Can't get off the couch? Blame your genes: new U.S. research suggests certain genetic traits may predispose people to being more or less motivated to being active.
University of Missouri researchers selectively bred rats that exhibited traits of either extreme activity or extreme laziness. While humans aren't rats, the scientists say that the rats indicate that genetics could play a role in exercise motivation in humans, too.
"We have shown that it is possible to be genetically predisposed to being lazy," said researcher Frank Booth. "This could be an important step in identifying additional causes for obesity in humans...It would be very useful to know if a person is genetically predisposed to having a lack of motivation to exercise, because that could potentially make them more likely to grow obese."
Booth and the team put rats in cages with running wheels and measured how much each rat willingly ran on its wheel during a six-day period. They then bred the top 26 runners with each other and bred the 26 rats that ran the least with each other. The scientists repeated this process through 10 generations and found that the line of running rats chose to run 10 times more than the line of "lazy" rats.
Once the researchers created their "super runner" and "couch potato" rats, they studied the levels of mitochondria in muscle cells, compared body composition and conducted genetic evaluations through RNA deep sequencing of each rat.
"While we found minor differences in the body composition and levels of mitochondria in muscle cells of the rats, the most important thing we identified were the genetic differences between the two lines of rats," said researcher Michael Roberts. "Out of more than 17,000 different genes in one part of the brain, we identified 36 genes that may play a role in predisposition to physical activity motivation."