A "lazy" gene may very well exist, according to a new study from the University of Missouri.
For the new study, published in the American Journal of Physiology this month, scientists at the university bred 10 generations of rats based on their penchant for nightly exercise. The breeding created one lineage of lazy rats and one lineage of go-getters,
The Washington Post reported.
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Scientists placed a group of rats in cages with running wheels for six days and recorded how much time they spent on it.
The top 26 exercisers were then separated from the 26 most indolent, and each group was bred separately. Researchers repeated this process 10 times, separating the "motivated" rats from the "lazy" ones in each generation.
After 10 rounds, the academics found that the rats in the "super runners" lineage were 10 times more likely to run than those of the "couch potato" family.
"We have shown that it is possible to be genetically predisposed to being lazy," researcher Frank Booth said.
Scientists examined the body composition for both groups of rats.
"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, a post-doctoral fellow at the University of Missouri's College of Veterinary Medicine. "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 findings confirm and expand on a study from 2011, in which scientists identified two genes in mice that appear to be crucial to exercise motivation. When those two genes are turned off, the mice are drastically affected.
"While the normal mice could run for miles, those without the genes in their muscle could only run the same distance as down the hall and back. It was remarkable," said Gregory Steinberg of McMaster University at the time.
Both studies offer promising perspectives in understanding the fight against obesity if the rats' biology works in the same way as humans' genetics do, the research team said.
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