The Science of Barefoot Running

The following report by Steve Nearman appeared in the latest issue of the Journal of the American Medical Athletic Association, and is reproduced here with the AMAA‘s permission.

Daniel Lieberman, PhD, known in the running community as the “Barefoot Running Professor” has his favorite motto when ad- dressing his favorite topic.

“If you think barefoot running is a fad, then it’s a two-million-year-old fad,” he told the audience of 175 doctors and sports medicine professionals at the 40th Annual Sports Medicine Symposium at the Boston Marathon in April, sponsored by the American Medical Athletic Association.

Dr. Lieberman, a professor of human evolutionary biology at Harvard University, has become a cult hero of sorts for the growing popularity of barefoot running. While he advocates that some people might benefit from running with no shoes or minimal running shoes, he is quick to point out that your foot- wear should depend upon your running style.

“The lesson from barefoot running,” said Dr. Lieberman, who claims he runs barefoot at times during his training, “is not about whether you run with or without shoes. What’s more important is your running form. But what is on your feet can affect your form.”

“If you run with poor form, you are better off in shoes that protect you. But if you are a forefoot striker, you might consider running barefoot or in minimalist running shoes.” And if you do decide to try barefoot running, he said, “do so gradually and carefully. It is crucial to build up foot strength, calf strength, and learn good form. But most importantly, be a skeptic.

Do what you want, have fun, avoid injury, don’t fix what ain’t broke.”

With his extensive research on barefoot running, Dr. Lieberman has discovered significant benefits to running without shoes or with minimal shoes. Some of this research refutes what the running shoes companies have been pitching for decades about the need for padded running shoes to reduce injuries from pound- ing the pavement.

According to Dr. Lieberman’s research, injury rates have not declined in 30 years even as major advances seem to have been made in running shoe technology over that time. Some 30 to 70 percent of habitually shod (shoe-wearing) runners are injured each year, he added. And with all the advances in motion-control running shoes, Dr. Lieberman stated, there is no evidence that they prevent injuries.

“About 75 percent of runners today are predominantly heel strikers,” Dr. Lieberman said. “Heel strikers generate a collisional impact. Running shoes make it comfortable to heel strike.”

In Dr. Lieberman’s extensive writings, he has said “Humans evolved to run millions of years ago, and before the mid 1970s all humans ran in either no shoes or very minimal footwear such as sandals, moccasins or thin running flats. A basic prediction of evolutionary or Darwinian medicine is that the human foot is likely to be well adapted to running long distances barefoot. If so, then contrary to popular belief, the bare foot may be well suited for running long distances without requiring modern, heavily cushioned, high-heeled running shoes.”

Dr. Lieberman was joined at the AMAA panel by Irene Davis, PhD, director of the newly-created Spaulding National Running Center at Harvard Medical School and Mark Cucuzzela, MD, professor of family medicine at West Virginia University, who ran a 2:37 marathon this year at Boston at age 44.

Drs. Lieberman and Davis have joined forces at Harvard and are researching the barefoot running issue together.

Dr. Davis is considered one of the foremost experts on the biomechanics of running and is known for her advocacy and innovative work for barefoot and minimal footwear running.
A preponderance of her research came from the years she spent as a professor in physical therapy and as the director of the Running Injury Lab at the University of Delaware. Over the past 20 years, she has established relation- ships between faulty mechanics and overuse injuries such as tibial stress fractures and patellofemoral disorders. This has led to the development of innovative interventions such as gait retraining, aimed at altering faulty running mechanics.

Her interests also include the mechanics of barefoot and minimal footwear running and its effect on injury rates. A barefoot runner herself, Dr. Davis serves as a consultant for patients withlower extremity problems related to overuse problems.

Dr. Davis recounted a story about a 55-year- old male patient who suffered from stress fractures. As a rear-foot striker, his body experienced increased impact with the ground. So the man changed his form into a forefoot striker and he subsequently developed Achilles tendonitis. When he returned to his old rear- foot strike ways, the stress fractures returned.

“The impact-related loading was greater in those with histories of stress fractures,” Dr. Davis concluded. “Unless the underlying mechanics are addressed, injury rates may increase.” To that end, Dr. Davis said she “re- trains” runners in a two-week course consisting of eight sessions in her office. Her retraining teaches athletes to land softer on their forefeet rather than harder on their heels.

