Why we're wired for laziness

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Those of you who spend hours at the gym with the aim of burning as many calories as possible may be disappointed to learn that all the while your nervous system is subconsciously working against you. Researchers reporting in the Cell Press journal Current Biology on September 10 have found that our nervous systems are remarkably adept in changing the way we move so as to expend the least amount of energy possible. In other words, humans are wired for laziness.

Those of you who spend hours at the gym with the aim of burning as many calories as possible may be disappointed to learn that all the while your nervous system is subconsciously working against you. Researchers reporting in the Cell Press journal Current Biology on September 10 have found that our nervous systems are remarkably adept in changing the way we move so as to expend the least amount of energy possible. In other words, humans are wired for laziness.

The findings, which were made by studying the energetic costs of walking, likely apply to most of our movements, the researchers say.

"We found that people readily change the way they walk--including characteristics of their gait that have been established with millions of steps over the course of their lifetime--to save quite small amounts of energy," says Max Donelan of Simon Fraser University in Canada. "This is completely consistent with the sense that most of us have that we prefer to do things in the least effortful way, like when we choose the shortest walking path, or choose to sit rather than stand. Here we have provided a physiological basis for this laziness by demonstrating that even within a well-rehearsed movement like walking, the nervous system subconsciously monitors energy use and continuously re-optimizes movement patterns in a constant quest to move as cheaply as possible."

There is a bright side to this, lead author Jessica Selinger adds: "Sensing and optimizing energy use that quickly and accurately is an impressive feat on the part of the nervous system. You have to be smart to be that lazy!"

Donelan, Selinger, and their colleagues wanted to understand why people move the way they do, given that there are countless ways to get from point A to point B. This is partly a question of evolution and learning. But, the researchers wanted to know, to what extent can our bodies adapt movement based on real-time physiological inputs?

To find out, the researchers asked people to walk while they wore a robotic exoskeleton. This contraption allowed the researchers to discourage people from walking in their usual way by making it more costly to walk normally than to walk some other way. More specifically, the researchers made it more difficult for participants to swing their legs by putting resistance on the knee during normal walking, whereas the researchers eased this resistance for other ways of walking.

Continue reading at EurekAlert!

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