Imagine trying to withstand a force 12 times your own body weight. Sounds impossible, yet that’s what your Achilles tendon (AT) does during something as simple as running. As the strongest tendon in the body, it’s essential for every movement. But the same repetitive motions that strengthen this tendon can also lead to injury. Achilles tendinopathy, pain and swelling along the tendon, is one of the most common overuse injuries in both runners and dancers. So how can similar motions account for both AT strength and damage?
I’ve struggled with Achilles pain for over ten years. While running still aggravates it, I’ve danced competitively for years without much trouble. By looking at how the Achilles tendon responds to the repetitive impact of running versus the dynamic movement of dance, we can start to understand what might make it strong and what pushes it past its limits.
About the Achilles
Tendons act like springs connecting muscle and bone, storing and releasing energy as we move. The AT is especially efficient at this, stretching slightly to cushion each step and then snapping back to help propel us forward. Athletic training often makes the tendon stiffer, meaning it can handle greater forces with quicker responses. But if it becomes too stiff, it can’t absorb shock as well, increasing the risk of small tears or even rupture. Beyond genetics, our everyday movements and training styles also shape this delicate balance between power and protection.
Running versus Dance
Let’s look at a study that tracked running-related AT injuries in recreational runners like me. Running is high-impact and repetitive, so foot contact and tendon stretch are the same with each stride. Runners who developed Achilles injuries tended to land with their knees and ankles more bent, causing a deeper stretch in the tendon. Over thousands of steps, this can create micro-damage, contributing to stiffness imbalances and chronic tendinopathy.
We know running training can strengthen tendons, and we have seen how it can cause damage. So how is dance different? Despite having some high impact, dance involves more multidirectional and variable loading. Another study looked at AT stiffnesses in three groups: professional ballet dancers, running-intensive college athletes, and non-running-intensive college athletes. Along the tendon length, dancers and runners had essentially the same stiffness, greater than that of the non-running intensive group. However, across the AT width, the dancers showed more stiffness than even the runners. The authors suggest the stiffness across the width shows the tendon adapting to the varied direction of loading in dance.
Conclusion
Achilles tendon behavior is challenging to study; it’s both shaped by movement and constantly changing because of it. While research on dancers is still limited, these studies suggest that different activities create unique adaptations. For me, that helps explain why my Achilles seems better suited to dance than running. The good news? If one type of exercise causes pain, it doesn’t mean you’re stuck. Both you and your tendons can adapt to new ways of moving.
For more reading check out the full papers: Skypala et. al, and Gonzalez et. al.
Feature image edited from Injurymap “Pain on the back of the heel”, Hoka Running Shoe, and Jim Lamberson | Wikimedia Commons.
