Your feet are the foundation of your body and if they are strong, you are less likely to have common running injuries. Arch height is much less important if your feet are strong. Many world class distance runners have very low arches and massive “overpronation”, but their feet are strong—often from growing up being barefoot. Research has shown that those who go through a foot strengthening protocol are 242% less likely to be injured, making it the statistically best way to reduce running injuries. When your feet and lower legs are not strong enough, other parts of the body have to compensate and take on strain and shock that can often be the cause of injury.

Now that we’ve established the importance of strong feet, regardless of arch height, we need to address how to strengthen the feet. The good news is that a lot of foot strengthening exercises are relatively easy and can be incorporated in to everyday life without taking time away from your day. Here are some starter foot strengthening tips:

• The single best exercise for building your landing gear is to simply balance on one foot whenever possible. You can do this as a dedicated exercise at home while barefoot, or in situations like waiting in line to pay for groceries, etc. Just pull one foot slightly off the ground while in line…no one even has to know! For maximum effect, and to engage hip stabilizers (important!), work up to balancing on the forefoot with the heel 1/2″ to 1″ off the ground. Pull your big toe out as straight as possible and engage it! To increase difficulty and effectiveness, close your eyes. We like to lift the free leg and move it front, back, and sideways or reach the arms up or sideways as well. You can even graduate to doing these exercises on something soft to increase the difficulty.
• Research has shown that simply wearing foot-shaped, zero drop barefoot style shoes regularly for a few months was similarly effective to going through a foot strengthening exercise program. Imagine doing both! For casual shoes, we recommend brands like Splay, Lems (some), Vivo Barefoot, Xero Shoes and others you can find on Anya’s Reviews.
• Wear Correct Toes toe spacers and do exercises while wearing. Many people are blown away by how much their balance instantly improves by simply putting on some Correct Toes. Run with Correct Toes regularly as well if you have foot-shaped running shoes like Altra or Topo. We recommend getting your socks a size bigger as well to facilitate more comfort and toe splay.
• Simply take your shoes off when they don’t have to be on. Go barefoot whenever possible or reasonable and within what your body is ready to handle.
• Barefoot running is a simple and very effective foot strengthening exercise. Start on carpet or grass for 30 seconds to a minute and add 30 seconds more every few days (as long as pain free during & the next day). Variable surfaces like grass or dirt will provide the most foot strengthening.
  We suggest doing this at the start or end of your runs…just don’t put your shoes on at first, or take them off at the end of your run. Those who can comfortably run 20 minutes barefoot easily will have built very good foot strength.
• Single leg heel-raises with 1″ under the toes are another good foot strengthening exercise (running-physio.com/pf-new-research)
• Pull a towel in with your toes while watching TV or reading a book. Picking up marbles and moving them from one place to another is another variation.

See below from: http://www.borntorun.com/where-are-the-flat-feet/

Flat Feet Don’t Actually Cause Injuries or Foot Problems

If you listen to the physiotherapy/orthotic industry, there is an epidemic of flat feet. The BTR coaching community have lost count of how many clients have visited us and claimed that they have flat feet. I only remember two clients with flat feet from the many 100’s of pairs of feet I’ve seen. Of clients claiming flat feet, some may have natural feet, but many present high-arched feet, the opposite of what they think they have (read our earlier post good, bad, ugly part 3 feet for our definition of natural, flat and normal feet).

A widespread belief is that persons with flat feet are at increased risk of injury. Cowan (1993) studied US Army Infantry trainees over a 12-week training program and evaluated the risks of exercise-associated injuries among men with flat, normal and high-arched feet. The results showed an association between arch height and risk of injury. The 20% with the flattest feet were at the lowest risk! The higher the arch, the higher the risk of injury!

“Results of this study indicate that having low arches (“flat feet”) was not associated with an increased incidence of injury regardless of how we measured arch height. Rather, there was a significant linear trend for increasing risk of injury with increasing arch height for seven measures or indices of arch height, with flat feet at lowest risk of injury.”

This should not have come as a surprise to Cowan if he was familiar with the Hoffman (1905) study. Hoffman studied unshod populations in Asia and Africa and found that “The height and shape of the longitudinal arch have no bearing on the strength or usefulness of the foot. The height of the arch appeared to bear no relationship to the gait. In shoe-wearers, the affection commonly called ‘flat-foot’ is often associated with more than ordinary eversion (pronation) of the foot on standing and walking. This eversion is due not to the low arch, but to the associated weakness or stiffness of the joints of the foot and weakness of the muscles”. See fig 1 for the variety of strong, flexible and functional feet that Hoffman found in unshod populations.

 

Weak, inflexible feet are the problem, not height of the arch. A Natural Foot is strong and elastic and provides a wide, stable platform for all functional-human movements including; standing, squatting, lifting, walking and running. A Natural Foot will often be incorrectly misdiagnosed by medical professionals as a flat-foot.

References:

Cowan DN. (1993). Foot Morphologic Characteristics and Risk of Exercise-Related Injury. Archives of Family Medicine, 2, 773-7.

Hoffman, P. (1905). Conclusions drawn from a comparative study of the feet of barefooted and shoe-wearing peoples. The Journal of Bone and Joint Surgery, 3, 105-136.