Achilles Tendon Pain: From Irritation to a Resilient Tendon

What lies behind it

The calcaneal tendon, commonly referred to in everyday language as the Achilles tendon, is the thickest and strongest tendon in the human body. It connects the three-headed calf muscle, the triceps surae muscle, with the calcaneal tuberosity, the tuber calcanei. With every single step, this connective tissue structure transmits several times the body's weight onto the lever of the forefoot. To withstand these immense tensile forces, the tendon is composed of densely bundled collagen fibres that ensure high tensile strength while simultaneously providing elastic energy storage.

However, the blood supply to the Achilles tendon is anatomically limited. A hypovascular zone exists particularly in the region two to six centimetres above the calcaneal insertion. Microcirculation is reduced in this area, which slows down the body's repair mechanisms following heavy exertion. If repeated microtrauma causes more minor tissue damage than the body can repair during rest phases, the tendon enters a state of chronic failed healing.

In modern sports medicine and orthopaedics, this condition is no longer classified as a classic inflammation, but as a tendinopathy. Histological examinations show that hardly any classic inflammatory cells are present in the tissue during a tendinopathy. Instead, a disorganisation of the collagenous architecture occurs. The tight, parallel aligned type I collagen is gradually replaced by type III collagen, which has lower tensile strength. In addition, increased amounts of proteoglycans accumulate in the tendon matrix, binding water and leading to a visible, fusiform thickening of the tendon body.

If affected individuals remain in this phase without therapeutic intervention, the body responds by sprouting small, inferior blood vessels from the paratenon. This neovascularisation is regularly accompanied by the ingrowth of fine, pain-sensitive nerve fibres. Consequently, the typical pain symptoms do not stem from an acute inflammatory reaction, but from the interaction of mechanical instability, altered tissue tension, and the irritation of these ingrown nerve structures.

Typical signs

The clinical presentation of Achilles tendinopathy manifests as a characteristic sequence of symptoms. The most defining symptom of the primary phase is start-up pain, often experienced as morning stiffness. Patients regularly report significant limitations immediately upon waking or after prolonged periods of sitting. The tendon feels stiff and immobile. After a few minutes of moderate walking, the sensation of pain temporarily subsides because blood flow to the paratendinous tissue increases and mechanical friction within the tissue decreases.

As structural changes in the tendon progress, this pattern changes. Pain no longer occurs only at the onset of exertion, but accompanies every physical activity and persists as lingering pain at rest or post-exertional pain. Local tenderness to palpation is easily triggered along the tendon strand. The tissue often feels doughy or nodularly thickened. When moving the ankle joint, a fine creaking or rubbing may be felt, which is medically assessed as crepitus.

Precise differentiation of pain localisation and distinction from other conditions in the hindfoot region are of central importance for targeted treatment:

• Mid-portion tendinopathy: Symptoms and tissue thickening manifest two to six centimetres above the calcaneal insertion in the hypovascular zone of the tendon.
• Insertional tendinopathy: The point of pain lies directly at the bony junction with the calcaneus, often in combination with traction exostoses or spur formation.
• Retrocalcaneal bursitis (bursitis subachillea): Inflammation of the bursa between the anterior surface of the Achilles tendon and the calcaneal tuberosity, often triggered by direct pressure from shoe edges.
• Haglund's deformity: A bony prominence on the superior posterior border of the calcaneus, leading to chronic friction trauma of the soft tissue.
• Plantar fasciitis: Pain on the sole of the foot near the anterior edge of the heel, which is often mistakenly confused with tendon complaints.

Everyday causes

The development of tendon complaints in the hindfoot is rarely based on a single trigger. In most cases, reduced tissue load capacity coincides with a combination of mechanical overload factors in daily life. The footwear worn plays a dominant role in this context. Shoes with an extremely hard, inflexible, or ill-fitting heel counter exert continuous pressure on the tendon insertion during every roll-over phase. When the upper edge of the heel counter presses horizontally into the tendon body, shear and compression forces arise that exacerbate the reduction of microcirculation in the tissue.

A sudden change in shoe drop is equally critical. The drop refers to the difference in sole height between the heel and the forefoot. Switching abruptly from shoes with a high drop to flat minimal shoes or barefoot shoes exposes the calf muscles and the Achilles tendon to a suddenly increased tensile strain. If the muscle-tendon unit lacks time for adaptive lengthening, the connective tissue responds with micro-tears.

