When shopping for shoes, many running stores will recommend looking at the height of your arch to determine what kind of shoe you need. But, is arch height and effective way to determine what shoes you need?

People have arches that range from very high and immobile to very flexible and almost completely flat, so you would think that arch height plays a role in the biomechanics of your foot when you run.

To get to the core of the function of the stiffness, height, and flexibility of your arch when you run, we will take a look at some of the recent scientific studies on the topic. More importantly, we’ll examine what roll arch height plays in running injuries and shoe selection.

Arch height according to studies

Studying arch height as it relates to injury seems to have come into fashion in the 1980s or 1990s, when military doctors and academics examined it as a possible factor in injury rates among recruits.

A 1999 study, for example, connected both excessively high arches and excessively low ones with overuse injuries in the foot and leg in a group of 449 naval recruits.

Prior to that, a 1993 study at the University of Calgary suggested that a stiffer (and higher) arch in a runner could affect how the ankle joint “coupled” the foot and the lower leg, transferring more force from impact through the ankle joint and into the leg and knee.

Other work suggested that flat feet were more prone to pronation, which at the time was thought to play a central role in many overuse injuries in the lower leg.

Going along with this logic, biomechanics researchers and shoe designers hypothesized that lower arches would need more support to prevent pronation, while higher arches would need more cushioning to reduce the forces going through the foot.

But there were some problems with how these and other studies evaluated the role of arch height and stiffness. For one, arch height wasn’t so much measured by researchers as it was subjectively described.

Flat feet vs. high arch

A study done by David Cowan and others in the 1990s looked at the consistency of arch height assessments done by various medical clinicians. Some 246 military recruits had their feet examined by several different orthopedists and podiatrists, who were instructed to classify the feet from “1” (clearly flat-footed) to “5” (clearly high-arched).

While the doctors were at least passable at identifying flat feet, there was very little agreement on what should be classified as “clearly high-arched.” This called into question the reliability of subjective judgments on arch height, even by trained doctors.

Further problems developed when the arch height-to-shoe model was tested, again in a study of military recruits. A very comprehensive study of Air Force recruits found no difference in overall injury rate when recruits were given the “proper” shoe for their arch height versus when all recruits had a standard stability shoe, regardless of their arch condition.

While influential, this study’s findings were confounded by the fact that they used the same subjective method of classifying arches as high or low that was called into question by Cowen et al. Additionally, running is different than military training, so we have to keep that in mind as well.

Reliability of the arch ratio test

This might’ve been the end of the story if not for careful investigation and reexamination of the idea of arch stiffness by persistent researchers. A 2001 study by Dorsey Williams, Irene McClay, and Joseph Hamill developed an “arch ratio test,” using objective measurements of the length of the foot and the height of the arch while standing.

Unlike the more subjective observation-based classification of arch height, Williams et al. showed that their arch ratio test was highly reliable, both in repeated measurements by the same experimenter and among different observers.

The test results

Using their arch ratio test, Williams et al. gathered two groups of runners, one with arches in the highest 10% of the population when measured by the arch ratio and one from the lowest 10%.

When the researchers examined the injury histories of each group of runners, the overall number of injuries between the groups was very similar—64 injuries in the low arched group and 70 in the high arched group. But the distribution of injuries (that is, where they occurred) was quite different.

Lower arched runners tended to have more soft-tissue injuries and injuries on the medial (inside) part of the leg, while high-arched runners tended to have injuries on the lateral (outside) part of the leg and more bony injuries like stress fractures and shin splints. In a later paper, the researchers identified arch and leg stiffness as the likely cause for the differences in injury location.

Biomechanically speaking, this makes sense—a flexible arch would flatten out on impact, spreading out the force over a longer period of time and also moving the force from the ground to a more medial location on the foot. A higher arch would be stiffer, transferring the impact force with the ground more quickly and directing it up the leg more laterally. However, this study was fairly small, and needs to be confirmed in larger groups of runners.

Arch height and injuries

While there is more to be discovered about the role of arch height in injuries, the recent evolution of the research on the topic allows us to have a more nuanced idea of how your arches might affect your daily running.

Overall, whether you have a high or low arch will not affect your risk of injury, nor should it affect what type of shoe you choose, but it could affect where you get injured.

People with high, stiff arches are probably more susceptible to bony injuries on the outside of their foot, ankle, and leg, while people with flat and flexible arches are more likely to get soft tissue injuries and problems on the inside of their lower body.

While low-arched runners seem to get a better bargain, don’t forget that Achilles injuries, muscle strains, or other soft tissue problems can be just as disruptive as a stress fracture or stress reaction.

Armed with this information about your arch height and potential injury-risk, you can develop a better protocol for your injury-prevention and strength training. For example, if you have low arches, you can spend more time strengthening your feet and lower legs to prevent muscle strains and injuries like plantar fasciitis and achilles tendonitis. On the other spectrum, if you have high arches, you can focus more effort on improving the strength in the muscles around your shin and reducing impact forces by improving your cadence.