Do Your Genes Make You Lazy?

Brett Smith for redOrbit.com – Your Universe Online
If you´ve ever had a hard time getting motivated to go to the gym or get off the couch and head outside for a jog, it could be your genetics.
According to a new study in the American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, a team of Missouri researchers were able to selectively breed rats that had either an active or lazy disposition.
“We have shown that it is possible to be genetically predisposed to being lazy,” said study co-author Frank Booth of the University of Missouri in a statement. “This could be an important step in identifying additional causes for obesity in humans, especially considering dramatic increases in childhood obesity in the United States.
“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 added.
To select for one of the two dispositions, the team put rats in enclosures with exercise wheels and recorded how much each rat willingly ran on their wheel over the course of a six-day period. The researchers then selectively bred the top 26 most active with each other and did the same for the 26 laziest. After 10 generations of breeding, they found the more active rats chose to run 10 times more than the descendents of “lazy” rats.
The researchers also performed a biological and genetic analysis of each line of rats. They examined the levels of mitochondria in the rats´ muscle cells, compared body types, and conducted an RNA analysis 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 study co-author Michael Roberts, Professor of Animal Science and Joint Professor of Biochemistry at MU.
“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.”
The results of the study could have a significant impact, especially for the 97 percent of American adults studies show get less than 30 minutes of exercise a day — the minimum recommended by federal guidelines.
According to the researchers, they plan on continuing their work to identify the effects each gene has on the motivation to exercise.