down Type III collagen, which acts as a haphazard, inferior "patch." This Type III collagen lacks the biomechanical strength of the original tissue, leading to a tendon that is thick, disorganized, and less capable of handling load.
"Tendinopathy describes a spectrum of changes that occur in damaged and diseased tendons, leading to pain and reduced function. Tendinopathy is characterized by abnormalities in the microstructure, composition and cellularity of tendon."
3. Takeaway #2: Your Scans Don't Always Match Your Pain
One of the most confusing aspects of tendon health is the "Imaging Paradox." Ultrasound or MRI scans often show "tendinosis" (degeneration) in people who feel zero pain. Conversely, you can have significant pain with a relatively "normal" scan.
We now know that by the time you feel that first "twinge" of pain, structural changes have likely been occurring silently for years. Research using the carbon-14 bomb pulse method suggests that up to 50% of the collagen in a diseased matrix has undergone continuous, slow turnover long before clinical symptoms appear. Pain often represents the late phase of a prolonged disease process.
Because of this, recovery is a marathon, not a sprint. While your pain might subside in a few weeks, the structural recovery of the collagen matrix can take 24 weeks or more to show meaningful change.
4. Takeaway #3: It’s Not Just Overuse—Genetics, Meds, and Metabolism Matter
We often blame a sudden increase in running or lifting for our injuries. While "overuse" is a major trigger, your tendon’s ability to repair itself is influenced by your systemic health. If your "mechanic" only looks at your running shoes and ignores your internal biology, you may never fully recover.
The source material identifies several surprising non-mechanical risk factors:
* Genetics: Specific variations in genes, such as polymorphisms in COL5A1, significantly modify your risk of Achilles tendon pathology.
* Medications: Certain drugs are toxic to tendons. Fluoroquinolone antibiotics are associated with a 2–15% increased risk of tendinopathy and rupture, while excess corticosteroid use can impair physiological healing.
* Metabolic Factors: Conditions like diabetes mellitus, obesity, and hypercholesterolemia (high cholesterol) don't just increase your risk of injury; they actively impair your body’s response to physical therapy.
Reflection: If you have high cholesterol or metabolic issues, your rehab might take longer. Tendon health isn't just about how much you move; it is about your body’s systemic capacity to manage tissue repair and homeostasis.
5. Takeaway #4: Rest is Rarely the Cure (Loading is the Medicine)
The most counter-intuitive truth in modern sports medicine is that inactivity is a signal for weakness. To rebuild a tendon, you must use it. The gold standard of care is now "Tendon Loading Programs," with a specific focus on Heavy Slow Resistance (HSR) training. HSR has been shown to produce high patient satisfaction and, crucially, can actually shift fibril morphology back toward a near-normal appearance.
* The Pain Monitoring Model: Unlike other injuries where pain is a "stop" sign, successful tendon rehab often allows for some discomfort. Clinicians use a "pain monitoring model" where manageable pain (often up to a 4 or 5 out of 10) is allowed during exercise, provided it settles within 24 hours. This discomfort is often necessary to stimulate the tenocytes to produce new, healthy Type I collagen.
"Currently, exercise regimens, referred to as tendon loading programs, remain the most effective conservative approach in the treatment of tendinopathy."
6. Takeaway #5: The Truth About "Quick Fixes" (Injections and Surgery)
When pain persists, many patients look for a "fix" through injections or surgery. However, the modern clinical specialist views these with extreme caution:
* Corticosteroid Injections: These are often a trap. While they may provide transient pain relief (under 6 weeks), they can worsen the condition over 9–12 months. More alarmingly, evidence shows they increase the risk of re-tear rates and even spontaneous tendon rupture in the long term.
* Surgery: For many common issues, such as the shoulder, the mainstay procedure known as Arthroscopic Subacromial Decompression (ASAD) has been put to the test. Multiple multi-centre trials found that ASAD was no better than "sham surgery" (placebo) or structured physiotherapy.
Tendon healing is a slow biological process, not a mechanical "repair." Because tendons have a naturally slow turnover rate, full recovery typically requires 6 to 12 months of consistent, progressive loading.
Conclusion: A New Path Forward
Recovery requires moving away from the "passive" approach of waiting for the pain to stop or seeking a quick shot. Instead, you must adopt an "active" approach that views the tendon as a living, responsive structure that requires specific signals to grow stronger.
Closing Thought: If your tendon is a living structure that adapts to the demands you place on it, are you giving it the right signals to grow stronger, or just waiting for a ‘fix’ that may never come?
If you'd like to learn more about a tendon loading program that would work for you, please reach out. I'd be happy to help.