As temperatures have reached record levels around the world, a new study suggests that dehydration causes thinking problems. Researchers found that athletes who lost fluid equal to 2 percent their weight took a hit to their cognition.
The study published in the journal Medicine & Science in Sports & Exercise, said that even a mild to moderate level of dehydration- the loss of 2 pounds for someone who weighs 100 pounds and four pounds for someone weighing 200 - led to attention problems and impaired decision making, Reuters reported.
In particular, dehydration led to impairment in tasks requiring attention, motor coordination, and so-called executive function, which includes things like map recognition, grammatical reasoning, mental math, and proofreading, for example.
Study coauthor Mindy Millard-Stafford, a professor in the school of biological sciences and director of the physiology lab at the Georgia Institute of Technology, said: “We’ve known that physical performance suffers at a threshold of 2 percent of body mass, particularly when it’s from exercise in a warm environment.”
While the effects weren’t huge at 2 percent, they increased with increasing dehydration, Millard-Stafford added.
The researchers looked at 33 studies involving a total of 413 adults. Participants lost fluids amounting to 1 to 6 percent of their body mass either through exercise alone, exercise coupled with heat, heat alone or fluid restriction.
Dr. Ronald Roth, a professor of emergency medicine at the University of Pittsburgh School of Medicine, said: “I think this reinforces something we thought was true. The big picture here is that the more dehydrated you are the less sharp you are.”
It can be hard to diagnose dehydration, so it’s important for individual athletes to keep track of how much fluid they’re taking in and how much they’ve lost, Roth said. Still, certain symptoms should be reminders that it’s time to take in more fluid: fatigue, muscle weakness, decreased urine output, confusion.
Roth warns against overdoing things and taking in too much water, which can damage minerals’ balance in the body. “It’s important to know the right water balance. You need to know that you can have not just too little but also too much,” Millard-Stafford noted.
Millard-Stafford explained that the color of your urine is a simple way of monitoring your fluid levels: If it’s very, very clear, then you are probably drinking far more than necessary, but if it’s dark gold that may mean the kidneys need a little more reserve to keep the balance where it needs to be.
