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Tasks that are mental and physical cause people to fatigue quickly

illustration of a man working at a computer while is brain tires from the effort

Illustration: Division of Research

When people engage in tasks that require both mental and physical effort, their bodies tend to fatigue faster than when they are involved in purely physical tasks, a new study suggests.

Why? Because oxygen in the prefrontal cortex falls to a lower level when both the brain and the body are challenged, the study says.

Ranjana Mehta, an assistant professor at the Texas A&M Health Science Center’s School of Public Health, co-authored the study, which was recently published online in Human Factors: The Journal of the Human Factors and Ergonomics Society.

Mehta conducted the study with her co-author, Psychology Professor Raja Parasuraman at George Mason University in Virginia, to better evaluate the interaction between human fatigue and brain behavior.

“Existing examinations of physical and mental fatigue has been limited to evaluating cardiovascular, muscular and biomechanical changes,” said Mehta. “The purpose of this study was to use simultaneous monitoring of brain and muscle function to examine the impact on the PFC while comparing the changes in brain behavior with traditional measures of fatigue.”