Humans and our recent ancestors have been accomplished endurance runners for more than a million years (Bramble and Lieberman, 2004). Our endurance running abilities may have evolved to enable our ancestors to engage in persistence hunting long before the comparatively recent invention of projectile technologies used for hunting purposes (Carrier, 1984; Lieberman et al., 2009).

Our evolutionary history as runners partly accounts for why aerobic exercise is such a key component of human health. For most people, aerobic exercise involves endurance running, either jogging or playing aerobic sports such as soccer and basketball. Unfortunately, studies suggest that at least 30% of runners get injured every year, and many of these injuries stem from problems that arise in the foot or lower leg (van Gent et al., 2007).

Humans evolved to run 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.

We do not know how early humans ran, but our research (Lieberman et al., 2010) indicates that humans were able to run 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). These kinds of foot strikes differ profoundly from heel striking both in terms of how the body is moving and the resulting forces on the body. Most runners who wear standard running shoes usually heel strike, but our research suggests that most barefoot or minimally shod endurance runners forefoot strike and sometimes midfoot strike. The following pages contain information about how these various strikes differ biomechanically and how they are relevant to how people run.