If you’ve been worried your healthy exercise routine would erase important memories — or if you still haven’t begun exercising, period — never fear. Rebutting previous research that claimed exercise could wipe away memories, a new study published Wednesday reports that this is not the case.

Whew. So put on those running shoes and get going!

Related: No Exercise? You’re Gambling with Your Life

A research paper published in 2014 claimed that running triggered memory loss in some rodents by boosting the birth of new brain cells. The study suggested that making new brain cells rejiggered memory circuits, making it harder for small animals to remember what they had previously learned.

Neuroscientist Paul Frankland from the Hospital for Sick Children in Toronto — who conducted the 2014 study — reported this phenomenon in mice, guinea pigs, and degus (rodents native to Chile and related to guinea pigs and chinchillas).

Frankland and his colleagues also reported that brain cell genesis wiped out a certain type of memory — fearful memories, to be exact. In a subsequent study, Frankland’s team said they found similar results with spatial memories, as Science News reported. After exercising, mice had trouble remembering the location of a hidden platform in a water maze, the team reported in February in Nature Communications.

Brand new research by Texas A&M College of Medicine, however, has found that exercise causes more new neurons to be formed in a critical brain region, and that these new neurons do not cause the individual to forget old memories. The findings were just published in the Journal of Neuroscience.

Exercise causes more new neurons to be formed in a critical brain region.

Maybe rats are the exception, said Frankland of the new research, “but I’m not convinced,” he told Science News.

Exercise is known for its cognitive benefits, which are thought to occur because it causes neurogenesis — the creation of new neurons — in the hippocampus, a key brain region for learning, memory and mood regulation. Frankland’s two research studies were a surprise to the neurologic research community and to those committed to exercise.

Who do you think would win the Presidency?

By completing the poll, you agree to receive emails from LifeZette, occasional offers from our partners and that you've read and agree to our privacy policy and legal statement.

Texas A & M researcher Ashok Shetty and his colleagues appear to have confirmed the opposite of Frankland’s findings. Whether rats exercised or not, four weeks after learning how to find a hidden platform the rats seemed to remember the location perfectly.

“It is well-known that exercise improves mood, improves cognitive ability, intelligence, and the ability for making new memories, too,” lead researcher Dr. Ashock Shetty told LifeZette. “Old memories are not erased through exercise, and its important for people who exercise on a daily basis to know this.”

He added, “Any memory that has been well-fixed in the brain is not removed. The previous studies used mice, but a rat’s biology is closer to a human’s, and rats are very well-suited for memory tests.”

“Cherished memories and memories that have been consolidated very well will not be lost by exercising,” Shetty noted.

 

Related: A Nurse’s Warning: Our Kids Need Exercise

How was all of this tested? Using a water maze similar to Frankland’s, Shetty’s team taught two groups of rats to find a hidden platform in eight training sessions over eight days, Science News reported. Then, rats in one group exercised on a running wheel. Four weeks later, rats in both groups performed the same in the maze test — despite the fact that the running rats had 1.5 to 2 times more new brain cells in the hippocampus.

These results and other memory tests “clearly showed that exercise did not interfere with memory recall,” Shetty said in his findings. It’s likely that exercise doesn’t harm human memories either, he also noted.

Frankland said maybe Shetty’s rats just learned the water maze too well. Shetty’s team trained their rodents for longer than Frankland’s team did — perhaps etching memories more deeply in the brain.

“The stronger the memory is, the harder it is going to be to erase it,” Frankland said.