Achilles tendinopathy is one of the most common overuse injuries affecting runners and athletes, although it can also develop in people whose occupations involve prolonged standing or walking.
It typically presents as localised pain either in the mid-portion of the Achilles tendon or where the tendon attaches to the heel bone (insertional Achilles tendinopathy).
Many people also experience stiffness after periods of inactivity, particularly during the first few steps in the morning or when standing after prolonged sitting. Symptoms often ease once the tendon has warmed up during activity but may return later that day or the following morning after loading.
Understanding Achilles Tendinopathy
The Achilles tendon plays an important role in walking, running and jumping by storing and releasing elastic energy.
Rather than simply being an inflamed tendon, Achilles tendinopathy is now understood as a load-capacity problem. This means the amount of load placed on the tendon has exceeded what it is currently capable of tolerating.
Although tendons respond positively to exercise, they adapt much more slowly than muscles due to their relatively low blood supply and slower metabolic activity.
While pain may settle within weeks, meaningful improvements in tendon strength and load tolerance occur over several months of progressive loading. This slower rate of adaptation explains why Achilles tendinopathy often requires patience and a gradual rehabilitation program.
What Causes Achilles Tendinopathy?
Several factors can lead to an imbalance between the load placed on the tendon and its current capacity.
Common examples include:
- A sudden increase in running distance or speed while training for an event.
- Inadequate recovery following a demanding game or race.
- Returning to previous training volumes after a period of reduced activity, such as a holiday or injury.
When these increases in load occur faster than the tendon can adapt, the tendon’s capacity is exceeded and symptoms can develop.
The Tendinopathy Continuum
Current research describes tendinopathy as occurring along a continuum consisting of three stages:
- Reactive tendinopathy
- Tendon dysrepair
- Degenerative tendinopathy
The continuum is dynamic, meaning tendons can move both forwards and backwards through these stages depending on how they are loaded and managed.
Early assessment and treatment during the reactive stage improve the likelihood of reversing these changes before they become more persistent, often resulting in a quicker and more straightforward recovery.
Why Rest Alone Doesn’t Fix Achilles Tendinopathy
Unlike muscle strains or ligament sprains, which often require a period of protection while damaged tissue heals, successful management of Achilles tendinopathy depends on restoring the tendon’s capacity to tolerate load.
Rest can be helpful in reducing pain in the short term by removing the aggravating activity. However, prolonged rest alone does not strengthen the tendon and may further reduce its capacity.
As a result, symptoms commonly return once previous activity levels are resumed.
Instead, rehabilitation focuses on identifying a level of loading that the tendon can tolerate while gradually rebuilding its strength.
The challenge is finding the appropriate amount of load. Too much can irritate the tendon, while too little provides insufficient stimulus for adaptation.
Research supports the use of a pain-monitoring approach, where mild discomfort during exercise may be acceptable provided symptoms settle within 24 hours and do not progressively worsen.
Importantly, a minor increase in pain during rehabilitation does not necessarily indicate further tendon damage. Instead, it often reflects the tendon being exposed to a level of load that it is adapting to, provided symptoms remain within acceptable limits and settle appropriately afterwards.
Managing Your Overall Load
Managing Achilles tendinopathy can be challenging because the tendon is loaded not only during exercise but also through everyday activities such as walking, climbing stairs and occupational tasks.
Rehabilitation therefore needs to consider an individual’s total daily load rather than focusing solely on sport.
A recreational marathon runner, for example, will require a different rehabilitation plan to someone who spends most of their working day on their feet.
During busy sporting seasons or periods of increased work demands, the goal may be to manage symptoms while maintaining function before progressing rehabilitation more aggressively when overall loading can be reduced.
Exercise and Rehabilitation
Exercise remains the cornerstone of treatment.
Depending on the stage and irritability of the tendon, rehabilitation may begin with low-load isometric exercises before progressing through loading through full joint movement and eventually plyometric exercises that prepare the tendon for running and jumping.
As the tendon becomes stronger, exercises and activity levels should continue to progress to avoid plateaus and ensure the tendon regains the capacity required for everyday activities and sport.
Why Assessment Matters
A thorough assessment is essential to confirm that Achilles tendinopathy is the source of symptoms, as other conditions including retrocalcaneal bursitis, calf muscle injuries, plantaris pathology and inflammatory conditions can produce similar pain around the back of the ankle.
Once the diagnosis is confirmed, treatment should focus on:
- Temporarily modifying aggravating activities.
- Implementing a progressive strengthening program.
- Tailoring rehabilitation to the individual’s symptoms, activity demands and lifestyle.
Maintaining overall fitness is also an important consideration, and alternative forms of exercise can often be incorporated while temporarily reducing activities that excessively load the tendon.
The Takeaway
Achilles tendinopathy is not simply a condition that improves with time.
While rest may temporarily reduce pain, long-term recovery relies on progressively improving the tendon’s ability to tolerate load.
Early assessment, appropriate load management and an individualised rehabilitation program provide the best opportunity for a successful return to activity while reducing the risk of ongoing symptoms.
References
Cook, J. L., & Purdam, C. R. (2009). Is tendon pathology a continuum? A pathology model to explain the clinical presentation of load-induced tendinopathy. British Journal of Sports Medicine, 43(6), 409–416. https://doi.org/10.1136/bjsm.2008.051193
Silbernagel, K. G., Thomeé, R., Eriksson, B. I., & Karlsson, J. (2007). Continued sports activity, using a pain-monitoring model, during rehabilitation in patients with Achilles tendinopathy: A randomized controlled study. The American Journal of Sports Medicine, 35(6), 897–906. https://doi.org/10.1177/0363546506298279
Malliaras, P., Barton, C. J., Reeves, N. D., & Langberg, H. (2013). Achilles and patellar tendinopathy loading programmes: A systematic review comparing clinical outcomes and identifying potential mechanisms for effectiveness. Sports Medicine, 43(4), 267–286. https://doi.org/10.1007/s40279-013-0019-z
Scott, A., Squier, K., Alfredson, H., Bahr, R., Cook, J. L., Coombes, B., de Vos, R. J., Fu, S. N., Grimaldi, A., Lewis, J. S., Maffulli, N., Magnusson, S. P., Malliaras, P., McAuliffe, S., Oei, E. H. G., Purdam, C. R., Rees, J. D., Rio, E. K., Gravare Silbernagel, K., Speed, C., … Zwerver, J. (2020). ICON 2019: International Scientific Tendinopathy Symposium Consensus: Clinical Terminology. British Journal of Sports Medicine, 54(5), 260–262. https://doi.org/10.1136/bjsports-2019-100885
