Running Is the Killer App of the Human Body

Modern cavemen are all the rage. Paleo-eating guys with beards trying to reconnect with their inner savage. But are they missing the most important step?

Modern cavemen are all the rage. Paleo-eating guys with beards trying to reconnect with their inner savage. But are they missing the most important step?

Why We Evolve

If you really want to be an urban caveman, you need to run. Human evolution has taken us from monkey to man over the space of about six million years. Our last shared ancestor is the chimp, roughly that long ago, and since then we’ve changed quite a bit.

The thing about evolution is that adaptations never occur on a whim, but always in response to a survival situation. In other words, we only evolved as a species when one of our kids was a little bit different, and it was that difference that allowed him or her to eat better, and therefore to have more kids.

The Killer App Theory

Before I get into all the reasons why we evolved as runners, let me explain why it’s important to honor this aspect of our lives. Dan John has this great expression about fitness tools and killer apps. Basically, the Killer App Theory states that every tool has something it is best used for. A barbell’s killer application is maximal strength work in the big lifts like squat, bench, deadlift, and the Olympic lifts. The kettlebell’s killer app is in ballistic exercises like the swing, snatch, and jerk done for a reasonably high number of reps.

If you ever find yourself training with something like a Shake Weight – which has no killer app, no single thing it helps you do better than any other tool – then you can throw it away. This makes purchase choices for your home gym very easy when you realize there’s really only the need for half a dozen pieces of equipment.

It would make little sense, for example, to use a kettlebell to try to get as strong as you could with a barbell, while attempting to do barbell complexes for fitness. The result would be so much better if you’d use the bar for strength and then condition with the kettlebell.

Running Improves Everything

But then we run into the next problem. Somewhere along our evolution, we got sick of being outside. Maybe that’s an inbuilt fear from early man needing to shelter from hungry predators, but as we’ve become more evolved, we’ve stopped going outside.

Along the way we invented gyms and came up with a bunch of ways to “get fitter” that didn’t require moving. We came up with “lift weights faster” as our means of getting cardiovascular conditioning. While circuit-type training can have a beneficial increase on fitness, it will never improve our fitness as much as running will.

Running is a strange fitness activity in that it will improve all other fitness. If you want to have better fitness for grappling or boxing, then you can run, as fighters have done for centuries. But the reverse can’t be said. Grappling and boxing will not improve your running. Running will improve your rowing and cycling, too – but not the other way around. (For evidence see Lance Armstrong’s times from when he decided to run a marathon.)

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And looking at our concept of the killer app, it’s pretty obvious that when you look at the human body we were designed for one thing in mind. Don’t believe me? Consider the following:


Humans are highly efficient walkers. This came in response to needing to forage for food over a larger area than our chimp cousins. The advantage of bipedalism is that it exposes less of the body to solar radiation (only the tops of the head and shoulders versus the entire back and head in other primates). That allowed early man to travel distances of up to 15km daily looking for food, while chimps will average only 2km.

Bipedalism also exposes more of the body to cooler air currents that exist over one meter off the ground. Along with sweating – the rate we sweat is an exclusively human trait – this allows us to cool ourselves effectively with a combination of evaporation and convection.

Long Legs

Unlike chimps who have long arms and short legs, which make for effective climbing, we have much longer legs. This allows us to cover long distances efficiently. So efficiently, in fact, that human locomotion is the ultimate in energy conservation. It takes the exact same number of calories to cover a given distance running, no matter how fast you run. Chimps, on the other hand, with their ambling, knuckle-shuffling run use up to four times the energy to move quickly.

Energy Conservation

Within our legs are some amazing mechanical devices that allow us to be so much more economical than other primates. Simply running at ninety steps per minute increases leg stiffness, and therefore running economy, by 300%. This is accomplished through a combination of the arch of our foot and the Achilles – structures that our monkey forefathers didn’t have. (While primates have an Achilles it is far shorter than human Achilles – 2cm versus 10cm.)

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Big Butts

Sir Mix-a-lot was right, at least when it comes to an evolutionary standpoint. Chimps and other apes do not share our large prominent glutes. The glutes really only activate when running, jumping, or moving up inclined surfaces, being almost completely inactive when at standing or walking. Not only does the butt provide much of the power for running, but it also has a role in stabilizing the upper body during running (and thus also aids in stability during throwing, too – another trait we would have benefitted from during our hunter gatherer years).

This ability to resist rotation is one that our primate ancestors don’t share, another compelling piece of evidence to show that we were well on our way to becoming runners. During running, but not when walking, the center of balance changes from one side of the body to the other as we land on alternate feet on each stride. (We also have a unique-to-us ligament called the nuchal ligament that stabilizes the head while running. As they cannot truly run, neither chimps nor apes possess this ligament.)

Running Is the Killer App of the Human Body

Looking at all the evolutionary changes we’ve gone through, from a completely upright stance to sweating to the energy conserving nature of our gait, it’s pretty obvious that the ability to run far for long periods of time was a necessary adaptation that allowed early humans to gain access to higher quality food. It’s the killer app of the body.

So if we’re looking for the best way to gain fitness, as well as reclaim the most integral of human movements, you have to look to running. I realize that many people can’t run due to injury or dysfunction, but for everyone else trying to get fitter and wondering why “lifting weights faster” doesn’t seem to be doing much for them, I suggest running.

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Running is literally the thing that separated us from the pack from an evolutionary standpoint and allowed us to become the apex predator of the planet. It allowed us access to higher quality food sources at times of the day when other predators were lying in the shade avoiding the heat (because they walked on all fours and couldn’t sweat).

Ignoring running in your own training (provided you are capable of doing so) is ignoring the very essence of humanity and six million years of evolution. This doesn’t mean you need to go and chase down an antelope or run a marathon tomorrow, but if general fitness is your goal then running should be in your plan.

Photo 1 “Fingers crossed” by Niklas Hellerstedt Attribution-NonCommercial License.

Photo 2 “Vancouver Sun Run 2006” by kris krüg Attribution-NonCommercial-ShareAlike License.

Photo 3 “Foulées Halluinoises – 10,000 m Men Run” by Stephane Vervalle Attribution-NonCommercial-ShareAlike License.

Photo 4 “Running Shoes” by Josiah Mackenzie Attribution-NonCommercial License.