Treatment for running-related Achilles tendon injuries includes foot strike modification –meaning change your foot strike from a heel strike to a forefoot strike. Heel lifts/inserts should also be avoided because they encourage heel strike during running.
Why Heel Inserts Cause Achilles Tendon Injuries
Heel inserts are used to treat runners with Achilles tendon injuries. The premise of using heel inserts is to increase shock absorption under the heel, thereby reducing impact on the Achilles tendon during running.
Yet the problem could worsen with heel lifts because they encourage heel strike during running which increases the ground reaction force on the Achilles tendon.
A study by Dixon and Kerwin found that heel strike runners who wore a 15 mm heel lift had significant increases in maximum ankle moments and maximum Achilles tendon force compared with the barefoot runners. However, the forefoot strike runners were found to have a standardize effect and showed no significant differences in maximum ankle moment or Achilles tendon force.
The researchers also found that the heel strike runners who wore 15 mm heel lifts had an increase in ankle moment at the time of maximum Achilles tendon force which resulted from the increase in the ground reaction force.
- Essentially, no evidence was found that peak Achilles tendon force was reduced with an increased heel lift.
Overall, the higher the heel, the smaller the length of the Achilles tendon moment arm. This means that the Achilles tendon has limited space to stretch and recoil to store and release elastic energy during running.
And, from an injury standpoint, raising heel height has adverse influences Achilles tendon health because it increases the maximum force on the Achilles tendon.
Though, forefoot strike runners have a relatively high Achilles tendon force, they have a significantly lower magnitude of the ground reaction force which reduces loading on the tendon.
- Many elite runners are forefoot strikers and Achilles tendon injuries are much lower compared to joggers, who are mostly heel strike runners.
Of course, elite runners may be well-conditioned, but the fact that Achilles tendon injuries are lower in habitual forefoot runners debunks the belief that high Achilles tendon force causes Achilles tendon injuries.
Don’t Heel Strike! – Research shows that heel striking is a major pitfall for runners.
Barefoot Running – It’s not a fade. It’s actually one of the best ways to improve the sensory networks in your feet and joints.
Shoe Reviews – A forefoot runner’s guide to minimalist shoes.
When Your Knees are Out of Whack – Learn how to avoid runners knee.
Dixon S and Kerwin G. The influence of heel lift manipulation on Achilles tendon loading in runners. J Appl Biomech, 1998; 14, 374-89.
BSc Neurobiology; MSc Biomechanics candidate, ultra minimalist runner & founder of RunForefoot. I was a heel striker, always injured. I was inspired by the great Tirunesh Dibaba to try forefoot running. Now, I'm injury free. This is why I launched Run Forefoot, to advocate the health & performance benefits of forefoot running and to raise awareness on the dangers of heel striking, because the world needs to know.
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