One of Daniel Lieberman’s prize finds was that the modern running shoe causes a runner to heel strike. Does this mean that when shod-heel strike runners run barefoot they instantly adopt a forefoot strike?
Most of the time, but not always, shod-heel strikers will shift to forefoot running when barefoot, but this shift in foot strike was supported by yet another study.
Study Finds Shoes = Heel Strike, Barefoot = Forefoot Strike
Ahn et al., (2014) found that shod-heel strikers who ran barefoot landed on their forefoot and reverted back to heel striking when they ran in the modern running shoe 🙁
In fact, the researchers found that heel strikers who ran barefoot and adopted a forefoot strike (let’s call them forefoot strike shifters), landed with a forefoot strike pattern with similar kinematics and mechanics to that of habitual forefoot strikers. That is, the forefoot strike shifters had similar ankle plantarflexion angles and knee flexion angles compared with habitual forefoot strikers.
The finding was interesting because the forefoot strike shifters were given no instruction on proper foot strike technique, and instead, were told to run with a self-selected, or preferred landing strategy when barefoot and shod.
Taken together, the findings suggest that barefoot running is enormously advantageous to a forefoot running learner.
The researchers also found that the forefoot strike shifters ran with a higher step frequency and a shorter stride length (reduced stride length by 5%) at slow, moderate, and fast speeds compared to the shod-heel strikers. And of course, the shod-heel strikers landed with their foot angled farther in front of them (over-striding).
But the clearest finding from the study that supports the popular conception that modern running shoes facilitate heel strike came from the differences in ankle-joint movement at touchdown.
All of the forefoot strike shifters landed with a more plantarflexed ankle when barefoot.
- Ankle plantarflexion (shown below) allows the foot to set-up for a forefoot strike landing.
In contrast, the forefoot strike shifters landed with a more dorsiflexed ankle at touchdown when in the modern running shoe.
- A dorsiflexed ankle (shown below) sets the foot up to make initial contact directly on the heel. This is the mechanism of which the modern running shoe facilitates, or directly causes heel strike when running, by effecting ankle-joint kinematics at touchdown.
In summary, the modern running shoe causes the forefoot to lift up (dorsiflexion) and barefoot running causes the foot to remain plantarflexed (the forefoot is parallel with the ground) at touchdown.
Because shod vs unshod (barefoot) conditions dramatically affect ankle-joint kinematics, these observations could better constrain predictions of the negative impact running shoes have on our natural biomechanics. To the inexperienced runner, if you run in the wrong shoe, you are going to heel strike.
More From Run Forefoot:
Ahn, AN., Brayton, C., Bhatia, T and Martin, P. Muscle activity and kinematics of forefoot and rearfoot strike runners. J Sport Health Sci, 2014; 3, 102-112.
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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