For something like that routine, walking is amazingly complex. Biomechanists divide a step into several stages: The first is to hit the ground, when your heel hits the floor. Next is the single support phase, when you balance on that leg. Then you tiptoe to take off and your legs go into forward swing.
All this contains a mystery. Researchers have long observed that when we walk, our planted foot bounces twice before moving on to the next step. That is, the knee is bent and extended once when the foot first touches down, then again just before take-off. That first bounce helps our feet absorb the impact of our weight as we hit the ground. But the function of the second bounce, a feature that characterizes human gait, has never been clear.
in one Physical Assessment E paper published last month, scientists at the University of Munich may have found the answer. By modeling the physical forces that drive our double bounce, they deduced that it’s an energy-saving technique for a species that has long prioritized endurance over speed—which could are clues as to why humans evolved with such an odd gait. Now, they think their model could help improve the designs of prosthetics and robotics, possibly even helping to better understand the evolutionary pressures our ancestors faced.
Daniel Renjewski, a mechanical engineer who led the study, said: “The foot is the key factor here. Quite frankly, the human foot is a strange thing in the animal kingdom. Humans have a 90-degree angle between their feet and legs, he continued, but very few other animals do. That means most animals walk on tiptoes or tiptoes, while we walk on heels. The human foot is also relatively flat and our legs are quite heavy, both of which make standing upright while pushing the body forward a mechanical challenge.
Susanne Lipfert, a sports scientist from the University of Munich who co-authored the study, said our double bounce walking pattern is different from the single bouncing walk we do when running, which is an active movement. weak in the air. While walking, the foot is kept stationary for up to 70 percent of the step cycle to help us balance at a slower pace. But that comes with a trade-off: less time to push yourself forward. On the contrary, it means your body has to work harder when walking to cycle the foot into its next step. “At first glance, it seems odd to aim for a gait where you only have very little time to swing your legs forward,” says Renjewski, given how heavy our legs are: Mass Bigger requires more power.
So, with all these challenges, how does humanity manage to overcome? For years, even our mechanical understanding of how we walk was limited, because trying to model the action of all the muscles, tendons, and joints of the lower body at any given time. any time is a difficult if not impossible task. However, Renjewski’s team discovered that the human gait can be reduced to a single equation, based on how the foot behaves during the double bounce.
To build their model, the researchers reduced the foot system to just four joints in the hip, knee, ankle, and toe. Using data Lipfert collected as a graduate student—information about the forces and joint position of 21 people videotaped while walking on a treadmill—they attempted to describe the stride from heel to toe as if it were a simple object rolling on the ground. That movement is easier to understand than trying to explain the entire anatomy of the foot.