Anatomical aspects and axial misalignments of the foot reinforce this effect. Pronounced hyperpronation, in which the calcaneus collapses excessively inwards upon heel strike, subjects the Achilles tendon to asymmetric tension. The tendon is not subjected to purely axial loading, but is twisted over an edge. This torsional stress leads to unequal tension distribution within the collagen fibre bundles. A pronounced pes cavus, on the other hand, exhibits reduced shock-absorbing flexibility, causing impact loads to be transmitted undampened into the heel tendon.

Systemic influences must not be overlooked during cause analysis. Elevated blood glucose levels in diabetes mellitus lead to advanced glycation of tissue proteins. These so-called advanced glycation end products cross-link collagen fibres unnaturally, which drastically reduces the tendon's elasticity. Obesity, lipid metabolic disorders, or the use of certain medications such as fluoroquinolone antibiotics also significantly impair tendon health.

When medical evaluation is necessary

A large proportion of functional tendon irritations can be positively influenced by conservative measures and podiatric care. Nevertheless, there are medical red flags that require immediate evaluation by a specialist in orthopaedics or trauma surgery. If a sudden, whip-crack pain occurs in the lower leg during exertion, accompanied by an audible snapping sound, an Achilles tendon rupture is urgently suspected.

In the event of a complete tendon tear, the affected person loses the ability to press the foot downwards against resistance or to stand on tiptoe. During palpation, a distinct gap along the course of the tendon is often palpable. In this situation, ultrasound or magnetic resonance imaging diagnostics must be initiated immediately to weigh the need for surgical or specific conservative immobilisation measures.

If pronounced redness, noticeable local overheating, and widespread swelling develop in the heel region, an infectious bursitis or bacterial tissue inflammation must be ruled out. Severe pain at rest and during the night, which persists independently of mechanical load, also requires a differentiated medical diagnosis. Rheumatological systemic diseases such as spondyloarthritis or bone derangements must be excluded here before purely functional therapies are continued.

What podiatric treatment can achieve

Podiatry plays an important role in the management of Achilles tendon complaints at the intersection of skin care, pressure relief, and functional movement analysis. At the core is the recognition that secondary changes to the skin of the foot can exacerbate pain conditions in deep tissue. If patients adopt a compensatory gait due to tendon discomfort, the roll-over mechanics of the foot change significantly. This results in massive callus formation, pressure points, or painful skin fissures in the heel area.

Targeted /en/services in the form of podologische Komplexbehandlung (comprehensive podiatric treatment) focus on the professional removal of excessive callosities. Hyperkeratoses in the heel region reduce the physical elasticity of the skin envelope. With every step, high tensile stresses build up under the hard callus layer, generating referred pain stimuli. Through the precise use of scalpel-based techniques and rotary instruments, the elastic balance of the skin surface is restored, which facilitates the roll-over movement.

A major podiatric focus lies in the fabrication of custom pressure and friction protection devices. Using medical silicone compounds, custom-made orthoses are fitted that protect sensitive tendon areas from the hard heel counter of the shoe. These devices redistribute the occurring forces to surrounding, resilient tissue areas and prevent localized compression of the damaged tendon or bursa.

In addition, a thorough examination of the worn footwear is conducted to inspect wear patterns and mechanical weaknesses. The stability of the heel counter, the flexibility of the outsole, and the internal volume of the shoe are professionally assessed. In our practice, Helga Maria Freitag performs an independent assessment of the foot as a /en/sectoral-practitioner for podiatry (sektorale Heilpraktikerin für Podologie). This allows abnormal mechanical loading to be precisely analysed and podiatric interventions to be optimally tailored to individual anatomical conditions. In addition, targeted local application of cold can be used to alleviate painful swelling in paratendinous tissue. Detailed information on this treatment approach can be found under /en/cryotherapy. Regular treatment intervals of four to six weeks sustainably support the recovery process.

What you can do yourself

Restoring the structural load capacity of a degraded Achilles tendon requires active participation from the affected individual. The tissue responds to mechanical stimuli, but requires time to synthesise new collagen fibres due to its slow metabolic rate. Pure rest or remaining in prolonged inactivity is demonstrably counterproductive, as organized tissue regeneration cannot occur without mechanical loading stimuli.

The key to improvement lies in pain-adapted, progressive strength training of the calf muscles. Isometric exercises have proven effective in the early phase of tendon irritation. Here, tension is maintained in the calf muscles without movement occurring in the ankle joint. This form of loading activates the neurological pain-inhibition system and maintains muscular motor control.

