Achilles Tendinopathy: Why It Happens and How to Recover
The Achilles is a unique tendon. It’s built to store and release energy during walking, running, and jumping. Because it constantly manages high loads, its tissue turns over slowly. This makes it prone to breakdown under stress and slower to recover than muscle tissue.
Achilles tendinopathy isn’t just inflammation—it’s a degenerative process. The tendon’s collagen fibers lose their healthy alignment and become disorganized. The tissue often becomes waterlogged, stiff, and less responsive to stress. This change occurs due to chronic overload, poor biomechanics, or underlying health factors.
The Role of Overuse and Load
Tendinopathy usually builds over time. Repeated strain without proper recovery leads to small microtraumas that the tendon can’t fully repair. On the other hand, tendon rupture is often the result of a sudden, forceful load—typically on a tendon that’s already been weakened.
Load Stimulates Repair—But It Has to Be the Right Kind
Tendons respond positively to mechanical loading. Research shows that all contraction types—concentric, eccentric, and isometric—can stimulate tendon adaptation, provided the load is sufficient. Heavier loads and longer time under tension are especially effective. Simply put: it’s not just what you do, but how you do it that matters.
Inflammation Isn’t Always the Enemy
Acute inflammation plays an essential role in healing. It increases blood flow and kickstarts collagen production. Suppressing this inflammation too early (e.g., with NSAIDs) can interfere with tendon recovery, especially beyond the first 24–48 hours post-injury.
Tendons Are Slow to Change—But They Do
Because tendons are metabolically slow, full remodeling after injury can take 6–12 months. That’s why consistent, progressive loading is key. Think of it as building tendon resilience over time—not looking for a quick fix.
Risk Factors Beyond Training
Your rehab should address more than just movement patterns. Factors like body composition, diet, and health history matter:
High BMI and adiposity are linked to tendon problems.
Diets high in cholesterol may reduce collagen quality.
Smoking negatively affects tendon structure.
Diabetes contributes to a stiffer, more brittle tendon.
Conditions like RA, gout, and dyslipidemia are also linked to tendinopathy.
Medications can also play a role:
Statins have been associated with Achilles tendon issues, often appearing around 10 months after starting and potentially leading to rupture.
Corticosteroids can reduce collagen synthesis and decrease tendon strength.
Fluoroquinolone antibiotics (like ciprofloxacin) are linked to tendon injuries, especially in older adults. These reactions can occur within just over a week of starting the medication.
Age and Tendon Health
As we age, our tendons lose water content and become less elastic. Collagen turnover slows, which means healing takes longer. After age 30, tendon rupture risk increases. But exercise can help offset these changes. In fact, studies show that heavy resistance training in older adults leads to measurable improvements in tendon structure and strength.
How Tendons Adapt Over Time
Tendons, like muscles and bones, respond to long-term loading. Studies show that:
Athletes have thicker, stronger tendons.
Sports involving one-sided loading (like tennis) result in thicker tendons on the dominant side.
Resistance training promotes tendon adaptation, while running alone may not.
Tangible structural changes can take 24+ weeks to show.
What About Eccentric vs Concentric vs Isometric?
Good news: the contraction type matters less than how much load you’re using and how you apply it. All types can be beneficial as long as the load is appropriate. Instead of focusing on movement type, prioritize heavy, slow, controlled exercise with progressive overload.
A Thoughtful, Individualized Rehab Approach
Effective rehab for Achilles tendinopathy isn’t one-size-fits-all. It needs to:
Address your unique deficits and history
Start with symptom management
Progress gradually, using load to build tendon resilience
General rehab tips include:
Use heavier weights with longer hold durations
Aim for high strain, not just high volume
Progress slowly to avoid reinjury
Final Thoughts
Achilles tendinopathy is complex. It involves tissue changes, systemic health factors, and load management. But tendons do respond to the right kind of load. Recovery may be slow, but it’s absolutely achievable.
If you're dealing with Achilles pain or just want to future-proof your body, I can help. Let’s build a plan backed by science and tailored to your life.
References:
Arampatzis, A., Karamanidis, K., Morey-Klapsing, G., De Monte, G., & Stafilidis, S. (2007). Mechanical properties of the triceps surae tendon and aponeurosis in relation to intensity of sport activity. Journal of Biomechanics, 40(9), 1946–1952. https://doi.org/10.1016/j.jbiomech.2006.09.005
Boushel, R., Langberg, H., Olesen, J., Nowak, M., Simonsen, L., Bulow, J., & Kjaer, M. (2000). Regional blood flow during exercise in humans measured by near-infrared spectroscopy and indocyanine green. Journal of Applied Physiology, 89(5), 1868–1878. https://doi.org/10.1152/jappl.2000.89.5.1868
Couppe, C., Kongsgaard, M., Aagaard, P., Hansen, P., Bojsen-Møller, J., Kjaer, M., & Magnusson, S. P. (2008). Habitual loading results in tendon hypertrophy and increased stiffness of the human patellar tendon. Journal of Applied Physiology, 105(3), 805–810. https://doi.org/10.1152/japplphysiol.90361.2008
de Jonge, S., van den Berg, C., de Vos, R. J., van der Heide, H. J., Weir, A., & Verhaar, J. A. (2015). The tendon structure returns to asymptomatic values in non-operatively treated Achilles tendinopathy but is not associated with symptoms: A prospective study. American Journal of Sports Medicine, 43(12), 2950–2958. https://doi.org/10.1177/0363546515608260
Eriksen, C. S., Bayer, M. L., Kristiansen, J., Schjerling, P., Kjaer, M., & Magnusson, S. P. (2019). Heavy resistance training changes the mechanical properties of human tendon in older adults: A randomized controlled trial. BMC Geriatrics, 19, 139. https://doi.org/10.1186/s12877-019-1165-4
Farup, J., Rahbek, S. K., Riis, S., Vendelbo, M. H., de Paoli, F., & Vissing, K. (2014). Influence of exercise contraction mode and protein supplementation on human skeletal muscle satellite cell content and muscle fiber growth. Journal of Applied Physiology, 117(8), 898–909. https://doi.org/10.1152/japplphysiol.00261.2014
Hansen, M., Couppe, C., Hansen, C. S., Skovgaard, D., Kovanen, V., Larsen, J. O., & Magnusson, S. P. (2003). Impact of loading history and aging on the tendon, muscle and skeletal system. Scandinavian Journal of Medicine & Science in Sports, 13(5), 311–323. https://doi.org/10.1034/j.1600-0838.2003.00310.x
Langberg, H., Skovgaard, D., Asp, S., & Kjaer, M. (1999). Time pattern of exercise-induced changes in type I collagen turnover after prolonged endurance exercise in humans. The American Journal of Physiology, 276(4), E818–E824. https://doi.org/10.1152/ajpendo.1999.276.4.E818
Magnusson, S. P., & Kjaer, M. (2003). Region-specific differences in Achilles tendon cross-sectional area in runners and non-runners. European Journal of Applied Physiology, 90, 549–553. https://doi.org/10.1007/s00421-003-0865-8
