Preventing Foot Stress Fracture From Running

There’s strong evidence supporting the idea that a foot stress fracture from running may be avoided by running with a forefoot strike, but to better your chances of getting such an injury is to run forefoot in running shoes that offers good ground-feel clarity, shoes like minimalist shoes (i.e. shoes with a thin sole without any thick compressible foam, gel or plastic underfoot materials). In turns out, there’s a big difference in plantar pressure stress between runners who run barefoot or in barefoot-like shoes vs runners who run in thickly cushioned running shoes.

How to Prevent Foot Stress Fracture From Running?
Runners who wear thickly cushioned running shoes may strike the ground with greater downward force that generates abnormally high doses of plantar pressure stress on areas of the foot not structurally capable of enduring such heavy pressure points. Over time, running in this way, with increases in peak plantar stress, may boil into a stress fracture in the foot as compared with running barefoot or in barefoot-like minimalist shoes.

Preventing Foot Stress Fracture From Running

As we so well know, injury prevention efforts in running mainly target factors such as reducing impact by adding more layers of cushioning under the foot. But what’s so scientifically interesting is that many studies (references listed at the end of the article) have found the same basic conclusion: decreases in ground-feel at the feet may lead to increases in unusually high peak plantar pressures, especially on the midfoot. Also, the softer and thicker the underfoot cushioning, the greater the peak plantar pressures, potentially putting more fracture-inducing stress on the foot during running. 

It gets worse. Thick shoe cushioning was found to completely mask the feel of high impacts during running, leaving runners incapable of truly feeling abnormal rises in plantar pressure and impact stress on the foot.

Evidence in alignment with this came from the pioneering work by Dr. Steven Robins, MD, who found that runners who ran in thick cushioned running shoes was exposed to more plantar impact because cushion thickness significantly diminished transmission of mechanical transients which are adequate stimuli to proprioceptors. In simple terms, when your feet are unable to feel the ground, due to thick underfoot cushioning, the failure to capture some sensory scope of the ground at the feet may be accompanied by a greater downward force and a greater push force of the feet.

What is more, thick underfoot cushioning may go against the body’s natural impact-avoidance behavioral response that you would get if you were to run barefoot or in thin-sole running shoes. In fact, a 1996 study in the journal Clinical Biomechanics discovered that running over harder plantar surfaces with minimal underfoot protection resulted in stark reductions in peak plantar pressure on account of the runners reflexively adjusted their landing intensity to land more lightly. 

Preventing Foot Stress Fracture From Running: Run Barefoot?
Less protection means less impact? When you run in barefoot-like shoes, or even run barefoot, especially on harder surfaces, your initial reaction is to reflexively land with your foot in a better position that’s closer to your center mass with better forefoot strike precision, which helps reduce the braking force, but also you land with less push force. Not to mention, you get a faster withdrawal retraction, or removal of the foot off the ground. The net effect of all this is that you’re better able to naturally assemble a lighter, softer, more responsive landing strategy that may give you real protection against dangerous rises in plantar pressure.

Underfoot ground-feedback can really help you reign in your worst mechanical impulses, like pounding the pavement and landing heel-first but what enables the body to make such important mechanical adjustments in the absence of underfoot-cushioning?

Its ALL About Proprioception!

When you can feel the ground more fully with your feet, you have better proprioception. Proprioception is defined as the constant feedback loop within your nervous system that informs your brain about what position you are in and what forces are acting upon your body at any given point in time. The body’s proprioceptive system also plays an important role in maintaining the body’s natural mechanical defenses against high impacts, which is proven to be optimized barefoot.

How exactly do our feet importantly contribute to proprioception?

The underfoot is incredibly densely populated with groups of nerves that belong to the proprioceptive system whereby all the sensory elements that converge at the feet when barefoot is sent to the central nervous system (spinal cord and brain). From here, a range of other nerves switch on a range of muscle and reflexive responses that are key organizers of more functional movement patterns and other biomechanical outputs that helps produce impact-avoidance behaviors. This is precisely the reason that you don’t end up with high impacts crashing into the foot, or the leg when you barefoot, despite surface hardness, AND is why increased barefoot running training fits so nicely into the role of injury prevention.

But when the proprioceptive system is blocked at the feet, with thick shoe cushioning, it may compromise the proprioceptive feedback loop which has proven to cause the default reaction in encouraging forceful footfalls as well as producing more enormous and more immediate varieties of impacts on the feet as compared with running barefoot or in minimalist shoes. In essence, instead of adding protection, thickly cushioned running shoes seems to take the protection away. Likewise, if cushioned running shoes can’t reduce all the impact, how can they prevent all injuries?

Obviously, there are countless variables involved, and many more to be discovered, that cause running-related injuries, but certain running shoes, namely thick cushioned running shoes are on record for disrupting plantar proprioception, resulting in a more heavy footstrike intensity with greater impact production of which injury troubles tend to begin.

This is why you can do better with your injury prevention efforts by integrating barefoot running in your regiment as barefoot running is most effective to tap into the proprioceptive power that’ll assist you in developing a landing strategy that’s so brief that certain impact variables are not fully produced on the foot and leg.


References:

Chen et al. Influence of sensory input on plantar pressure distribution. Clin Biomech, 1995; 10(5):271-74.

Hennig EM., Valiant GA and Liu Q. Biomechanical variables and perception of cushioning for running in various types of footwear. J Appl Biomech, 1996; 12(2):143-150.

Pell RFt, Khanuja HS, Cooley GR. Leg pain in the running athlete. J Am Acad Orthop Surg. 2004;12:396-404.

Robbins et al.  Sensory attenuation induced by modern athletic footwear. J of Test and Reg,  July 1988.

Sharma J, Golby J, Greeves J, Spears IR. Biomechanical and lifestyle risk factors for medial tibia stress syndrome in army recruits: a prospective study. Gait Posture. 2011;33:361-365.


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Bretta Riches

"I believe the forefoot strike is the engine of endurance running..."

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.
Bretta Riches

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