Amazingly, scientists who study these women and measure their oxygen consumption have identified that, in addition to their great strength, they are likely the most efficient "movers" on the planet. In other words, the researchers found, "Kikuyu women could carry loads of up to 20 percent of their body weight without increasing their rate of energy consumption." These women carried loads up to 20 percent of their bodyweight, strapped to their foreheads, and their rate of energy consumption did not rise, at all!
Think about that for a moment because it really is quite amazing, and it presents a rich opportunity for us to learn from them. The Kikuyu women can teach us how we need to train in order to have a similar level of efficiency.
Clearly, the Kikuyu women are extraordinarily strong. However, there are two reasons why they are able to handle these loads without an increase in how much energy they use to move along the ground.
1. The Kikuyu women have excellent posture. There's no way these women could carry these loads and not sustain injury in any of a number of places, including their necks, if they had the typical "forward head" carriage that we routinely see during the gait analyses we perform on runners who visit the Pursuit Athletic Performance gait lab I co-founded.
These women are more efficient, in part, because less energy is used to maintain head position directly over the shoulders and spine. Interestingly, it was reported in Running Research News that the great Ethiopian marathoner Abebe Bikila, (the most well known and first of the barefooted marathoners, by the way) said one of the keys to his success was learning to balance his head properly on top of his body.
2. One of the important aspects that became obvious to researchers who looked at the Kikuyu was that the amount of vertical oscillation (up and down movement of their bodies through the gait cycle) as they moved was virtually non-existent. In other words, as they carried the heavy loads on their backs, they did so with the least possible up and down movement with each stride they took.
However, the greatest key to their efficiency according to the researchers, was not related to genetics or some crazy phenomenon unique to these women—it was what was happening (or not happening) at their feet and hips.
What Is the Perfect Pendulum?
Think again of that pendulum for a moment. The "top" of our running stride during the mid-stance phase—one foot under our center of mass while the other is in mid-swing—is when our center of mass reaches its greatest height and, thus, when potential energy begins to drop. To put it another way, the researchers noticed that at this particular point in the Kikuyus' stride, there was absolutely no pause or loss of momentum. In brief, the Kikuyu woman demonstrated:
- No added deceleration, which would cause greater muscular stress and fatigue due to the forces of gravity and ground reaction (3 to 4 x body weight), and lead to greater risk of injury.
- No loss of energy or momentum, which means less muscle energy would be needed to "restart" forward momentum.
- No increase in unnecessary energy expenditure due to braking or a lack of stability or weakness.
- No energy leakage due to too much motion to stabilize the body (think of standing on a BOSU—that's what happens when you aren't stable).
In summary, a near perfect pendulum—continuous motion all the way through the top of the stride—leads to less energy needed to continue momentum and movement, or to get back up to speed.
Why Inefficiencies Make Runners Slower
So, what does this mean for all of us trying to reduce injury risk and get faster? There are a couple of very important takeaways from this story of the Kikuyu.