Mild Dehydration Could Mess Up Your Concentration

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iStock

Research has already shown us that enduring a heat wave without air conditioning can impair our mental performance. Now, a new paper reported by NPR shows that not drinking enough water in the summertime can have a similar impact. According to a meta-analysis published in July in the journal Medicine & Science in Sports & Exercise, even mild dehydration can negatively affect cognition.

Mindy Millard-Stafford, director of the Exercise Physiology Laboratory at Georgia Institute of Technology, looked at 33 studies dealing with dehydration. She found that subjects performed worse in a range of areas—including attention, motor coordination, and goal-oriented thinking—when they were slightly dehydrated compared to when they had consumed enough water that day.

She defined mild dehydration as fluid loss equivalent to about 2 percent of body mass. On a hot summer day, reaching this stage can happen surprisingly fast. If you're hiking in the heat, it might take you an hour to become mildly dehydrated, and if you're going on an intense run, it can take just 30 minutes to sweat out 2 percent of your mass.

That level of dehydration isn't too noticeable (you may just start to feel thirsty), but if you have to do something that requires your full attention, it makes a big difference. In one study published last year, female subjects who were 1 percent dehydrated made 12 percent more errors while playing a game that required them to think quickly. (That paper was funded by PepsiCo, which sells bottled-water brands like Aquafina and Propel, but the researchers designed the study independently, according to NPR.)

Luckily, the brain fog that comes with dehydration has a simple antidote: a glass of water. The biggest roadblock keeping you from staying hydrated may be your inability to recognize dehydration in the first place. To see if you're getting enough water, use this easy skin test throughout the day.

[h/t NPR]

Nearly Half of American Adults Don't Know Their Own Blood Type

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iStock.com/nzphotonz

If you know your blood type, you’re better off than nearly half of Americans. Of the 1004 adults in the U.S. who answered a recent Quest Diagnostics survey, only 57 percent said they knew whether they have type A, B, AB, or O blood.

This is roughly the same number of people who could recall their childhood phone number (55 percent), the survey revealed. By comparison, 74 percent of respondents remembered their lengthy Wi-Fi password, and 75 percent knew how much money was in their bank account.

For many, other personal health information was even murkier. Fewer than two in five people knew their cholesterol or blood sugar levels. Considering that these details provide important insights into one’s risk for certain diseases, survey administrators said this is a cause for concern.

“With consumers increasingly engaged in their own and their loved ones’ health care, it’s critical that they ‘know their numbers’—and have those numbers readily accessible—to ensure productive communication with their healthcare provider for both routine and critical care,” Cathy Doherty of Quest Diagnostics said in a press release.

With the exception of emergencies, at which time you may receive a universal donor's O-negative blood, doctors will almost always conduct blood typing and cross-matching tests to determine your blood type and identify minor antigens in your blood before conducting a transfusion or surgery.

It’s still important to know your blood type for other reasons. Newborn babies, for example, can develop hemolytic disease if their Rh blood type (meaning whether it's positive or negative) doesn’t match their mother's. And depending on your blood type, you may also have an increased risk for blood clots, heart disease, certain types of cancer, and even severe diarrhea and mosquito bites.

If you know your blood type, you’re also in a better position to donate blood and help people in need if there’s a natural disease or emergency, or if blood banks simply have a low supply. O blood tends to be the highest in demand (and O-positive is the most common blood type), but blood banks may issue public notices from time to time if they need a particular type.

If you’re unsure of your blood type, clinical labs like Quest Diagnostics offer blood type tests. You can also order test kits online from Amazon.

Can Watching the Super Bowl Give You a Heart Attack?

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iStock.com/skynesher

With the clock nearing zero, the 2006 divisional round playoff between the Indianapolis Colts and the Pittsburgh Steelers looked to be over: It was the fourth quarter, with one minute and 20 seconds left, and the score was 21-18. Pittsburgh held the lead and, by all appearances, was about to score again.

Pittsburgh's offense lined up on the Indianapolis 2-yard line and handed the ball to future Hall of Fame running back Jerome Bettis, a cannonball of a man who famously went by the nickname "The Bus." Nearly everybody assumed Bettis would pound the ball through the goal line. Instead, Colts linebacker Gary Brackett forced a fumble. The Colts picked up the ball and nearly ran it back for a touchdown. For Steelers fans, it was a sudden and heartbreaking turn of events. Literally.

Watching from a bar, a diehard Steelers fan named Terry O'Neill watched the ball tumble to the ground and suddenly felt a pain in his chest. Luckily, two firefighters in the crowd helped resuscitate him.

"My heart just quit beating completely," O'Neill later told the South Pittsburgh Reporter. "For all intents and purposes, I died."

Research indicates he wasn't the first. Watching a high-stakes game could actually kill you.

A 2002 study in The BMJ, which focused on the health of English soccer fans, found that a "myocardial infarction can be triggered by emotional upset, such as watching your football team lose an important match." A 2008 study published in the New England Journal of Medicine followed the World Cup-watching habits of German soccer fans and found that watching a stressful game more than doubled viewers' chances of experiencing a cardiovascular event. A similar result was found when other researchers looked at cardiovascular deaths in the Netherlands after the country's soccer team lost the European soccer championships on a penalty shootout in 1996.

In 2011, a study published in Clinical Cardiology looked at the Super Bowl specifically and found that deaths increased after the big game in the losing city, finding an "absolute increase in all cause mortality" in people over the age of 65. The researchers argued:

"Acute risk factors usually involve some form of stress—physical, emotional, or both—that increase the sympathetic nervous system and releases catecholamines. The subsequent increase in heart rate, blood pressure, and ventricular contractility increase oxygen demand and may change the shear stress of blood against an atherosclerotic plaque, contributing to plaque fracture."

This particular study, however, has received some criticism. It only looked at mortality statistics for the 1980 and the 1984 Super Bowls, a relatively small sample. Some researchers said the study went too far in implying that the Super Bowl caused death, considering that the viewer's behavior and health history (and not the events of the game itself) could have been responsible. Super Bowl Sunday, after all, is a day filled with fatty fried foods and copious amounts of alcohol—all possible risk factors for a cardiovascular event.

As Gregg Fonarow, director of the Cardiomyopathy Center at UCLA, tells LiveScience, "It may be other behaviors associated with important sporting events rather than the stress of watching the home team lose that may explain these associations." Additionally, pre-existing conditions could be a huge contributing factor. (This was the case for our fateful Steelers fan.)

Study limitations aside, becoming invested in the outcome of a sporting match is undeniably stressful on the heart. A recent (though small) study out of Canada surveyed the heart rates of hockey fans during games, revealing "a mean increase of 92 per cent among the 20 test subjects, rising from an average rate of 60 to 114 beats per minute," according to the Montreal Gazette. In other words, people sitting and watching TV had heart rates equivalent to people undergoing mild exercise. Their heart rates only got higher when they watched games in person.

Of course, you don't have to do a study to learn that close games can cause a diehard fan's heart to pound—just go and ask one. And if they mutter, "This team is going to kill me!," kindly suggest that they step away from the TV before it becomes a self-fulfilling prophecy.

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