Achilles injuries in runners

Achilles issues seem to haunt most runners at one time or another. It may happen while peaking for a race, while trying to maintain some high mileage or seemingly for no reason at all. Most runners first response is to rest and wait for the pain to settle. Then a quick Google search will lead you to some calf raise exercises. Pain gone, you get back into running with a new optimism but sure enough about 2-3 weeks later, it’s back!

So why are Achilles issues so hard to shake?

The Achilles tendon has a breaking strain of around 3000kg, so why does a little running make it so angry? There are two main contributors to injury, and I refer to them as contributors rather than causes. Achilles issues are more commonly the result of multiple factors all combining to create the injury. The first main contributor is repetitive spikes in the rate of loading as the Achilles is stretching. This is often caused by a stiff ankle or sudden addition of hill sprints. The other contributor is an abnormal direction of loading with forces pulling obliquely on a linear tendon structure. This can happen with very worn/dead shoes, a loss of ankle eversion (outwards tilt) or a stiff hip affecting leg rotation.

The success of any rehab depends on whether you can identify the biggest contributor. Pick the wrong one and it will have little or no impact on your injury. This is often why Google’s answer for the “best Achilles exercises” seems to show a rapid improvement for some. But have no effect on others.

So how do you figure out your main contributor?

For a one-sided Achilles issue you’re almost always looking at a one-sided deficit or asymmetry. The most common primary cause of one-sided deficits is the loss of range in the ankle after an ankle sprain. After the joint is twisted it develops limited dorsiflexion (movement of toes towards shin) and eversion (movement of ankle tilting outwards). The effect of lost dorsiflexion is to cause an early heel lift during the running gait, leading to a spike in Achilles loading. With lost eversion there is often a subtle variation in the direction of loading of the Achilles, to which the structure of the tendon is less tolerant.

If both Achilles are involved, you’re usually looking for something that is deficient on both sides. Or training changes that can cause a rapid increase in Achilles loading. One of the most common causes of bilateral biomechanical overload is restricted hip extension (leg moving behind you). This causes the knee to bend early, lifting the heel and causing a spike in Achilles loading as well as increase total load during the gait cycle. Other causes of cumulative Achilles load include sudden increases in hill running or sprint work. As well as shoes that are well past their used by date.

So identifying the primary underlying cause is probably the most critical element of any rehab program for the Achilles. Once the cause has been identified, the approach to fixing it takes a little more consideration and depends on what strategies are available to offset or rectify the deficit.

Should you stop running while you rehab your Achilles?

HELL NO!!! The other major issue we see with Achilles rehab is the negative effect of rest. It often seems intuitive that if you have pain on running, you need to take a break. The downside is the Achilles tendon, like any connective tissue in the body, requires regular and consistent loading in order to maintain a healthy structure. If that loading is taken away, pain may be reduced but the underlying tendon injury and its cause (stiffness, weakness, etc) will only worsen. If you have an Achilles injury your best option is to run every day. Consistent manageable distances on flat ground at a steady comfortable pace. Use your symptoms as a guide. A little soreness is OK but if it’s very sore, getting worse each day or becoming sharp, reduce your distance and pace.

What else?

A strength program is another crucial part of the Achilles rehab. The focus of the program is not just on providing the Achilles with some loading to encourage healing. You need to improve the ability of other muscles in the leg to create drive and reduce the demand on the calf. The exact makeup of the program really depends on a combination of running technique, distance and terrain. As well as your individual biomechanical strengths and weaknesses. Avoid generic programs, particularly programs that are not specifically for running.

Last but not least we have your choice of footwear. You need to find the right footwear to match your running technique. As well as any movement restrictions around your ankles or hips as well as your preferred fit and feel. It’s not a matter of always going for a higher drop shoe or heel wedges to take the pressure off the Achilles or to go for more support. Base your decision around the wear and compression patterns of your previous shoes in addition to observations of your movement patterns. Get advice from a good running-specific health professional or running shoe shop.

There’s no predictable time frame for the recovery of an Achilles. Try to be patient but still motivated and only make small changes to your rehab every week or two as you may not see a response to a change in the first few days.

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Pete Colagiuri
Sports Physio with 17 years experience and a Level 2 Running Coach. Pete's clinical specialties are complex and chronic running injuries and lower limb biomechanics. Pete works with track, road and trail runners and coaches across the spectrum from recreational to elite.

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