The Reality of Tendon Pain

I’m sure that you felt it during a run, workout, or recreational activity — that pinpoint pain that didn’t go away with rest. You were probably told it’s tendinitis, you decided to you ice it and maybe took some medication, waiting for the symptoms to go away but when you went back to your regular scheduled programming, it was exactly the same. 

This is most likely because what most people label as tendinitis is something a bit different – tendinopathy. Tendinopathy happens when a tendon becomes overworked and underprepared for the loads that you’ll be placing on it. It’s not just inflammation, it’s a tissue that’s lost some of its strength, resilience, structure and capacity to handle the stresses that you have been exposing it to. The way to get back to your desired activities isn’t rest or medication – it’s building back up that tissue capacity through progressive, targeted loading. 

Tendinitis vs. Tendinopathy: What’s Really Going On

The term tendinitis came from the belief that inflammation was the main cause of tendon pain and this has stayed in use since. Newer evidence based research now shows that most long-term tendon pain doesn’t involve much inflammation at all but instead is a degenerative process where the collagen fibers that make up the tendon become disorganized and weaker over time. This reduces the tissue’s ability to manage mechanical stress and since that is the main function of the affected tissue, problems arise. This is why clinicians now use the vague term tendinopathy, which better explains the problem. It involves a mix of repetitive strain, poor recovery and decreased tissue capacity, rather than an inflammatory build up. In other words, tendon pain isn’t about inflammation – it’s a capacity issue. You have to progressively load it to rebuild its strength and tolerance again.

“Treat the Donut, Not the Hole”

This analogy perfectly captures how tendinopathy should be treated and has been used by Cook and colleagues. The “hole” represents the small affected part of your tendon, while the “donut” represents the surrounding healthy tissue. Instead of focusing only on repairing the damaged spot, the goal is to build strength and capacity in the healthy tissue around it. Of course you can’t pick and choose where you bias the stimulation of the tissue to occur but fortunately for us, our bodies are pretty smart and know how to do that with the proper load that you will be administering to the tissue. That delivered load is what will cause the necessary change needed to the tendon for proper reorganization and laying down new collagen.

What Tendons Actually Do

Tendons connect muscles to bones, acting as the force transmitters of the body. When a muscle contracts, the tendon pulls on the bone to create movement, absorb impact, and stabilize joints. Tendons are primarily composed of type I collagen which is organized in a rope-like structure that provides exceptional tensile strength with a bit of elasticity – the perfect formula to properly absorb daily mechanical stimulus and release energy efficiently, just how a spring does. This all happens during jumping, running, twisting, pivoting, landing and sprinting time after time. At the point where the tendon meets the bone which is called the enthesis, the tissue gradually transitions from soft to hard, distributing forces evenly and reducing injury risk. When tendons are overloaded and/or don’t recover properly, this system breaks down on a cellular level with an increase in disorganized type 3 collagen in place of type 1 which leads to pain, stiffness, and reduced performance.

Why Tendons Hurt

Healthy tendons don’t really have few pain-sensing nerves like other biological tissue in the body. When tendons are overloaded or injured, the body responds by growing new nerves into the tendon via a process called neoinnervation. These new nerve fibers release pain-related chemicals such as substance P and CGRP (calcitonin gene-related peptide), which enhances sensitivity and increases pain signals. Even when the original injury heals, these new nerves continue to remain active, keeping the tendon hypersensitive. Because of this, the pain always doesn’t match items such as imaging where some people have pain with normal scans, while others have structural changes but no symptoms. Pro tip – this is something that we see in a lot of weight bearing tissue of the body, not just with tendons but with ligaments, muscles, etc. In short, tendon pain is both mechanical and neurological, not so simply put as just “wear and tear.”

It’s Not Just About Load — Other Factors Matter

While repetitive strain is often the trigger, tendinopathy isn’t purely mechanical and that makes it that much harder to treat. There are a bunch of biological and lifestyle factors that can influence how your tendons respond to stress and how well they recover:

• Metabolic health: Conditions like diabetes, thyroid issues, and obesity can change the make up of collagen and weaken tendons.

• Inflammation around the tendon: The fat pad behind the Achilles tendon (Kager’s fat pad) can become aggravated, releasing chemicals that irritate the tendon.

• Medications: Certain antibiotics such as fluoroquinolones and corticosteroids are linked to higher rates of Achilles tendon injuries, particularly in older adults.

• Lifestyle and recovery: Lack of quality sleep, high stress, and rapid increases in training load all slow tendon healing and adaptation.

Tendinopathy is usually a combination of mechanical overload and decreased biological readiness — not just one or the other.

The Continuum Model of Tendon Healing

The Cook & Purdam Continuum Model helps describe how tendons respond to stress and injury:

1. Reactive Tendinopathy: A short-term stiffening response after a sudden jump in volume, such as a strenuous workout or rapid spike in running mileage.

2. Tendon Disrepair: The tendon structure becomes affected and is now partially disorganized but it can still return back to the reactive stage.

3. Degenerative Tendinopathy: Long-term overload leads to significant collagen breakdown and loss of elasticity which has a difficult time to return back down to tendon disrepair and the reactive stage now.

Knowing which stage you’re in helps guide treatment — early stages benefit from load modification, while chronic cases need progressive strengthening and conditioning.

Loading Is the Medicine — Getting the Dose Right

When it comes to tendons, load is the medicine, but like any medicine, the dose must be right. A reduced amount of load won’t stimulate healing/change in the collagen make up while too much too soon can cause flare ups. Rehabilitation focuses on finding the right balance — enough tension to promote adaptation without triggering set backs for the patient. Depending on where you are in your tendon continuum, you would perform different exercises for that stage.

