Chronic Achilles Tendinopathy: A Prospective Randomized Study Comparing the Therapeutic Effect of Eccentric Training, the AirHeel Brace, and a Combination of Both

Chronic Achilles tendon pain, manifested as a localized painful thickening of the tendon, is relatively common among middle-aged recreational athletes.1-3,5,9,11,15,21 Gradual onset of pain in the Achilles tendon with structural changes in the midportion of the tendon (2-8 cm above the calcaneal insertion) is called tendinopathy and is generally considered to be a difficult condition to treat.2,10,11,22,24,28

Several studies have demonstrated that treatment by heavy-load eccentric calf muscle training leads to good clinical results, with decreased pain and full recovery to previous activity level.2,7,8,17,18,23,28-30 Therefore, this treatment strategy has to be considered the standard for the treatment of chronic tendinopathy of the Achilles tendon. However, our clinical experience with eccentric training has shown that some patients discontinue this treatment because of the experience of pain during exercise.

Conservative treatment options other than eccentric training for chronic Achilles tendon pain have previously been less encouraging.4 In one literature review, the authors stated that many common treatments such as rest, strength and flexibility exercises, anti-inflammatory agents, or corticosteroids do not alter the natural course of this disease.4 These inconclusive results are explained with the multifactorial origin of Achilles tendinopathy so that one single treatment appears insufficient. Very few prospective randomized controlled trials exist to assist in choosing the best evidence-based treatment.4

Chronic Achilles tendinopathy is often associated with paratendinitis.13,19,21,24 Local massage is regarded as an important technique to loosen adhesions in paratendinopathy and to remove metabolites and other waste products via the venous plexus of the paratenon, and might have a positive effect on the course of chronic Achilles tendinopathy.16

The AirHeel brace (Aircast, Vista, Calif) is specifically designed to treat Achilles tendinopathy. The manufacturer claims that the 2 interconnected air cells located under the heel and above the calcaneus apply pulsating compression with every step to help reduce swelling and discomfort, and enhance circulation by a local massage effect, but these effects have not been proven with scientific studies.

The purpose of this prospective randomized study was to evaluate 3 different treatment protocols for chronic midportion tendinopathy of the Achilles tendon: (1) eccentric training, (2) the AirHeel brace, and (3) a combination of eccentric training and the AirHeel brace.

Our first hypothesis was that the AirHeel brace improves symptoms of chronic noninsertional tendinopathy. The second hypothesis was that the combination of eccentric training with the AirHeel brace has a synergistic effect.

Table 1. Data on 100 Patients With Chronic Achilles Tendon Paina

Material And Methods

One hundred patients were included in the study and randomly assigned to one of the 3 different treatment groups (Table 1): group 1, eccentric training (37 patients); group 2, AirHeel brace (35 patients); and group 3, combination of the AirHeel brace and eccentric training (28 patients).

The patients were recruited by announcing the study in local newspapers. Randomization for assigning the subjects to a treatment group was achieved with selecting random numbers between 1 and 3 in Microsoft Excel (Microsoft Corp, Redmond,Wash).

All of these patients had been suffering from a gradually evolving painful condition in the Achilles tendon located at the midportion for at least 3 months. Most of the patients were recreational athletes involved in activities such as jogging or running (29%), walking (15%), or other sports activities (33%).

In all cases, the diagnosis was based on clinical examination performed by the same investigator (R.W.), showing a painful thickening of the Achilles tendon located at a level of 2 to 6 cm above the tendon insertion. In all tendons, the diagnosis was confirmed by ultrasonography, in which the tendon changes were described as a local thickening of the tendon, irregular tendon structure with hypoechoic areas, and irregular fiber orientation.

In all cases, the condition caused pain during tendon loading that limited the desired activity level. Most patients (87 of 100) had previously been advised to treat the problem by resting the affected leg. A majority of the symptomatic tendons had been treated with other treatment regimens (nonsteroidal anti-inflammatory drugs, 78; local cortisone injection, 3; physiotherapy, 45; or orthotic treatment, 23) without satisfactory effect on the Achilles tendon pain. Patients with previous surgery or tendon rupture were excluded from this study.

