Running may be the quintessential human activity. Eons ago, our ancestors ran to stay alive, whether by escaping from predators or by chasing prey over long distances. Persistence hunting, in which man chases down beast on foot over distances as long as twenty miles until the animal is too exhausted to continue, may have been the earliest form of human hunting. Today, it is practiced by only a handful of peoples across the globe.

Most modern humans run not to eat, but to exercise. Picturesque plains and African scrub have been replaced by parkways and city sidewalks. Runners embark on their journeys armed with iPods and earbuds rather than spears. And before they jog out the door, many of them wonder, "What is the best way to run?"

There are a number of ways to explore this question, and that's a big reason why science has yet to provide a clear answer. Let's start by looking down at our feet and asking, "Is it better to run barefoot or with shoes?"

In this day and age, most skeptics might understandably ask how this is even a question. After all, shoes cushion our feet and guard against the rigors of the road, like rocks, trash, and cracks. Moreover, the barefoot notion seems to be a clear offshoot of the naturalistic fallacy, as many proponents argue that since our ancestors ran barefoot, it must be better.

In reality, the barefoot discussion is not about shoes at all, but about how we use our feet. The most prominent scientist in support of barefoot running, Harvard paleoanthropologist Dan Lieberman, contends that the barefoot style tends to make runners land more on the front or middle of the foot, rather than the heel. This, he writes on his Harvard website, is the real key.

"In heel striking, the collision of the heel with the ground generates a significant... large force. This force sends a shock wave up through the body via the skeletal system. In forefoot striking, the collision of the forefoot with the ground generates a very minimal impact force... Therefore, quite simply, a runner can avoid experiencing the large impact force by forefoot striking properly."

Lieberman is not the only scientist espousing this view. As an international team of scientists reported in a 2014 issue of the Journal of Sport and Health Science:

"From a mechanical perspective, the two most important anatomical springs in the human leg are the Achilles tendon and the plantar arch; together, these structures store and return roughly half of the potential and kinetic energy lost each step during running. These anatomical springs are most effective when runners land on the middle or front of the foot, allowing the Achilles tendon and plantar arch to stretch as the foot is loaded during early stance phase."

Lieberman hypothesizes that this more economical style of running may reduce injury rates. Scientific research addressing that notion is now starting to trickle in. One study examining injuries among cross-country runners found similar rates of traumatic injury between front- and rear foot-strikers, but significantly higher rates of repetitive stress injury among rear strikers. Another focusing only on shod versus barefoot runners found no difference in injury rates.

With a paucity of studies performed thus far, the jury is still out on Lieberman's hypothesis. It may be that the barefoot style will only shift the location of running injuries, rather than reduce the incidence. Forefoot and mid-foot striking puts more pressure on the ankle, while rear-foot running puts more pressure on the knees and upper leg muscles.

Most casual or inexperienced runners typically strike with their heels first, as has been encouraged by shoe design over the years. But now, more and more shoes are being designed with a mid-foot strike in mind, so one doesn't need to go barefoot to try out a different style of running. Switching your running style shouldn't be done too rapidly, however. Runners accustomed to rear-striking will be adapted to running in that fashion, and switching too quickly will almost certainly result in injury. Luckily, science-based guides exist that can help runners navigate the process safely.

If you're not interested in changing your foot-strike habits, there is one simple adjustment that seems to universally benefit all long-distance runners: take more strides. A systematic review published to the journal Sports Health in 2012 found consistent evidence in the scientific literature that taking more and shorter strides alleviated pressure at the hip, knee, and ankle joints.

While most humans no longer need to literally run for their lives, running is one of the easiest forms of exercise to extend lives. On that point, science is nearly unanimous.

(Images: AP, Rothschild via S&C Journal)