The Harvard researchers continued in Nature:"Here we show that habitually barefoot endurance 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 protect the feet and lower limbs from some of the impact-related injuries now experienced by a high percentage of runners."This may explain how marathon runners in Kenya are able to run great distances barefoot with virtually no pain or injuries. Likewise, research reviewed by Michael Warburton, a physical therapist in Australia, revealed:3
- Running-related chronic injuries to bone and connective tissue in the legs are rare in developing countries, where most people are habitually barefooted
- Where barefoot and shod populations co-exist, as in Haiti, injury rates of the lower extremity are substantially higher in the shod population
- Wearing footwear actually increases the likelihood of ankle sprains, one of the most common sports injuries, because it either decreases your awareness of foot position or increases the twisting torque on your ankle during a stumble
- One of the most common chronic injuries in runners, planter fasciitis (an inflammation of the ligament running along the sole of your foot), is rare in barefoot populations
- Running in bare feet reduces oxygen consumption by a few percent
Grounding: The Overlooked Benefit of Going Barefoot
While much of the debate between the barefoot and the shoed-foot focuses on the potential for injury, another often overlooked aspect is grounding. The technique of grounding, also known as earthing, is simple: you walk barefoot to "ground" with the Earth. The scientific theory behind the health benefits seen from this simple practice is that your body absorbs negative electrons from the Earth through the soles of your feet.The Earth is negatively charged, so when you ground, you're connecting your body to a negatively charged supply of energy. And since the Earth has a greater negative charge than your body, you end up absorbing electrons from it. The grounding effect is, in my understanding, one of the most potent antioxidants we know of and may have an anti-inflammatory effect on your body. As written in the Journal of Alternative and Complementary Medicine:4"It is well established, though not widely known, that the surface of the earth possesses a limitless and continuously renewed supply of free or mobile electrons as a consequence of a global atmospheric electron circuit. Wearing shoes with insulating soles and/or sleeping in beds that are isolated from the electrical ground plane of the earth have disconnected most people from the earth's electrical rhythms and free electrons.… A previous study demonstrated that connecting the human body to the earth during sleep (earthing) normalizes the daily cortisol rhythm and improves sleep. A variety of other benefits were reported, including reductions in pain and inflammation. Subsequent studies have confirmed these earlier findings and documented virtually immediate physiologic and clinical effects of grounding or earthing the body."Unfortunately, few people ever walk barefoot anymore to experience the benefits of grounding. But it is very plausible that some of the people who have converted to barefoot running are experiencing benefits not only from the lack of shoes, but also from the increased connection to the Earth.