At the initial visit, a clinical examination with assessment of height, body weight, and assessment of local tenderness was performed in every patient. The amount of pain during rest and activity was evaluated by the patients on a 10-cm-long visual analog scale (VAS). On the VAS, the amount of pain is recorded from 0 to 10 cm, where no pain is recorded as 0 and severe pain is recorded as 10. The joggers registered the amount of pain during jogging, runners during running, and walkers during walking (ie, registration depended on the patient's type of activity). Function of the hindfoot region was assessed with the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot scale.14 Every patient completed the Short Form-36 (SF-36). Ultrasound examination was performed to evaluate thickening of the tendon in its midportion (2-6 cm above the insertion) and the presence of paratendinitis. The tendon diameter was evaluated on longitudinal cross-sections. Other findings such as hypoechogenic structures, nodules, etc were also noted. All patients with pain at the insertion of the tendon (insertional tendinitis) or Haglund deformity were excluded from the study.

Eccentric Training Model

All patients in this intervention group were instructed on how to perform the eccentric training by the same investigator (R.W.). They were given practice instruction and a written manual on how to progress. The correct execution of the exercises was confirmed after 6 weeks. The training protocol was adopted from previous studies.2 The patients were instructed to perform the eccentric exercises 3 times daily, 7 days per week, for 12 weeks. They were also advised to use stable shoes when performing the exercises.

In the beginning, the loading consisted of the body weight. From an upright body position and standing with the whole body weight on the forefoot, with the ankle joint in plantar flexion (Figure 1A), the calf muscles were loaded by lowering the heel (Figure 1B). Two types of exercises were used. The calf muscle was eccentrically loaded both with the knee straight (Figure 1C) and, to maximize the activation of the soleus muscle, with the knee slightly bent. The calf muscles were only loaded eccentrically; no following concentric contraction was performed, as the patients were instructed to use the noninjured leg and/or the arms to return to the starting position.

Figure 1. Eccentric training. From an upright body position and standing with the whole body weight on the forefoot, with the ankle joint in plantar flexion (A), the calf muscles were loaded by lowering the heel (B). Two types of exercises were used. The calf muscle was eccentrically loaded both with the knee straight (C) and, to maximize the activation of the soleus muscle, with the knee slightly bent.

Each of the 2 exercises included 3 sets of 15 repetitions. The patients were told that muscle soreness during the first 1 to 2 weeks of training was to be expected and that the exercises were potentially painful, but to stop if the pain became disabling. When the patients could perform the eccentric loading without experiencing any minor pain or discomfort, they were instructed to increase the load on the tendon by using a backpack increasingly loaded with weights to reach a higher level of training. Thus, the eccentric loading of the calf muscles was gradually increased.

During the 12-week training regimen, jogging, walking, and bicycling were allowed if it could be performed with only mild discomfort or pain.

AirHeel Treatment

The AirHeel is a specifically designed brace for the treatment of Achilles tendinopathy (Figure 2). Patients were instructed to wear the AirHeel during the daytime.

Figure 2. The AirHeel brace.


The evaluation of the efficacy of the treatment regimen was performed after 6 and 12 weeks of the intervention. At each follow-up, the outcome was assessed with the VAS for pain at rest, during gait, and during sports activities; the AOFAS hindfoot scale; the SF-36; and ultrasound examination. To avoid bias, the evaluation of the VAS and the SF-36 was done by the patient alone. All patients were questioned for possible adverse effects of the treatments (eg, tendon rupture, discomfort, severe pain).

For a 1-year follow-up, patients were asked to fill out the questionnaires for the AOFAS, report the pain on the VAS, and to report whether they reached their preinjury sports level.


The experimental protocol for this study was approved by the Ethical Committee of our University. All patients gave their consent to participate in this treatment model.

Statistical Evaluation

Commercial software (StatView 5.0, SAS Institute, Cary, NC) was used for all statistical calculations. A repeated-measures analysis (3 groups by 4 measurements) was performed. The results are expressed as mean

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