March 7, 2013
Shoes That Replicate Being Barefoot May Be Bad For Your Bones
WATCH VIDEO: [Caution on Barefoot Running Shoes]
Alan McStravick for redOrbit.com - Your Universe Online
In a new study by researchers from Brigham Young University (BYU), the benefits and pitfalls of this relatively new footwear are explored.
In the scope of human history, shoes designed specifically for running and exercise are a relatively new concept. In fact, shoes designed specifically for the runner didn´t truly exist in the US until the mid-1960s. A small company called Blue Ribbon Sports imported the new Tiger shoes from Japan. From this humble beginning, Blue Ribbon Sports was responsible for generating interest in the burgeoning running-shoe industry. In 1978, Blue Ribbon Sports changed their name to Nike and the rest is history.
Prior to this renaissance in athletic apparel, barefoot running was the only option for millennia. Despite the plethora of shoe options that are now available to the casual and serious runner, many athletes are opting for a more minimalist approach to their foot covering, bringing the concept of barefoot running back into vogue.
This backward-looking advancement in design is largely credited to a January 2010 article published in Nature. The article focused on a Harvard University study that detailed foot-strike patterns and the impact profiles of barefoot running as compared to running with shoes. Other large media outlets like The New York Times, Runner´s World and The Wall Street Journal picked up on this study and interest in barefoot running was instantly recognized.
It is important to note many people completely misinterpreted the initial study. The belief was fostered that barefoot runners suffered fewer injuries and were able to run faster than their shoe wearing counterparts. In fact, the study only claimed people “were able to land comfortably and safely when barefoot or in minimal footwear by landing with a flat foot (midfoot strike) or by landing on the ball of the foot before bringing down the heel (forefoot strike).”
Dr. Daniel Lieberman, one of the Harvard study leaders, claims mid and forefoot striking does not cause the sudden, large impacts that occur when you heel strike. As such, barefoot running allows the athlete to run on hard surfaces without suffering discomfort from the landing.
Runners who wear traditional running footwear tend to heel strike. This means the heel hits the ground first, causing the lower leg to come to a stop during the impact while the body continues to move across the knee. The initial impact of a heel strike is responsible for the heel having to absorb a full two to three times the body´s weight.
A midfoot strike allows a runner to land on the ball of his/her foot. This keeps the foot, at impact, in line with the hip. Often, a midfoot strike will keep the heel from even coming in contact with the ground. The larger foot surface area reduces overall force and allows the knees to act as shock absorbers.
A forefoot strike bears striking similarities to the midfoot strike. In this running pattern, the ball of the foot strikes the ground just below the fourth and fifth metatarsal. The body experiences less stoppage at impact and there is more shock absorption distributed among the knees, hips and back.
Going into more detail, Lieberman continues by saying that when running barefoot, the individual lands on the fourth and fifth metatarsal and then the heel goes down. This action, according to Lieberman, converts energy into what is known as rotational energy. Conversely, a heel strike causes the heel to come to a complete stop during the running motion. Despite their findings, the Harvard team points out that “no study has shown that heel striking contributes more to injury than forefoot striking.”
Further interest in minimalist running was sparked in the running community with the publishing of Christopher McDougall´s bestselling book 'Born to Run: A Hidden Tribe, Superathletes and the Greatest Race the World Has Never Seen.' In it, McDougall writes on the mechanics of running.
To support his claims, he focused on the Tarahumara Indians of Mexico. Members of this tribe are able to run 100 miles and more a day. The rugged Copper Canyon presents exceptionally challenging terrain. And they complete their daily runs wearing foot coverings made only of old tires and leather.
Anecdotal evidence, like that of the Tarahumura Indians, has also been coupled with the documented success of professional runners who have achieved stunning feats with nothing on their feet.
For instance, Abebe Bikila, running for Ethiopia in the 1960 Summer Olympics, took home the gold medal, winning the marathon in 2 hours, 15 minutes, 16 seconds. Though he had a shoe sponsor for the race, the shoes built for him ultimately didn´t fit and he chose to run without them, exactly as he had trained for the race back home in Ethiopia.
In the latest BYU study, conducted by a team of exercise science professors, they caution that runners wishing to make the transition from a traditional running shoe to the newly popular ℠barefoot´ five-finger running shoes should make certain the transition is completed slowly.
The study details how runners who expedite their transition in shoe style are at an increased risk of suffering injury to bones in the foot. These injuries could even lead to possible stress fractures. And with these new shoe varieties representing an estimated 15 percent of the $6.5 billion running shoe industry, the team believes the import of their study is evident.
“Transitioning to minimalist shoes is definitely stressful to the bones,” said Sarah Ridge, study lead author and assistant professor of exercise science at BYU. “You have to be careful in how you transition and most people don´t think about that; they just want to put the shoes on and go.”
For the study, the research team observed 36 experienced runners over a 10-week period. Their findings have been published online ahead of print in the journal Medicine & Science in Sports & Exercise.
Prior to running observation, each subject in the study underwent MRIs on their feet. At the start of the study, half of the participants were asked to gradually transition into five-finger minimalist shoes. The other half of the participants continued to run in a more traditional style of running shoe.
Runners who were switched to the minimalist shoe were advised to follow an industry-suggested protocol associated with this sort of footwear transition. In the first week, they were asked to only engage in a short one-to-two-mile run. Each week thereafter, they were advised to add another short run. After week three, subjects were asked to then add additional mileage to their runs as they felt comfortable.
At the culmination of the 10-week study period, each athlete again had their feet subjected to an MRI. The findings revealed those athletes who transitioned to the minimalist shoes experienced greater increases in bone marrow edema. This condition is indicative of inflammation that causes excessive fluid in the bone. Additionally, the minimalist footwear group also saw a higher incidence of stress injuries than those runners utilizing traditional running shoes.
“Whenever a bone is impacted by running (or some other repetitive action), it goes through a normal remodeling process to get stronger,” Ridge said. “Injury occurs when the impact is coming too quickly or too powerfully, and the bone doesn´t have a chance to properly remodel before impact reoccurs.”
Female runners in the footwear transition group, it was found, suffered more stress injuries to the foot than their male counterparts.
Much like Lieberman with the Harvard study, Ridge and her BYU cohorts offer a caveat to their study in the hopes it, too, will not be misinterpreted. They were careful to stress their findings do not necessarily mean a minimalist shoe is bad. They do, however, find contention with the industry-recommended protocol regarding transition to this shoe type. They claim, in order to minimize potential injury risk, the transition should occur over a period longer than 10 weeks and runs should be conducted at a lower intensity and mileage.
“People need to remember they´ve grown up their whole life wearing a certain type of running shoe and they need to give their muscles and bones time to make the change,” Johnson said. “If you want to wear minimalist shoes, make sure you transition slowly.”
Leading outdoor and athletic outfitter REI offers tips and guidelines on their website for anyone considering the move from a traditional shoe to the new minimalist footwear. One important point made regards runners who have low arches. As their site states, “Heavily pronating runners — those whose feet flatten during weight-bearing exercise — may struggle to adjust to the lack of arch support,” offered by these shoes.
Ridge and her co-authors on the study, BYU exercise science faculty Wayne Johnson, Ulrike Mitchell and Iain Hunter state this will be but the first of many studies to focus on the minimalist running shoe. The plan, over the next several months is to publish enough research that a clear set of recommendations will emerge for anyone who might be considering making the switch to this primal influenced footwear.