Stubborn Tendon Pain? Why Isometric Loading May Be the Key to Healing

Introduction - Tendon Pain Enigma

You hurt yourself—maybe playing sports, or through repetitive strain at work or home. Your doctor told you it was just a soft-tissue strain or an overuse injury, and that it should heal on its own in several weeks. But months—or even years—later, you’re still dealing with that same nagging pain. It comes and goes, flaring up with the simplest movements. Sound familiar?

Recovering from a tendon injury often feels like two steps forward, one step back. Just when things seem to be improving, a small activity can set you back again.

You’re finally on the mend… and then, out of nowhere, the pain returns. Frustrating? Absolutely. But here’s the thing—this isn’t just “bad luck.” There’s science behind why tendon injuries can be so stubborn.

Quick Summary – What You Need to Know

• Tendon pain lingers because tendons heal slowly and don’t adapt like muscles.

• Isometric loading (gentle, sustained holds) stimulates weaker tendon fibers, encouraging collagen growth and repair.

• Protocol: 4 × 30-second holds (~50% effort) with 2-minute rests. About 10 minutes per session, once or twice daily. After 8 weeks, taper to 2–3 sessions/week.

• Nutrition boost: 15–30 g gelatin or collagen + 50–225 mg Vitamin C, taken 30–60 minutes before exercise, can double collagen synthesis.

• Timeline: Relief may begin within weeks, consistent gains usually come in 1–3 months, and deeper tendon healing continues for many months with regular training.

• Next step: See my exercise video demo and handout for safe, practical examples and a full program.

Why Tendons Are Different

Unlike muscles, tendons adapt and heal slowly. Once injured, they can form scar tissue, lose elasticity, and struggle to handle everyday loads the way they once did. That’s why a quick game of pickleball, a sudden reach, or even a long day of typing can trigger a flare-up.

For decades, the belief was that once a tendon was injured, it couldn’t truly recover—that rehab was more about building up the healthy surrounding tissue to take over the work. This idea was captured in the “donut-hole” analogy: focus on the donut, not the hole.

But recent research is reshaping this view. It shows that tendons aren’t just passive tissues that wear down with time—they can remodel, adapt, and even heal when they’re given the right kind of stimulus.

A New Direction in Tendon Rehab

This is where things get exciting. Over the past few years, new studies have revealed how specific types of loading—particularly isometric exercise—can activate tendon cells, encourage new collagen production, and actually support tissue repair. Pairing this with the right nutritional strategies can make the process even more effective.

In other words, the old story of tendons being “doomed to degeneration” is being rewritten. And that’s a game-changer for anyone stuck in the cycle of flare-ups and setbacks.

A New Chapter: Isometric Loading

In 2019, Dr. Keith Baar’s team showed that injured tendons aren’t just “stuck with damage” — they can actually remodel and heal when loaded the right way. The key is isometric exercise.

Unlike typical strengthening, isometric loading involves holding a muscle contraction without movement. But not all isometrics are the same. Dr. Baar emphasizes a specific type that helps bypass a challenge called stress-shielding, where stronger tendon fibers absorb most of the load while weaker, injured fibers get left out. With the right protocol, even the weaker fibers can be stimulated to adapt and heal.

What the Protocol Looks Like

Dr. Baar’s lab identified a simple but effective approach:

• Exercise: 4 cycles of 30-second holds

• Effort level: Moderate pressure (~50% of max effort) is enough — you should feel tension in the tendon without straining.

• Rest: 2 minutes between holds

• Total time: About 10 minutes per session

• Frequency: Once or twice daily, with at least 6–8 hours between sessions

The recovery period is just as important as the loading itself. It gives tendon cells time to respond to the signals from exercise and begin remodeling tissue.

Practical Considerations

• Avoid “jerk”: Rapid, sharp movements don’t distribute load evenly through tendons and are a common cause of injury. Isometrics should be performed gradually, pressing smoothly into resistance.

• Pain guidelines: Mild discomfort (1–2 out of 10) can be acceptable, but sharp or stabbing pain should be avoided.

Nutrition Matters Too

Exercise alone isn’t enough—your body also needs the raw materials to rebuild. Dr. Baar’s team paired isometric loading with a collagen-rich supplement strategy:

• 30 g of gelatin (or high-quality collagen from animal pelts)

• 50~225 mg of Vitamin C

• Taken 30~60 minutes before exercise

Why? Because exercise boosts blood flow to your tendon, and if collagen-building nutrients are already in your bloodstream, your body can immediately put them to use. In fact, studies showed double the collagen synthesis markers when patients followed this protocol compared to exercise alone.

