Achilles Tendonitis and Exercises

I have another one of my Injury and Exercise Reports for you, with it focusing on Achilles Tendonitis and Exercise.

Lets get to part 1 of the report:

Achilles Tendonitis and Exercise


Overview of Achilles Tendonitis

With the increasing number of individuals engaging in recreational and sporting activities, Achilles tendonitis has become one of the fastest rising musculoskeletal conditions among athletes and non-athletes, especially with those involved in running activities.

The incidence of Achilles Tendonitis has dramatically increased over the last 30 years. Along with its rise, knowledge about the real nature of and treatment options for Achilles tenoinitis has significantly progressed.

One of the most important discoveries is that the signs and symptoms of Achilles tendonitis are not exclusively caused by prostaglandins, the hormone-like substances that induce inflammation (Gottschlich et al, 2009). Interestingly, a landmark study found that its manifestations are mainly caused by degenerative changes in the Achilles tendon (Astrom & Rausing, 1995). Now that it is no longer strictly recognized as an inflammatory condition, the term Achilles tendonitis is replaced with Achilles tendinopathy or Achilles Tendonosis.

Today, experts and practitioners continuously explore and discover new information about Achilles tendinopathy to implement interventions that may effectively inhibit and alleviate its symptoms, which can be debilitating if left untreated. Simple exercises are effective preventive and protective interventions against this musculoskeletal condition. This will be further discussed in the Exercise section.

The Basics of Achilles Tendonitis

Achilles tendonitis was the term used to describe a spectrum of Achilles tendon injuries, ranging from signs of inflammation and tendon rupture to bone spur formation in the heel and swelling of the fluid-filled sac found at the back of the heel bone.

In 1995, a study published in Clinical Orthopaedics & Related Research indicated that degenerative changes, characterized by abnormal structure of tendon fibers, abnormal excess of cells and proliferation of blood vessels, were noted in 90% of biopsy specimens from symptomatic parts of the Achilles tendons of individuals with chronic Achilles tendonitis (Astron & Rausing, 1995).

Based on these findings, the pathology involving the Achilles tendon is grouped into three classifications: paratenonitis, tendinosis and paratenonitis with tendinosis.

  • Paratenonitis – It involves inflammation of the surrounding outer layer of the Achilles tendon, the paratenon, which nourishes the tendon. Partial or full tendon ruptures are usually the outcomes of end-stage paratenonitis.
  • Tendinosis – This degenerative condition of the Achilles tendon is usually caused by repetitive microtrauma or failed inappropriate healing response. When examined, the affected tendon does not demonstrate the presence of inflammatory cells.
  • Paratenonitis with tendinosis – This condition involves inflammation of the Achilles tendon with signs of degenerative changes. It is believed its occurrence is associated with disruption of blood flow (Buschbacher, Prahlow & Dave, 2009).

Basic Anatomy of Achilles Tendon


The term Achilles tendon is named after the most powerful and strongest warrior in Greek mythology’s Trojan War. In spite of Achilles’ incredible strength, he had one major weak spot, his heel.

The features and functions of Achilles tendon are quite similar to Achilles. The Achilles tendon is the largest, thickest and strongest tendon in the human body. It can efficiently absorb shock or the ground reactive forces associated with running, which can approach as much as eight times body weight with an average of 800 foot strikes per mile (Dubin, 2005).

Merging of the Gastrocnemius Muscle and Soleus Muscle

Achilles tendon runs from the top of the heel to the back of the calf. The calf is mainly composed of two muscles: the gastrocnemius muscle and soleus muscle. The tendinous portions of these muscles merge to form the Achilles tendon, which then attaches them to the heel bone. The gastrocnemius, the largest and most superficial of the calf muscles, is the main muscle force during running and walking. The soleus muscle is found underneath the gastrocnemius. Its supports the upright position when standing and increases the angle between the foot and the ankle.


Unique Features of the Achilles Tendon Sheath

Despite its toughness, the Achilles tendon has the ability to glide, which is mainly due to the structure of its surrounding sheath. In contrast to other tendons, the Achilles tendon does not have a true tendon sheath. Instead, it is surrounded by a thin paratenon, a double-layered sheath of synovial cells.

The outer layer of the paratenon is continuous with fat tissues. Its inner layer is continuous with epitenon, which is in direct contact with the Achilles tendon itself. The space between the epitenon and paratenon contains a lubricating fluid that allows gliding of the Achilles tendon when running or walking.

Collagen and the Achilles Tendon

Collagen is a group of fibrous proteins that help the Achilles tendon transmit forces and withstand pressure. Healthy Achilles tendons mainly consists of type I collagen, which is the more rigid collagen fiber type. When tendons start to degenerate for some reason, type I collagen fibers are replaced with type III collagen fibers, which are weaker than type I.

Blood supply to the Achilles Tendon

Compared with other tissues, the Achilles tendon has a limited blood supply, which is mainly derived from the blood vessels traversing the Mestinon, the layer found between the paratenon and epitenon. Blood supply is also obtained directly from the muscles to which the tendon runs through and distally from the bone where the tendon inserts into the heel bone.

Biomechanics of the Achilles Tendon

The main function of tendons is to connect muscles and bones. To be more specific, the Achilles tendon merges the gastrocnemius and soleus, and then attaches them to the heel bone. The entire gastrocnemius-soleus muculotendinous unit traverses the knee joint, ankle joint and the lower ankle joint.

The connection between the calf muscles and the heel bone has an essential function. The Achilles tendon acts as a buffer that absorbs enormous amount of tension and stress during running and walking.

To limit the damage, a healthy Achilles tendon efficiently distributes the load or force between the gastrocnemius and soleus muscles and the heel bone. To consistently and effectively function as a shock absorber, the Achilles tendon should maintain mechanical strength, flexibility and elasticity (Maffuli et al, 2004).

Research showed that healthy tendons can stretch to as much as 4% of their original length before they are damaged. Rupture is more likely if the pressure exceeds by 8%.

Thank you very much for reading part 1 of Achilles Tendonitis and Exercises.  I will be back with part 2 very soon.

Have a great day.

Rick Kaselj, MS


Here are some of the other Injury and Exercise Reports that I have done in the past:

Here are some other articles that may interest you relating to Achilles Tendinitis:

Here is a video related to Achilles Tendinitis:

Heel Drop Exercise