1. Isometric Loading — Calm It Down

Isometric exercises (static holds) can decreased pain and improve short-term strength by decreasing nerve sensitivity, cortical inhibition which reduces effective firing of contractile tissue. They’re mainly used early in rehab or during competitive seasons but can become quite challenging and intense. Example: Wall-sit or mid-range calf hold

Prescription: 4-5 sets × 30-45 seconds, 1–2 times per day

Pain tolerance: Up to a 4–5 / 10 discomfort is acceptable

2. Eccentric Loading — Rebuild Structure

Eccentric loading emphasizes slow, controlled lowering during a movement — for instance, lowering your heel during a calf raise. It helps stimulates those disorganized Type 3 collagen fibers to turn into Type 1 collagen which has more optimal structure, stiffness and load tolerance. Example: Alfredson protocol for Achilles tendinopathy

Prescription: 3 sets × 15 slow reps, twice daily

Progress: Gradually add load as tolerated

3. Heavy–Slow Resistance (HSR) — Build Capacity

Once pain is under control, heavier and slower lifting helps strengthen both muscle and tendon for long-term durability. Exercises that fall under this include: Squats, calf raises, lunges, leg press, bulgarian split squats

Prescription: 3–4 sets × 6–8 reps, 3 seconds up / 3 seconds down, 2–3× per week

HSR restores the tendon’s ability to handle daily and athletic demands.

4. Plyometric / Energy-Storage Work — Restore Elasticity

The final phase rebuilds the tendon’s ability to store and release energy efficiently — essential for running, sprinting, or jumping. Progression:

Double-leg hops → single-leg hops → bounds → accelerations

Begin this phase only once strength and pain levels are well-controlled as the fundamental needs for tissue capacity need to be established prior but can be implemented with professional supervision.

What Not to Do Early On

• Don’t completely rest – probably the worst thing you can do due to as this delay further weakens the tendon if you go right back to your desired activity.

• Avoid cortisone and PRP injections. They may reduce pain short-term but slow healing and the research behind them isn’t great.

• Skip aggressive stretching. It can worsen irritation early in rehab if it is an insertional tendinopathy issue.

• Don’t rely solely on passive care. Manual therapy and other modalities can help, but progressive loading drives recovery.

When to Seek Help

If your tendon pain lasts more than a few weeks, limits walking or exercise, or keeps returning after rest, it’s time to be evaluated by a professional. A skilled physical therapist can determine the stage of your tendon condition, identify contributing movement or strength deficits, and design a graded loading plan tailored to your goals. At Perfect Stride Physical Therapy, we specialize in identifying the “why” behind tendon pain — not just treating symptoms. Our clinicians combine individualized loading programs, movement analysis, and education to help you move efficiently, perform better, and prevent recurrence.

Key Takeaways

• Tendinopathy is a load-capacity problem, not just inflammation.

• Pain doesn’t always equal damage — sensitivity plays a major role.

• Progressive loading heals tendons — isometrics, eccentrics, and HSR all matter.

• Health, sleep, and stress all influence recovery.

• Don’t just treat the damaged spot — build the healthy tendon around it.

Ready to get back to performing at your best? 

For more information, contact Perfect Stride Physical Therapy today!

Perfect Stride Physical Therapy

Website – https://perfectstridept.com/ 

Email – info@perfectstridept.com

Location: 32 Union Square East, Suite 215, New York, NY, 10003

Phone: (917) 494-4284

References & Further Reading

1. Cook JL, Rio E, Purdam CR, Docking SI. Revisiting the continuum model of tendon pathology. Br J Sports Med. 2016.

2. Cook JL, Purdam CR. The “Donut” Model of Tendinopathy Rehabilitation. Br J Sports Med. 2012; 46(10):735–736.

3. Almekinders LC, Temple JD. Etiology, diagnosis, and treatment of tendonitis. Med Sci Sports Exerc. 1998; 30(8):1183–1190.

4. Benjamin M, Kaiser E, Milz S. Structure–function relationships in tendons. J Anat. 2008; 212(3):211–228.

5. Alfredson H, Cook J. A treatment algorithm for managing Achilles tendinopathy. Br J Sports Med. 2007; 41(4):211–216.

6. Schubert TE et al. Achilles tendinosis and sprouting of substance P positive nerve fibers. Ann Rheum Dis. 2005; 64(7):1083–1086.

7. Rio E, Kidgell D, Moseley GL, Cook J. Tendon neuroplastic training. Br J Sports Med. 2016; 50(4):209–215.

8. Gehwolf R et al. Tendinopathy: The interplay between mechanical stress, inflammation, and vascularity. Adv Sci (Weinh). 2025; 12(36):e06440.

9. Pingel J et al. Inflammatory and Metabolic Alterations of Kager’s Fat Pad in Chronic Achilles Tendinopathy. PLoS ONE. 2015; 10(5):e0127811.

10. Springer C et al. Fluoroquinolones and risk of Achilles tendon disorders. Eur J Clin Pharmacol. 2019; 75(9):1217–1228.

11. Kongsgaard M et al. Corticosteroid vs eccentrics vs HSR in patellar tendinopathy. Scand J Med Sci Sports. 2009.

12. Beyer R et al. HSR ≈ Eccentrics for Achilles Tendinopathy, 12–52 weeks RCTs. ,