The body: efficient or just damn lazy?

Have you ever been branded as lazy for taking the shortest walking path, choosing the lift over the stairs or opting to sit rather then stand? Pure sluggishness might not be to blame according to a recent study. The tendency to carry out tasks in the least effortful way is because humans are physiologically wired to expend the least amount of energy possible. Put simply, we are wired for laziness.

Researchers from Simon Fraser University in Canada have discovered that the human nervous system is extraordinarily adept in changing the way we move in order to disburse less energy. For example, people often freely change the way they walk to conserve small amounts of energy.

Lead researcher Max Donelan explains that even within a well-established movement like walking, the body’s nervous system subconsciously monitors energy use and continually readjusts movement patterns, constantly seeking to use less energy. Donelan concludes that this provides a physiological explanation for laziness.

The researchers were compelled to understand why people move the way that they do, and to learn to what extent our bodies adapt movement based on physiological input. To answer this question, the researchers fitted people with a robotic exoskeleton that allowed them to discourage the participants from walking in their usual way. By making a person’s natural way of walking more difficult, the researchers were able to test whether they could sense and optimise the cost associated with their movements.

The results showed that, within minutes, the participants changed the frequency of their steps in order to carry out a new movement that expended less energy. The researchers found that the body adapted its movement even when the energy saving was less than 5 per cent. This means that the energetic costs of our activities are not simply an outcome of our movements, they actually play a key role in continuously shaping them.

According to Donelan, this finding is consistent with the ingrained sense that most of us have to carry out tasks in the least effortful way. It’s our physiological nature. The challenge for an increasingly obese world is to either go against this natural behaviour – at least during bouts of physical activity – or to reduce an excessive energy intake that is disproportionate to our energy output.

Source: Current Biology