In this post I take a look at Achilles injury.  Achilles injuries are common and up to 57% of runners will experience it at some stage. It is most commonly experienced as pain in the middle of the Achilles tendon during or after sport. This is called mid portion tendinopathy. Depending on the severity it can be sore to walk, and can be tender to pinch the tendon at the point of injury. Some shoes which press on the are can be uncomfortable. If you have had long standing tendon pain you may also feel a thickness in the area.
If the tendon is sore where it inserts into the heel is called insertional tendinopathy. This is less common.


 Frustrating Achilles injuries…

Achilles injuries can be frustrating ones, so lets get some on the more annoying aspects out of the way first:

  • Rest alone will not help. You could take a few weeks of rest and still feel the same pain when you go to run. If you feel a bump over the area it suggests that you have had it a while and continued to exercise on it, or you have had it previously.
  • It takes at least 12 weeks, and more likely 6 months to improve with rehab. Some acute injuries will resolve faster, longer standing issues can take longer to resolve, particularly if you keep irritating it.
  • You need to modify your exercise to levels where there is only some mild discomfort. In reality, a lot of sporting folk will try to continue their existing level of exercise. But the reality is you are just continuing to aggravate it and put the problem on the long finger. This can be very frustrating but continuing to exercise through pain just lengthens the period you have it. We need to tip the scales in favour of the rate of repair, rather than the rate of wear on the tendon.
  • You need to do your rehab.

Why did it happen?

One of the key factors that contributes to development of an Achilles issue is weakness in the calfs. In research studies it has been shown that those with Achilles tendinopathy have a more pronounced loss of Soleus (one of the calf muscles) force generating capacity compared to those without. Interestingly this is seen in both the injured and uninjured side when compared to a non-injured athlete.

The tendon helps to transfer force between the muscles and the joint they act on. When a muscle weakens it loses it’s ability to shock absorb and to control the amount of load being put through the tendon. This leads to more strain through the tendon and the development of tendinopathy.

When you run at a pace of approx. 12km/hr, a force of 1.2-1.8 times body weight can go through the Soleus, so it need to be very strong. In practice this means it needs to be strong enough for a 70kg runner to wearing a backpack with 14-35kg on their back and have enough calf strength to perform 4 sets of 15 reps of single leg calf raises.

At faster speeds and hill sessions the demands on the calf muscles are higher (2 – 2.5 times body weight).

Why is the problem on one side only?

For most people the problem is on one Achilles only and one of the questions we try to answer in the clinic is; why did it occur on this side? In sport the ankle is just one part of the kinetic chain. When an injury occurs at the ankle/Achilles we also need to look the other parts of the leg, such as the hip, knee and the core to determine if an issue here led to a change in load at the foot and subsequently the development of an Achilles problem.  Rehab for an Achilles issue will need exercises specific for the Achilles, as well as other exercises to target any other imbalances found further up the leg.

Orthotics: sometimes a heel raise worn in a shoe can reduce the discomfort in an acute Achilles as it shortens the tendon reducing the stress on it. This can be helpful to bring the discomfort down to manageable levels so rehab can start.

Some people like to try an orthotic to correct rolling inwards of the foot (over-pronation) which is helpful for some with Achilles. We find that strengthening muscular weakness at the hip and core can reduce over-pronation, but also take client preferences into account. We wrote a blog on how weak gluteals and core affect the knee and ankle (pronation) check it out here

What is happening at the Achilles tendon?

The Achilles tendon is made up of tendons from each of the calf muscles. It twists, which helps with some rotational movement of the ankle. However this twist is thought to lead to some internal stress on the midportion 2-6cm above the heel bone where the pain is frequently reported. If the rate of wear is greater than the rate of repair, tendinopathy develops. Tendons are structurally very different from muscles and hence this leads to a longer healing time.

Pain at the site of the tendon changes the way the muscles in the calf and shin work. Over time it can lead to weakness in these muscles but it also leads to reduced corticopspinal control which, in simple terms, is the brain  recruiting and activating the muscle fibres at the right time and to the right extent during exercise. Rehab needs to both strengthen the calf and incorporate exercises to improve corticospinal control.

It has been proposed that tendon injury can be of two types: 1. A reactive tendon. It is the first time tendon pain occurs and is due to an acute overload of the tendon e.g. tendon pain that occurs after a new gym class, or a hill repeat session. Once caught quickly and the younger you are, the more likely that appropriate rehab returns you to a normal tendon. 2. The degenerative tendon. This is not the first episode of tendon pain, or you have trained through tendon pain for a sustained periods, then the more likely you have a degenerative tendinopathy. There is a degenerative portion  within the tendon which is structurally unable to transmit the load leading to overload in normal parts of the tendon. Rehab is about trying to reduce overload in the normal parts of the tendon so it can help you continue sport with the degenerative portion still there.

Achilles tendinopathy research is big area of interest at present. It is not yet fully understand what happens at a cellular level to cause tendinopathy. Greater understandings of this will help lead us to better prevention and rehab strategies in the future.

What do we know that helps?

Much of the research has focused on using eccentric (lowering the heel to the floor) and concentric  (raising the heel off the floor) exercises to target the tendon and the calf. Many studies find that it can be helpful when sufficient load is added to the exercise over a number of weeks to make the tendon sufficiently strong to withstand the sporting activity you are involved in. Loan is gradually added as the pain in the Achilles reduces, and as strength improves.

Anything else?

High cholesterol and high levels viseral fat (fat around the organs or belly fat) which excrete pro-inflammatory markers has been linked to Achilles tendinopathy. Obesity and diabetes are also risk factors. Visit with your GP to have these areas checked if you have tendinopathy and are concerned that cholesterol may be contributing to it.


Further reading

If you are interested in reading more about some of the information referenced in this blog check out research by:

  • Cook JL, Rio E, Purdam CR, Docking SI. 2016.  Revisiting the continuum model of tendon pathology; what is its merit in clinical practice and research. British Journal of Sports Medicine 16;0:1-7 doi:10.1136/bjsports-2015-095422
  • Dorn T, Schache A, Pandy M. 2012. Muscular strategy shift in human running: dependence of running speed on hip and ankle muscle performance. Journal of Experimental Biology 215,1944-1956
  • Hohmann E, Reaburn P, Tetsworth K, Imhoff A. 2016. Plantar pressures during long distance running: an investigation of 10 marathon runners. Journal of Sports Science and Medicine 15 254-262
  • Henrisksen M, Aaboe J, Graven-Nielsen T et al. 2011 Motor responses to experimental Achilles pain. British Journal of Sports Medicine 45, 393-398 doi:10.1136/bjsm.2010.072561
  • Malliaras P, Barton CJ, Reeves N, Langberg H. 2013.Achilles and Patellar Tendinopathy Loading Programmes. Sports Medicine 43,267-286 doi:10.1007/s40279-013-0019-z
  • Mead MP, Gumucio JP, Awan TM et al. 2018. Pathogenesis and management of tendinopathies in sports medicine. Translational Sports Medicine. 1,5-13 doi:org/10.1002/tsm2.6
  • O’Neill S, 2017. PhD Thesis: A biomechanical approach to Achilles tendinopathy management
  • Rio E, Kidgell D, Moseley GL et al. Tendon neuroplastic training: changing the way we think about tendon rehabilitation: a narrative review. 2016 British Journal of Sports Medicine. 50,209-215
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