Hardwired for laziness’ Our brain must work hard to avoid sloth

If getting to the gym seems like a struggle, researchers want you to know this: the struggle is real, and it’s happening inside your brain.

The brain is where Matthieu Boisgontier (KU Leuven / UBC) and his colleagues went looking for answers to what they call the "exercise paradox": for decades, society has encouraged people to be more physically active, yet statistics show that, despite our best intentions, we are actually becoming less active.

Their findings, published in Neuropsychologia, suggest that our brain may simply be wired to prefer lying on the couch.

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Saving energy for survival

"Conserving energy has been essential for humans’ survival. It allowed us to be more efficient in searching for food and shelter, competing for sexual partners, and avoiding predators," explains senior author Matthieu Boisgontier, a postdoctoral researcher at the KU Leuven Department of Movement Sciences and the University of British Columbia.

"The failure of public policies to counteract the pandemic of physical inactivity may thus be due to brain processes that have been developed and reinforced across evolution."

Avatar experiment

For the study, the researchers recruited young adults, sat them in front of a computer, and gave them control of an on-screen avatar.

They then flashed small images, one a time, that depicted either physical activity or physical inactivity. Subjects had to move the avatar as quickly as possible toward the pictures of physical activity and away from the pictures of physical inactivity - and then vice versa.

Meanwhile, electrodes recorded what was happening in their brain.

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This animation shows the task volunteers were asked to perform. An image depicting physical activity or physical inactivity would appear in the middle of the screen. Volunteers had to use keys on their keyboard to move the avatar toward physical activity, or away from physical inactivity, as fast as they could.

Laziness goes easier on the brain

Participants were generally faster at moving toward active pictures and away from lazy pictures, but EEG scans showed that doing the latter required their brain to work harder.

"We knew from previous studies that people are faster at avoiding sedentary behaviours and at moving toward active behaviours. The exciting novelty of our study is that it shows this faster avoidance of physical inactivity comes at a cost: an increased involvement of brain resources," says Boisgontier.

"These results suggest that our brain is innately attracted to sedentary behaviours."

Knowledge is the first step

But we have to careful when interpreting the results, Boisgontier warns: "This is the first study using brain techniques to investigate the exercise paradox. We need more research to strengthen and refine our results. Only then can we start thinking about whether people’s brains can be re-trained."

In the meantime, Boisgontier continues, people should be aware of their propensity toward less physical activity. "Anything that happens automatically is difficult to inhibit because you don’t realise that it’s happening. But knowing that it is happening is an important first step."

Matthieu Boisgontier received funding from the Research Foundation - Flanders (FWO). He led this study with Boris Cheval of the University of Geneva. The international team also included researchers from the University of Oxford and the Université Côte d’Azur.