There are plenty of reasons your shins hurt when running. Reasons such as running on hard surfaces, the wrong type of footwear, training volume and improper biomechanics. However, running barefoot and running in zero drop minimalist shoes, like the Vibram FiveFingers, are thought to reduce the incidence of shin splints by encouraging less ankle dorsiflexion at touchdown, thereby allowing for less of a heel strike and more of a forefoot strike landing pattern.
Incidentally, it turns out that many runners who transition from conventional running shoes to the Vibram FiveFingers or running barefoot experience some form of shin splints. What can account for this?
Why Your Shins Hurt When Running Barefoot or in the Vibram FiveFingers
It has been said that excessive use of the toe flexors is one cause of shin splints in runners (Viitaslo and Kvist, 1983). Specifically, what sets apart the foot strike mechanics in barefoot running and running in the Vibram FiveFingers from running in regular running shoes is the use of toe flexion at touchdown and may hint at why newbie barefoot/Vibram runners get shin splints.
When we run with a forefoot strike in regular running shoes, most of us keep our toes very relaxed and non-flexed at touchdown, shown below:
See how in the above photos, the toes are pointed down or are more parallel with the ground at landing? This means the toes are relaxed and are not fully flexed at touchdown as they are when running barefoot or in the Vibram FiveFingers which is shown below.
When we run barefoot or in the Vibram FiveFingers, our toes have a greater tendency to flex up, and spread apart right before and at touchdown. This toe flexion during barefoot and Vibram running increases muscle activity in the anterior shin muscles and may cause shin splints in a beginner barefoot or Vibram runner until the shin muscles and toe flexors become stronger and fully adopted. Note that this toe flexion is not a bad thing, it is just a reflexive, natural response to running without external protection on the feet and should be embraced.
A bonus of this increased toe flexion upon touchdown during Vibram and barefoot running is that it increases contractions in the arch muscles, therefore stimulating stronger, higher arches, which is great for those with flat feet.
From what I’ve researched, it is unclear about why barefoot/Vibram runners have this response in toe flexion and shod runners do not. Perhaps, it is related to the increased sensory nerve activation in the soles of the feet when running without shoes or in shoes without cushioning. Comparatively, it is quite possible that the lack of toe flexion observed in most shod forefoot runners may put them at risk of developing weaker arches as compared with barefoot runners.
So, if you have shin splints from running barefoot or from running in the VFF’s, I widely doubt that it is related to running on pavement, training volume, or a biomechanical flaw. The condition is most likely due to the heightened nerve stimulation on the bottoms of the feet which is triggering the reflex action of toe flexion right before the foot strikes the ground.
Nonetheless, just be patient with this injury, it will get better, and remember, never to stretch!
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Minimalist Shoes Are Perfect for Any Runner, if You Know How to Run Properly in Them
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Why It’s Crucial to Run Forefoot When Fatigued
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Viitasalo JT and Kvist M. Some biomechanical aspects of the foot and ankle in athletes with and without shin splints. Amer J Sports Med, 1983; 11(3):125-130.
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.