Achilles Tendonitis

Gem Figueroa explores Achilles tendinopathy research on Achilles tendon pain, tendon loading and eccentric exercise. Symptoms and recovery vary, and proposed blood-flow mechanisms and historical protocols do not establish guaranteed recovery or make every increase in pain harmless.

Why does the Achilles tendon matter in daily life?

The Achilles tendon plays a crucial role in our day to day lives and most people do not even realize it. Unfortunately, the tendon is very prone to injury. Being the largest and strongest tendon in the body, it attaches the calf muscles to the heel bones and stabilizes the feet during flexion and extension.

This means that we use it every day when walking, running, going up stairs, or even driving. The term “tendonitis” describes an inflammation of a tendon typically from overuse. The body usually adapts to everyday use of this important tendon.

However, certain athletes are exposed to movements that demand more from this tendon. A lack of awareness when doing Achilles-heavy movements may lead to a debilitating injury. The focus then shifts away from the injury itself and towards rehabilitation.

Achilles tendon pain in athletes

A 2015 study revealed that Achilles Tendonitis affects roughly 2% of the general population. But it affects 9-40% of individuals that play sports (the percentage varies depending on the sport being played). For non-athletes, the 2% is arguably not as significant as the 9-40% rate for athletes.

Such an injury may hinder their performance and, in turn, influence their success. It is important to learn the specific causes of such injuries to avoid time off and de-training.

How can loading relate to tendon symptoms?

When Achilles Tendonitis occurs, the fibers are damaged from excessive strain. Because this tendon connects the heel to the calf, athletes that are involved in sports with intense running (football, basketball, or tennis) are more prone to the injury, according to a 2015 study. The demands of a sport place higher volumes of stress on the tendon.

Over time, it becomes too much for the tendon to accommodate, causing the fiber tears. When the tendon is damaged, the body begins to repair it. This results in inflammation which is responsible for the pain.

Why can symptoms persist during daily activities?

Ideally, the body may be able to heal over time and the Achilles can return to normal. However, this ideal situation is often far from reality. Probably the first reaction of the athlete would be to take a break from the sport.

At the very least, stop the movement that caused the injury to give the tendon some rest. However, the Achilles is a tendon repeatedly used for simple movements such as walking or even getting up from a chair. Because such simple activity aggravates the tendon, the healing process is slowed or even stopped.

With Achilles Tendonitis, athletes typically fall into a lengthy cycle of continuously aggravating the injured tendon. They cannot help but use this tendon in their everyday lives outside of their sport. Unfortunately, the injury often becomes chronic and lasts for months.

What is known about blood flow and healing mechanisms?

To provide some background information, muscles and tendons get the nutrients to heal from blood supply. Blood supply is relevant to tissue function, but more visible vessels or circulation do not by themselves establish faster tendon healing. Unfortunately, tendons such as the Achilles do not receive a great deal of blood flow and, thus, heal slower than muscles when damaged.

“The Tendon of Achilles of individuals with tendinopathy presents a greater number of blood vessels when compared with healthy individuals” and “an interruption of flow during plantar flexion with normalization after rest. This process can be damaging to the vessels, especially considering that this process is repeated 180 times in the eccentric exercise program, which intensifies the number of vessels for repair” according to a 2016 study.

The study suggested that there are more blood vessels in the tendon because it is injured, but there is less blood flow. The vessel findings are part of proposed mechanisms; they do not establish that greater vessel numbers are always beneficial or that vessel congestion explains the healing timeline. Additionally, “when compared to eccentric training versus nocturnal orthosis associated with eccentric training, blood flow reduction was greater in the eccentric training group”.

The cited 2015 clinical commentary reviews several proposed mechanisms of eccentric exercise and states that the mechanism of benefit is not fully understood. Thus, eccentric exercises are not magic, although the whole process may seem very magical.

What does eccentric exercise research discuss?

A 2015 clinical commentary discussed eccentric calf raises as a treatment approach for Achilles tendinopathy. The therapeutic exercise consists of a slow “lowering” portion of a calf raise. When lowering from a calf raise, the calf muscles are put under load along with the Achilles tendon.

Initially, the athlete performing this may not feel any improvement or may even feel the pain worsen.

Pain response varies; an increase in pain should not automatically be considered harmless or certain to subside. The historical eccentric protocol discussed uses 3 sets of 15 repetitions twice daily over 12 weeks or more; this is a description of a studied approach, not one compulsory schedule for every person. “In recent years researchers have attempted to determine the clinical effectiveness of eccentric exercises, most authors reported successfully returning 60% of participants back to sport, which contrasts with the 100% reported to have returned to sport in Alfredson’s original paper. The lower success rates observed in later trials is thought to be due to a poorer response to isolated eccentric exercises in non‐athletic and female individuals when compared with athletic subjects”.

The quoted studies report differing return-to-sport results, so they do not establish guaranteed recovery for every athlete.

The 2024 clinical practice guideline recommends tendon-loading exercise as first-line care for midportion Achilles tendinopathy when tendon frailty is not suspected. It also advises against complete rest for that population, with activities kept within pain tolerance. These recommendations are specific to midportion tendinopathy; they do not make the historical eccentric schedule a universal plan for every Achilles injury.

How should recovery claims be interpreted?

Achilles Tendonitis is an injury that can happen to anybody, but more frequently in athletes. Thus, it is important to know the appropriate steps to take next to get back to playing again. The Achilles tendon is the largest and strongest tendon in the body.

Eccentric exercises are one researched approach, but the “secret” is not a demonstrated blood-flow formula guaranteeing complete recovery. It is a much more important tendon than people may think. Consider giving it some appreciation for being both the strongest and weakest part of you.

References

O’Neill, S., Watson, P. J., & Barry, S. (2015). WHY ARE ECCENTRIC EXERCISES EFFECTIVE FOR ACHILLES TENDINOPATHY?. International journal of sports physical therapy, 10(4), 552–562.

Rabusin, C. L., Menz, H. B., McClelland, J. A., Evans, A. M., Landorf, K. B., Malliaras, P., Docking, S. I., & Munteanu, S. E. (2019). Efficacy of heel lifts versus calf muscle eccentric exercise for mid-portion Achilles tendinopathy (the HEALTHY trial): study protocol for a randomized trial. Journal of foot and ankle research, 12, 20. https://doi.org/10.1186/s13047-019-0325-2

Souza, R. V. de, & Araújo, V. L. (2016). The effect of eccentric training on tissue repair in individuals with Achilles tendinopathy: a literature review. Manual Therapy, Posturology & Rehabilitation Journal, 1–8. https://doi.org/10.17784/mtprehabjournal.2016.14.378

Reid, H., & Wood, S. (2015) Achilles Tendinopathy: Advice and Management Information for Patients

Chimenti, R. L., Neville, C., Houck, J., Cuddeford, T., Carreira, D., & Martin, R. L. (2024). Achilles Pain, Stiffness, and Muscle Power Deficits: Midportion Achilles Tendinopathy Revision – 2024. Journal of Orthopaedic & Sports Physical Therapy, 54(12), CPG1–CPG32. https://pubmed.ncbi.nlm.nih.gov/39611662/

Pull Quotes:

“A lack of awareness when doing Achilles-heavy movements may lead to a debilitating injury.”

“A 2015 clinical commentary discussed eccentric calf raises as a treatment approach for Achilles tendinopathy.”

“Achilles Tendonitis is an injury that can happen to anybody, but more frequently in athletes.”