When Will You See Results?

Patients often ask: “How long before I feel better?” The answer depends on both the individual and the tendon involved, but research gives us a helpful timeline:

▶️ Immediate (same day): Some (but not all) people feel pain relief right after one isometric session.

📅 Short-Term (≤4 weeks): Noticeable improvement in pain and function often begins within the first month.

📈 Medium-Term (4–12 weeks): Consistent pain reduction and functional gains become more reliable. Progress is often measurable on tendon-specific tests.

🏗️ Long-Term (12–18 months): Structural healing (better tendon stiffness and collagen remodeling) shows up on imaging — lasting changes take months to years.

** You may start feeling relief within weeks, but true long-term healing only continues if you keep up with the isometric exercise. The good news is that after about 8 weeks, you can usually reduce the frequency to 2–3 sessions per week (total 30min maximum) while still supporting tendon remodeling and resilience.

Final Thoughts

Re-injury cycles don’t have to be your story. With the right blend of science-backed exercise, nutrition, and guidance, your tendons can rebuild strength and resilience.

So next time you’re itching to get back to your sport—whether it’s pickleball, running, or just being active with family—remember: smart loading and fueling can be the bridge between frustration and freedom.

📌 Next Step: See the Exercises in Action

Understanding the science is one thing — but knowing how to do the exercises correctly is just as important. To help with that, I’ve created:

• A detailed handout with step-by-step instructions, exercise categories, and programming guidance.

• A video demonstration showing exactly how to perform the isometric exercises safely and effectively.

👉 You can find both in my next blog post: Practical Guide to Isometric Exercises for Tendon Healing.

References

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Baar, K. (2017). Minimizing Injury and Maximizing Return to Play: Lessons from Engineered Ligaments. Sports Medicine (Auckland, N.z.), 47(Suppl 1), 5–11. https://doi.org/10.1007/s40279-017-0719-x

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Clifford, C., Challoumas, D., Paul, L., Syme, G., & Millar, N. L. (2020). Effectiveness of isometric exercise in the management of tendinopathy: A systematic review and meta-analysis of randomised trials. BMJ Open Sport — Exercise Medicine, 6(1), e000760. https://doi.org/10.1136/bmjsem-2020-000760

Cook, J. L., Rio, E., Purdam, C. R., & Docking, S. I. (2016). Revisiting the continuum model of tendon pathology: What is its merit in clinical practice and research? British Journal of Sports Medicine, 50(19), 1187–1191. https://doi.org/10.1136/bjsports-2015-095422

Gilmore, N. K., Klimek, P., Abrahamsson, E., & Baar, K. (2024). Effects of Different Loading Programs on Finger Strength in Rock Climbers. Sports Medicine - Open, 10(1), 125. https://doi.org/10.1186/s40798-024-00793-7

Paxton, J. Z., Hagerty, P., Andrick, J. J., & Baar, K. (2012). Optimizing an Intermittent Stretch Paradigm Using ERK1/2 Phosphorylation Results in Increased Collagen Synthesis in Engineered Ligaments. Tissue Engineering. Part A, 18(3–4), 277–284. https://doi.org/10.1089/ten.tea.2011.0336

Power, D., Haddad, F., Wallis, S., & Baar, K. (2023). Ramping Isometrics for Accelerated Return to Play following Hamstring Tendon Repair: A Case Study. 3. https://doi.org/10.54080/MOMV6327

Shaw, G., Lee-Barthel, A., Ross, M. L., Wang, B., & Baar, K. (2017). Vitamin C-enriched gelatin supplementation before intermittent activity augments collagen synthesis. The American Journal of Clinical Nutrition, 105(1), 136–143. https://doi.org/10.3945/ajcn.116.138594

Steffen, D., Mienaltowski, M. J., & Baar, K. (2022). Scleraxis and collagen I expression increase following pilot isometric loading experiments in a rodent model of patellar tendinopathy. Matrix Biology, 109, 34–48. https://doi.org/10.1016/j.matbio.2022.03.006

Tam, K. T., & Baar, K. (2025). Using load to improve tendon/ligament tissue engineering and develop novel treatments for tendinopathy. Matrix Biology, 135, 39–54. https://doi.org/10.1016/j.matbio.2024.12.001