Achilles tendon pain? Here's how to recognise this injury

The Achilles tendon is your body's strongest tendon. It connects your calf muscles to your heel bone and, when running, it receives forces of up to six to eight times your body weight. This is not a problem, as long as the tendon is sufficiently resilient and there is sufficient recovery time between efforts. 

In Achilles tendinopathy, there is usually no classical inflammation. The problem lies in a disrupted repair process of the tendon tissue. Repeated strain causes small micro-damages. Normally, the body can recover from this well and and the tendon even gets stronger. But when the load increases faster than the recovery rate, the structure of the collagen becomes disrupted. The fibres become less well ordered, the tissue becomes stiffer and more sensitive, and sometimes a slight thickening develops.

We roughly distinguish two forms¹: complaints in the middle part of the tendon (midportion tendinopathy) and complaints at the attachment to the heel bone (insertional tendinopathy). This distinction is relevant because certain exercises or deep stretches can actually cause additional irritation in insertional complaints.

In practice, we rarely see a clear cause. It is usually a sum of factors that combine to make the tendon take on more than it can handle.

The most common factor is building up load too quickly. Think of a new running schedule, longer walks or a sudden increase in intensity. Tendons adapt less quickly than muscle tissue. Whereas muscle strength can improve within weeks, tendon tissue takes months to become structurally stronger. Prospective research in runners shows that changes in training load and biomechanical factors play a clear role in the development of complaints².

In addition, subtle changes in movement patterns can have an impact. A different shoe, more forefoot landing, more of a hill training, these are small adjustments that can have big effects on the pull in the tendon. By the way, this does not mean that you are moving “wrong”, but rather that your tendon needs time to adapt to a new stimulus.

Reduced strength in the calf muscles also often plays a role. The calf muscles and the Achilles tendon function as a system. When the muscle is insufficiently strong or quickly fatigued, relatively more strain falls on the tendon. Targeted strength training is therefore an essential part of recovery³.

Finally, recovery capacity is an underestimated factor. Sleep deprivation, stress and not enough rest days can cause the body to recover less well from strain. Tendon tissue is more sensitive in this than many people think.

Achilles tendon complaints often follow a fairly typical course. At first, there is mainly stiffness. Especially in the morning or after a period of sitting, the ankle feels stiff. After a few minutes of exercise, it seems to improve. This gives a false sense of security.

Later, you see that the pain returns during or after strain. Sometimes not until hours later. Pressure on the tendon may be sensitive and slight thickening may occur. The characteristic feature is that the symptoms are variable, good days alternating with lesser days.

It is important to understand that pain does not automatically mean permanent damage. But it does signal that the relationship between load and load capacity has become unbalanced.

Completely stopping exercise seems logical with these symptoms. Yet in Achilles tendinopathy, that is rarely the best solution. Tendons react badly to prolonged inactivity. The load capacity then actually decreases further, causing the symptoms to return faster as soon as you start your sporting activities again.

Research shows that targeted exercise therapy is more effective than rest alone³. So the goal is never to completely zero strain, but it's in the right dosage. You want to stimulate the tendon enough to provoke adaptation without overloading it again.

The first step is to adjust your load. This does not mean stopping, but temporarily exercising less intensively or for less time. A practical guideline is that mild to moderate pain during exercise (e.g. maximum 3 out of 10) may be acceptable, as long as the symptoms do not worsen the next day. Explosive load such as sprinting, jumping or intensive hill training is best avoided temporarily in this phase.

The second pillar is progressive calf strength training. Eccentric training where you lower slowly and in a controlled manner have been extensively researched and shown to be effective in midportion Achilles tendinopathy³. We now know that it is less about being “eccentric” and more about the principle of progressive loading. The tendon must be gradually loaded more heavily to become stronger.

Above all, this means starting slowly, executing well technically and building up in resistance step by step. Don't force it, but don't underload it either.

The third pillar is patience. Tendon repair is slower than muscle repair. On average, think about eight to 12 weeks before clear improvement occurs, sometimes longer depending on how long the symptoms have existed. Recovery is rarely linear. Fluctuations are part of it. As long as the general trend is upward, you are on the right track.

When Achilles tendon problems persist for a longer period of time or do not improve sufficiently with exercise therapy alone, additional diagnostics or treatment may be useful. At Physio Fitaal Tilburg we look not only at the pain, but at the underlying repair ability of the tendon. Thereby, ultrasound, shockwave therapy and EPTE (Percutaneous Electrolysis Therapy) can be a valuable addition to an overall plan and is never used as a single, quick fix.

With ultrasound we visualise the structure of the Achilles tendon. We can see whether there is thickening, changes in the fibre structure or irritation at the attachment to the heel bone. This helps to distinguish between midportion and insertion complaints and to determine more specifically which load and exercise form is appropriate. Important to know: what is visible on ultrasound does not automatically explain the pain. Structural changes also occur without complaints. So we use the ultrasound as an aid to more targeted treatment, not as a goal in itself.

For more long-term or persistent complaints, shockwave therapy are employed. Here, targeted sound waves are delivered to the affected tendon area to stimulate the local repair process and influence pain sensitivity. Shockwave is particularly used for chronic Achilles tendon problems or insertional problems at the heel bone. It does not replace exercise therapy, but in combination with progressive strength training can support the recovery process.

Another additional option is EPTE (Percutaneous Electrolysis Therapy). This involves placing a thin needle in the affected tendon area under ultrasound guidance, after which a light electric current triggers a targeted repair response. The advantage of EPTE is that it works very locally, without putting unnecessary strain on surrounding tissue. We mainly use this technique in cases of long-term tendinopathy or when clear degenerative zones are visible that do not respond adequately to regular exercise therapy. Again, EPTE never stands alone, but is always combined with a carefully constructed exercise programme to structurally improve load capacity.

Which approach is appropriate depends on the duration of your symptoms, the location of the pain (midportion or insertion), your sport level and your goals. In many cases, targeted strength training is sufficient. But when symptoms keep recurring or do not recover sufficiently, a combination of exercise therapy with ultrasound, shockwave or EPTE can make all the difference.

So don't stay too long with persistent Achilles tendon pain. Do you live in Tilburg or the surrounding area and want to know which treatment suits your situation? At Physio Fitaal Tilburg we help you with a reasoned approach so that you can move strong, loadable and confident again.