People over on Reddit are once again (see also: why we can’t power trucks with a big magnet) asking the big questions: is it more energy efficient to walk around on giant stilts?
In a post to the “they did the math” subreddit, one Redditor asked the question, after seeing a video of members of the Banna tribe in Ethiopia walking around on long wooden stilts, a traditional method of avoiding animal attack whilst herding cattle. Though that is likely the reason that they first started walking on stilts, today it is done for cultural reasons.
“Stilts-walking is a long-standing cultural tradition among community members,” Further Africa explains. “Unmarried young men are the carriers of this tradition popular during community festivals and rituals. A rule for Banna tribe stilts-walking during a ceremony is painting their bodies in white strips.”
So, is it more efficient? Reddit users were mixed in their opinions, if they offered one at all.
“That’s a complicated kinesiology question, not really a math question,” one user wrote. “Generally if you’re not used to it, almost definitely not. But if you got used to it, maybe? You’d probably have to run some tests on someone who was used to it. Can’t answer it by doing some simple math in a reddit question.”
Fortunately, and surprisingly, scientists have looked into it.
“During the eighteenth and nineteenth centuries, stilts were commonly used in some places in the southwest of France, presumably because ground can be covered faster with stilts than by normal walking,” the researchers wrote, justifying the project. “The research reported here sought to verify this latter point by studying the mechanical and energetic aspects of level walking with stilts.”
The researchers, publishing their study back in 1981, took three healthy young men who used stilts as a hobby, and gave them a set of 1.4 meter-long (4.6 foot-long) stilts to demonstrate, which would “lengthen the shank” by 1 meter (3.3 feet).
In a sports hall, the men were then asked to walk around at their normal speed, slower than their normal speed, faster than their normal speed, and “very much faster” than their usual speed. While this was going on, their pace length and speed were measured, along with their oxygen consumption through use of a mask placed over their face.
Agreeing with previous studies they found that to achieve the same speeds, stilt walkers’ pace was longer and step frequency lower than in usual walking.
“At highest speeds, maximum pace length increased by approximately 30 percent with stilts (1.3 m against 1 m). At the same time, step frequency decreased by 10 percent (2 against 2.2/s),” the team wrote. “The overall result is an increase of the maximum speed ranging from 0.7 to 1.5 km·h⁻¹ [0.4-0.9 miles per hour], comparable to mean speeds observed during long-distance stilt-walking races (10 km·h⁻¹) [6 miles per hour].”
The team had hypothesized that stilt-walking should be more efficient:
“[W]alking energy expenditure is directly related to the vertical oscillations imposed at each step to the body centre of mass. The smaller the oscillation, the lower the expenditure of energy. This oscillation is related to the length of the lower limbs (a), the length of the pace (b), and/or the amplitude of [the vertical displacement of the centre of mass].”
However, upon analyzing the results, they found that the difference was negligible.
“Our experimental data do not support this hypothesis,” they concluded, adding that the difference in efficiency was small.
“We think that such a discrepancy can be explained by the weight of the stilts. Ralston and Lukin have shown [in a previous study] that the effect of foot loading is greater than trunk loading. These authors showed that a loading of 2 kg on each foot increased the metabolic expenditure by about 30 percent over controls. Since each of our stilts weighed 2 kg their results may be applied exactly to our conditions.”
In short, there may be some advantages to using stilts (avoiding animals, seeing over tall people at a concert, making yourself appear more like a clown, etc.) but efficiency-wise, there isn’t much in it.
Source Link: The Latest Internet Debate: Is It More Efficient To Walk Around On Massive Stilts?
