Want to Increase Brain Oxygenation? Locomotion May Be Key

Sometimes, it takes neuroscientists much longer than one might expect to substantiate everyday observations that seem like common sense.

For example, during continuous moderate-to-vigorous physical activity (MVPA) or high-intensity interval training (HIIT), it feels like all the "huffing and puffing" that accompanies a cardio workout plays a direct role in delivering highly oxygenated blood to every part of your body and brain.

Many joggers use locomotion to boost brainpower. Runners often describe "cobwebs clearing" from their minds as the blood and oxygen start pumping through their brain with increased robustness and velocity during a run.

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Commonplace anecdotal evidence suggests that there's a correlation between cardiovascular exercise, respiration, and well-oxygenated blood flow to the brain. That said, the link between aerobic exercise and increased cerebral blood flow (CBF) that may seem like an obvious "no brainer" to most gym-goers is surprisingly complex and challenging for researchers to monitor in a laboratory setting.

Therefore, as someone who's dedicated my adult life to using science-based evidence to motivate people to seek daily exercise, I was excited to read a science news headline this morning and share the latest findings on exercise and brain oxygenation with you.

Even though this study was conducted on mice, hopefully the new paper, "Cerebral Oxygenation During Locomotion Is Modulated by Respiration," will inspire you to make "huffing and puffing" during an aerobic workout a bigger part of your daily routine.

These new findings, on a link between aerobic exercise and oxygenated blood flow to the brain, were published on Dec. 4 in the journal Nature Communications.

The main focus of this study was to explore how exercise affects brain oxygen levels. The scientists monitored the respiration, cerebral blood flow, brain oxygenation, and neural activity of mice who were given access to a treadmill in their laboratory habitat and could choose to stay sedentary or voluntarily walk/run.

The authors begin their paper by stating:

"In the brain, increased neural activity is correlated with increases of cerebral blood flow and tissue oxygenation. However, how cerebral oxygen dynamics are controlled in [mammals] remains unclear. As exercise is known to have a positive effect on brain health, a better understanding of the basic brain physiology accompanying these behaviors can give insight into how exercise can improve brain function."

Contrary to the long-held assumption that the blood of living mammals is continually saturated with oxygen, the researchers found that increased respiration during locomotion packs more oxygen into the hemoglobin of mammalian blood.

The trickiest part of measuring brain oxygenation is that, typically, these studies are conducted non-invasively in humans or on anesthetized animals. What makes this new study unique is that the researchers were able to measure the extent that locomotion-evoked cerebral oxygenation varied while mice were voluntarily walking or running on a spherical treadmill compared to when they were sedentary. To measure oxygen levels of awake mice during locomotion, the researchers used methods such as two-photon phosphorescence and laser Doppler flowmetry.

Patrick Drew, who is an associate professor of neural engineering and neurosurgery as well as the associate director of the Penn State Neuroscience Institute, is the senior author of this paper.

"We know that people change breathing patterns when doing cognitive tasks," Drew said in a news release. "In fact, respiration phase locks to the task at hand. In the brain, increases in neural activity usually are accompanied by increases in blood flow."

The researchers were surprised by their discovery that locomotion, respiration, and cerebral oxygenation go hand in hand.

"We predicted that brain oxygenation would depend on neural activity and blood flow," first author Qingguang Zhang, a postdoctoral fellow in engineering science and mechanics at Penn State, said in a news release. "We expected the oxygenation would drop in the brain's frontal cortex if blood flow decreased. That was what we thought would happen, but then we realized it was the respiration that was keeping the oxygenation up."

"The only way that could happen would be if exercise was causing the blood to carry more oxygen," Zhang added.

If you need another reason to exercise more and sit less, remember: Locomotion increases respiration and appears to provide a dynamic pathway for boosting cerebral oxygenation and optimizing cortical functions.