“Tibial shock is reduced by 30 percent,” she said, thus reducing impact-related injuries to the ankles, bones and knees. She further added that by running on your forefoot, “injury risk is reduced by taking shorter strides.”

Dr. Davis also cited a study conducted in 1989 by Dr. Bernard Marti. He looked at 5,026 runners who participated in a marathon and discovered that runners in shoes costing $95 or more were twice as likely to get injured as runners in shoes which cost under $40. Interestingly, pronation tendency appears to be greater in motion control shoes, something that counters conventional logic.

We also are now finding that “static and dynamic stability decreased in running shoes,” a conclusion Dr. Davis said she has just reached. She will be announcing more results of her re- search on this topic soon.

Dr. Davis also referenced her and Dr. Lieberman’s research as published in Nature last year. In the abstract of that article, it states: “Humans have engaged in endurance running for millions of years, but the modern running shoe was not invented until the 1970s. For most of human evolutionary history, runners were either barefoot or wore minimal footwear such as sandals or moccasins with smaller heels and little cushioning relative to modern running shoes. We wondered how runners coped with the impact caused by the foot colliding with the ground before the invention of the modern shoe.

“Here we show that habitually barefoot en- durance runners often land on the fore-foot (fore-foot strike) before bringing down the heel, but they sometimes land with a flat foot
(mid-foot strike) or, less often, on the heel (rear-foot strike). In contrast, habitually shod runners mostly rear-foot strike, facilitated by the elevated and cushioned heel of the modern running shoe.

Kinematic and kinetic analyses show that even on hard surfaces, barefoot runners who fore-foot strike generate smaller collision forces than shod rear-foot strikers. This difference results primarily from a more plantarflexed foot at landing and more ankle compliance during impact, decreasing the effective mass of the body that collides with the ground. Fore-foot- and mid-foot-strike gaits were probably more common when humans ran barefoot or in minimal shoes, and may pro- tect the feet and lower limbs from some of the impact-related injuries now experienced by a high percentage of runners.

The take-away on Dr. Davis’ presentation: “we don’t listen to our bodies, we were not built for the speeds we are running, we push ourselves too hard, we were not meant to land on our heels and we’ve taken away the function of our feet by putting them in shoes.”

Dr. Cucuzella agreed with Drs. Lieberman and Davis that educating people about running in proper form is crucial. “The science is behind this, and I agree 100 percent,” said Cucuzella, who frequently performs injury-prevention seminars. He even owns the first running store to sell only minimalist running shoes. He is not alone in his vision of increasing minimalist shoe sales: at this year’s Boston Marathon expo, quite a number of vendors were selling minimalist running shoes, including several of the major running shoe manufacturers.

As a Lieutenant Colonel in the Air Force Reserves, he is coach and captain of their marathon team and designs programs to reduce running injuries in military personnel.

His passion for injury prevention is highly personal. After he was diagnosed with arthritis in his toe joint, Cucuzella was told by several specialists to stop running. But Cucuzzella was determined keep going, so he used his research skills and knowledge as a physician to develop low-impact techniques so as not to further damage his joint. He also observed the elite runners, and the way they landed under their center of body mass. eventually, he found ChiRunning.

He presented the audience with a video of himself running barefoot in the historic roads of the Antietam National Battlefield, illustrating from behind as his feet met the hard surface with the soft landing he has perfected.

The panel discussed the pros and cons of forefoot striking barefoot or in minimalist footwear.

Advantages:
•    Forefoot striking strengthens the muscles in the foot, especially in the arch. A stronger
foot will pronate less;
•    Barefoot running can feel comfortable because of minimal impact forces provided
the feet are properly callused;
• With the natural spring of the stride, you may expend less energy to forefoot strike.

Disadvantages:
•    Thick-soled shoes are much more forgiving and protecting when running over glass,
sharp objects, ice, roots, etc.;
•    If you have been a heel striker, it takes some
time and much work to train your body to forefoot or mid-foot strike, especially because you need stronger feet and calf muscles. Runners should be careful not to develop Achilles tendonitis when they switch from heel striking to forefoot or mid-foot striking.

Steve Nearman has been a running writer for 30 years and is the event director and founder of the Woodrow Wilson Bridge Half Marathon in Alexandria, VA.