by G. John Mullen, DPT 2011 | firstname.lastname@example.org
Running and walking are pre-programmed in the humans. At birth, a child will lay on their back and mimic stepping motions with the lower extremities as a result of a central pattern generator in the spinal cord providing signals to step. More interesting, this pre-programming is noted in many mammals. Cats with a spinal cord transsection (i.e. cut in half) are able to step when their body weight is supported. These discoveries have lead to new treatment and further research into body weight supported training following a spinal cord injury.
Once upon a time, before the invention of grocery stores, humans had to hunt. While hunting, humans were often much slower than their prey (for example, buffalo, deer, kangaroo, etc.) forcing them to rely on their elite anatomy and physiology to take down a meal. Humans have large gluteal (backside) muscles, long legs and a bipedal gait along with significant endurance capacity and the ability to sweat, all attributes that are beneficial for distance running. Distance running is an omnipresent past time in America and, as a result, tons of resources have been dedicated to the scientific investigation of the sport. You may have heard about the Harvard research study which suggests that wearing running shoes is as dangerous as running with a tack in your shoe. We would also predict that most runners have considered the barefoot approach due to the proposed benefits (decreased injury rate, faster times, return to “natural running/gait”, decrease equipment and cost of shoes) and if Harvard thinks it is beneficial, doesn’t that mean it is? “Natural gait” is an ambiguous term but, if forced to describe it we would as such: the unconscious manner in which every land animal runs without an external device. The efficacy of this new (or rather old) approach to running is highly debated by biomechanists, podiatrists, physical therapists, runners, triathletes, moms, dads…and little has been absolved. This article will discuss the proven facts about barefoot running, the potential benefits and a proper approach to joining the barefoot running brigade.
First and foremost, all of the potential benefits of barefoot running are anecdotal, subjective and thus debatable as their is no proven scientific evidence showing that decreased injury or faster running times are the result of habitual barefoot running. These claims are assumptions based on scientific findings which analyze the position of the foot while landing. Yeah, it’s a bit of a stretch. The Harvard paper mentioned above as well as others note that barefoot running changes the landing position of the foot from a heel-strike landing to a forefoot landing (meaning you land on the balls of your feet). This shift in landing will alter the torque and demand at the ankle and knee joint. It is estimated that 30% of runners are injured annually, suggesting heel-strike landing is causing too much impact during landing and the knee joint is receiving the bulk of this force as the ground reaction force is attenuated at the knee. Forefoot running changes the torque at the ankle, repositioning the demand to the ankle and calf. This landing technique decreases the amount of passive structures (joints, ligaments) needed for landing and relies on active structures (muscles, tendons) most notably in the calves and ankle. This shift seems to suggest that barefoot running will decrease the risk of injury as it is more biomechanically correct to rely on your muscles to absorb impact as they are more adaptable to force than passive structures. This shift, theoretically, will decrease running injuries, most notably in the knee. What about the promise of increased speed? To allow for a heel-strike landing, current running shoes have large heels to provide cushion during the landing, decreasing the ground reaction force, but increasing the demand by increasing the lever arm. Running with a heel-strike landing, as seen in people wearing running shoes, leads to a spike in force as the heel hits the ground followed by a quick drop in force suggesting a decrease in acceleration and a decrease in speed. Barefoot runners have a constant force during their landing suggesting faster running or rather running without cyclical increasing and decreasing speed.
Stat Fact: Approximately 75% of shoe runners have a heel-strike landing.
Real World Application
All of the research from the Harvard study came from habitual barefoot runners who have been running and walking in this manner for their entire lives. Therefore, their body has adapted to the biomechanical changes noted above. Most Americans have been using running/tennis shoes their entire lives (we still get a kick out of seeing a baby in Nike Air Force Ones or Jordans) and have been trained to running with a heel-strike landing. For this reason, it is hard to directly apply the information in the Harvard study to the common runner who has been heel-striking in their fancy running shoes since breast feeding. As stated, the shift in ground reaction force causes a shift in structures involved during running with and without shoes. As one runs without shoes, the demand on the calf and ankle increases dramatically. Barefoot running greatly increases the demand on the calf muscle (during a forefoot landing the calf contracts during the lowering of the heel followed by a concentric contraction of the calf as the runner pushes off the ground). The side of the calf (the peroneal muscles) will also experience increased demand during the running cycle. Therefore, the claim that barefoot running will decrease injury is a misnomer: barefoot running it will serve to shift running injuries from the knee and shins to the ankles and calves. Many therapists have reported a recent rise in Achilles’ tendonopathies but no published research has shown an increase in these injuries or a decrease in knee and shin injuries (again, all anecdotal). As far as increasing speed, only subjective evidence is available. Some food for thought, however: most Kenyans run with a forefoot strike…just saying.
Stat Fact: Running barefoot is believed to be 5% more energy efficient.
Adapting to Barefoot Running
Once again, all of the data on barefoot running comes from habitual barefoot runners who have learned the proper mechanics and developed the needed strength to accomplish this task through years of training. As for using finger shoes (made by Vibram. Note that Vibram helped fund the research performed at Harvard…i.e. potential conflict of interest) these shoes do allow the same barefoot style running. We would only recommend these shoes if your are running on potentially dangerous surfaces (hot surfaces, dirty/debrided areas, rocks/cracks, etc.). If you are considering trying barefoot running, we recommend you do a few things before beginning. First biomechanically, two general items must be accomplished:
Develop a soft, relaxed landing on the outside part of the ball of your foot (not too much on the toes) then lower your heel down gently. This will decrease the ground reaction force but will increase the demand on the calf and Achilles’ tendon.
Do not over stride; this often leads to the toes being pointed down, increasing the demand on the calf. Over-striding will increase the force requirements of the calf and subsequently increase your risk of injury.
Lastly, one needs to try barefoot running on a hard smooth surface (pavement). This will give the runner an indication of the force through the foot and heel. Barefoot running isn’t for everyone. If it feels unnatural or hurts, do not try to push it. Everyone has different running mechanics, muscle strength and muscle length, the combination of which determines your personal running style. Put simply, barefoot running is not for everyone!
If the trial barefoot run is positive and you want to implement this running philosophy, be careful not to overdue it in the beginning. The muscles in your legs are not prepared for the increased demand you are placing on them and the risk of injury will increase. Here is an example of a safe transition plan to the barefoot running style:
Start by walking around barefoot frequently (around the house, walking the dog, etc.). This will help prepare your legs for the increased strength needed. If you use resistance training, add eccentric calf raises and eversion to your repertoire.
Week #1: Run a maximum of a quarter mile to one mile every other day without shoes.
Increase your distance by no more than 10% per week. This amount should be individualized, but 10% is typically on the high end. Remember that if you get injured you will have to take time off and start back at square one. Slow and steady is the way to go.
If you have pain/increased soreness, take a day off! Be smart about adapting any new training program and listen to your body as it is the best indicator of your health.
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2. Lieberman DV, M. Daoud, A. Werbel, W. Running Barefoot: Training Tips.
3. Lieberman D, Venkadesan M, Werbel W, et al. Foot strike patterns and collision forces in habitually barefoot versus shod runners. Nature. Jan 2010;463(7280):531-535.
4. Tucker RD, J. The Science of Sport: Running Barefoot vs. Shoes. 2010.