Feeling too lazy to hit the gym? Blame your brain, say scientists who found that it is naturally wired to prefer lying on the couch.
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.
Researchers from the University of British Columbia (UBC) in Canada studied brain connections to understand this "exercise paradox".
"Conserving energy has been essential for humans' survival, as it allowed us to be more efficient in searching for food and shelter, competing for sexual partners, and avoiding predators," said Matthieu Boisgontier, a postdoctoral researcher in UBC.
"The failure of public policies to counteract the pandemic of physical inactivity may be due to brain processes that have been developed and reinforced across evolution," said Boisgontier, senior author of the study published in the journal Neuropsychologia.
For the study, 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 brains. Participants were generally faster at moving toward active pictures and away from lazy pictures, but brain-activity readouts called electroencephalograms showed that doing the latter required their brains to work harder.
"We knew from previous studies that people are faster at avoiding sedentary behaviours and moving toward active behaviours. The exciting novelty of our study is that it shows this faster avoidance of physical inactivity comes at a cost -- and that is an increased involvement of brain resources," Boisgontier said.
"These results suggest that our brain is innately attracted to sedentary behaviours," he said.
The question now becomes whether people's brains can be re-trained.
"Anything that happens automatically is difficult to inhibit, even if you want to, because you don't know that it is happening. But knowing that it is happening is an important first step," Boisgontier said.
