Why running barefoot or in minimalist shoes may be beneficial

Humans have been walking and running without shoes for millions of years, but there has been a recent surge of interest in going barefoot among runners, the media and the sports medicine community. Although we know little scientifically about barefoot running, many diverse opinions have been expressed on the topic.

As often is the case, extreme views tend to get the most attention. At one end of the spectrum, proponents of barefoot running argue that running without shoes is more natural and better for you and that shoes cause injury. At the other end of the continuum, skeptics argue that barefoot running is a dangerous fad to be avoided.

Not in dispute is the fact that running is an efficient and popular way to achieve fitness. Running and jogging participation in the United States has increased 10.3 percent in the past two years, enjoyed by some 35.5 million Americans, according to the National Sporting Goods Association.

Much of the excitement about running barefoot has resulted from the high injury rates among shod (shoe wearing) runners. The yearly incidence of long-distance running injuries in recreational and competitive runners is high with variability ranging from 19.4 to 79.3 percent, according to The British Journal of Sports Medicine. Two of the most recent studies found incidence rates of 54.85 and 59 percent, more than half of runners, as reported in The Scandinavian Journal of Sports Medicine. Injury rates are as high as 90 percent in runners training for marathons.

Of course runners are particularly interested in learning how to reduce the likelihood of injury. According to a an article in a 1987 edition of Medicine Science and Sports Exercise, it was shown that barefoot runners had lower injury rates.

What we know
To gain some insight about this trend toward barefoot running, lets look at what runners do differently when they take their shoes off. Given the available research, here is what we know.

1) Barefoot running requires a mid-foot to forefoot ground striking pattern compared with a rear-foot heel strike pattern that tends to come with running in shoes. This change in the foot-striking pattern results in a shorter stride length and higher step frequency (cadence) in barefoot runners. According to an article appearing The International Journal of Sports Medicine in 2005, "These stride differences may possibly reduce initial impact forces." The idea being that if one generates less impact forces, then that person will have less chance of injury.

2) Runners wearing shoes usually have a rear-foot or heel-striking pattern. Heel striking leads to a more extended and stiffer knee and ankle than experienced by runners who uses a mid-foot to fore-foot striking pattern. Runners utilizing a mid-foot or fore-foot impact pattern are in a better position to dampen the tremendous forces seen at foot strike. The ability to reduce these forces may be one of the merits associated with unshod running injury prevention.

What we don't know
We simply do not yet know if experienced habitually barefoot runners have fewer injuries than habitually shod runners. This is hard to test without correcting for confounding factors such as form as well as musculoskeletal strength and training intensity, which vary among both populations of runners.

Given the available research in this area, it would appear that if you run in shoes you are somewhat reliant on the integrity of the shoe to reduce the forces applied at impact. And if you run barefoot you will be reliant on the integrity of your own feet, ankles, knees and hips to reduce the forces applied upon impact with the ground.

It may be that runners who wear shoes and have had few injuries have already adapted a more barefoot running style, meaning they tend to land on the mid- to fore-foot. And those who suffer from frequent injuries chronically overstride and cause greater forces that may prove detrimental to the tissues involved.

It may also be that in order to keep the tissues of the feet, ankles, knees and hips safe from injury that a combination of barefoot training, to strength our intrinsic supports, and shod running, as an extrinsic support, will lead to less injury.

Whether an individual gets injured or not may be a result of how one runs versus what is on ones feet at the time.

Performance
OK, so what about performance? Most elite runners prefer to use shoes because they protect the foot and allow one to run on rough surfaces without worrying about foot placement. But barefoot runners, such as Abebe Bikila and Zola Budd, have set records in the marathon and shorter distances.

The world record holders for almost every long distance running event are fore-foot striking runners who race and sometimes train in racing flats or other kinds of minimal shoes. In addition, economy seems to be improved by being barefoot or in minimal shoes.

Several studies appearing in Medicine Science and Sports Exercise, International Journal of Sports Medicine, and the Journal of Sports Medicine and Physical Fitness have shown that barefoot or minimally shod runners are between 1 and 3.8 percent less costly per unit mass and distance, which is due in part to less shoe mass, which increases running cost by approximately 1 percent every 100g.

(Here cost refers to caloric cost used to move one's mass over a distance. This is measured by oxygen consumption. The more oxygen used means more calories used. If two people of the same size run the same distance then the one who used the least amount of oxygen to complete the distance would be said to have a greater running economy.)

The recent resurgence of barefoot running may be a result of the growing belief that barefoot running is better for the body than using supportive footwear. The expectation is that injury rates will decrease as runners encounter lower impact-related forces when barefoot. To date, most supportive reports for barefoot running have been anecdotal. Future research should examine the effects of barefoot running on both injury reduction and performance.

As the research on this topic continues to mount I will keep you informed. So before starting any new exercise regimen, be sure to consult you physician.

Greg Renfro, the sports medicine supervisor at Langlade Hospital in Langlade, Wisconsin, has presented and published at the state and national levels on topics from optimal performance to injury prevention. Renfro previously served as a strength and conditioning specialist at the U.S. Olympic Training Center in Colorado Springs, Colorado. He holds a degree in exercise physiology from the University of Wisconsin-La Crosse.