As soon as acute pain subsides, eccentric heel raises form the foundation of home exercise. This exercise is performed in a step-by-step, structured manner:

1. Assume the starting position: Stand with the forefeet of both feet on the edge of a stable stair step. The heels extend freely out over the edge. Hold onto a handrail.
2. Two-legged raise: Push yourself up onto tiptoes in a controlled manner using the strength of both legs, so as not to overload the affected tendon during the lifting phase.
3. Single-leg lower: Shift your entire body weight onto the affected leg. Lower the heel slowly and under control over a period of three to four seconds below the level of the step edge.
4. Return to starting position: Place the non-affected foot back onto the step and push up again using both legs, relieving the affected tendon during the ascending phase.
5. Follow the repetition schedule: Perform this movement three times daily with 15 repetitions per set. The training should be completed daily over a period of at least twelve weeks.

In addition, gentle self-massage of shortened calf muscle bellies using a hard foam roller is recommended. Applying local pressure to the gastrocnemius and soleus muscles reduces resting muscle tone, noticeably decreasing the persistent baseline traction on the Achilles tendon. Direct, firm pressure from the roller onto the thickened tendon itself should, however, be avoided.

Common mistakes

In podiatric practice, recurring mistakes regularly appear in the management of tendon complaints that delay healing or worsen the condition. The most widespread misconception is the assumption that strict bed rest or wearing immobilisation boots for weeks without medical indication heals the tendon. Lacking mechanical tensile stimuli, the body degrades tendon mass. Newly formed collagen is laid down in a disordered fashion, making the tendon even more susceptible to recurrent microtrauma after the period of rest ends.

Another serious mistake is excessive stretching of the calf muscles during the acute pain phase, particularly in insertional tendinopathy. If the heel is lowered deeply when irritation exists at the bony insertion, the tendon compresses under extreme pressure against the calcaneal tuberosity. This mechanical compression further squashes the irritated tissue and the underlying bursa. Stretching exercises for insertional complaints should therefore only be performed up to the neutral position of the foot.

Equally critical is the uncontrolled long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or diclofenac. While these medications alleviate pain in the short term, they simultaneously inhibit tenocyte activity. These tendon cells are strictly necessary to build new collagen matrix. Due to pharmacological pain relief, affected individuals also tend to overload the tendon prematurely in daily activities.

Finally, persisting with worn-out footwear regularly leads to relapses. When the heel counter is stretched out from worn-down heels, the hindfoot loses its lateral guidance. The resulting eversion movement of the calcaneus generates harmful shear forces in the tendon with every step. Timely replacement of everyday shoes is a simple yet effective preventive measure.

Current evidence and context

Scientific research into tendon pathologies has led to a fundamental paradigm shift in recent decades. While inflammatory processes were assumed in the past and immobility was prescribed, modern biomechanical studies demonstrate the necessity of controlled tensile loading [1]. The protocol developed by Alfredson for eccentric calf training already showed excellent clinical results in chronic mid-portion tendinopathies in the late 1990s [2].

In more recent comparative studies, heavy slow resistance training is increasingly evaluated. This form of slowly performed, heavy strength training demonstrates higher patient compliance than eccentric programs performed multiple times daily, while achieving equal clinical success in terms of pain reduction and tendon structure [3]. Through the combination of concentric and eccentric phases under heavy loads, the new synthesis of type I collagen in tenocytes is maximally stimulated.

The continuum model of tendinopathy according to Cook and Purdam categorises tendon changes into three phases: reactive tendinopathy, tendon disrepair, and degenerative tendinopathy [4]. While load reduction and avoiding compression are the primary focus in the reactive phase, advanced stages require progressive mechanical stimuli to restructure the matrix. Systematic reviews also emphasise that passive measures such as orthotic insoles, bandages, or physical therapies offer valuable synergies, but can never fully replace active exercise therapy [5].

Treatment in Memmingen

At the premises of FREITAG® Podologie GmbH at Kempterstr. 25 in Memmingen, we place great importance on sound management of foot and tendon problems. Our catchment area extends across the entire Unterallgäu as well as the neighbouring regions of Allgäu and Upper Swabia. We analyse your foot statics, evaluate pressure distribution in the shoe, and provide you with tailored pressure-relief elements.

Whether preventive measures, professional removal of bothersome calluses, or the fabrication of custom orthoses to relieve heel counter pressure: our goal is the sustainable restoration of your freedom from pain. For a thorough evaluation of your foot health or to make an appointment, please feel free to get in /en/contact with our practice.