Corrections & Clarifications: An earlier version of the articlecited an incorrect research journal for a study. The study appeared in the journal Dietetics.
If climate change has a color, it might be a deep shade of yellow.
Floris Wardenaar, assistant professor of nutrition at Arizona State University'sCollege of Health Solutions, creates this tint anda range of lighteryellow huesin his lab by mixing different amounts ofjuice, sodaor coffee inclear cups of water.
Then he puts them in front of college athletes and tells them to imagine it's their urine.
Withrisksof heat illnessrising in a warming climate, Wardenaarwants to know if studentsare able to accurately assess their own hydration status by observing the color of theirurine. As part of his research into theneeds of active populations living in a hot and dry environment,he creates and studies fake urine as an antidote, of sorts, toincreasing temperature averages and extremes.
Thirty-five student athletes at ASU signed up forWardenaar's test: 19female lacrosse players,11female triathletesand fivemale members of the football team. The results, published last month in the International Journal of Sports Science andCoaching, show that their eyes, on average, saw the fake urine as at least one shade lighter than it really was. This wasespecially true when the actual color was on the darker— more dehydrated— end of the spectrum.
These findings build on a body of research confirming that urine color is a reasonable indicator of its water content,regardless (mostly) ofany supplements taken. It also follows an earlier studyby Wardenaar,published in February in the journal Dietetics, that detected thesame tendency to score urine color lighter than it really is among 189 older athletes.
Together, theresultssuggestthatathletestend to haveoverly optimistic perceptions of their hydration status when estimating it based onthe color of their urine.
This type of work matters to people like Rebecca Stearns, COO of the Korey Stringer Institute at the University of Connecticut, which was established toaddress exertional heat illness afterthe sudden death of the Minnesota Vikingslineman during a practice session in 2001.
Stearns isan exercise physiologist and a seasoned runner. She alsofrequently works medical aid tents atmarathons and has had torevive many dehydrated and overheated athletes after theystumble across the finish line, blinded by their determination to how much they have put themselves at risk.
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Exertional heat stroke, Stearns said, is diagnosed by a body temperature of at least 104 degrees Fahrenheit and concussion-like confusion caused by central nervous system dysfunction.It can happen in a variety of climates and causes the untimely and preventable deaths of abouthalf a dozen high school and college athletes in the United States each year.
“We’ve shown that heat stroke can be 100% survivable," Stearns said. "Of the four main causes of sport-related deaths, heat stroke is also probably the cheapest one to treat. It only takes ice water, submersion therapy and a thermometer."
No one said being an athlete would be comfortable
Exertional heat stroke isn't just about dehydration andice baths. The importance of being hydratedincreases asathletes lose more fluid tosweat on hotter days. But in certainconditions, itwon't be enough.
One of the placeswhere Stearnssees the most cases every year is at the7-mile Falmouth Road Racein Cape Cod, Massachusetts, a destination known more as a summer beach escapethan for health-threatening hightemperatures. Another is the Marine Corps marathon, where combat-ready athletes may be especially likely to ignore warning signs andpush past their limits.
“Heat stroke can happen to the healthiest, most fit, perfectly prepared person," Stearns said. "I think that surprises a lot of people. You can be perfectly hydrated, in the best shape of your life and still get heat stroke. Environmental factors and the intensity of exercise above anything else is going to drive up yourbody temperature.”
Sweating is the body's way of trying to cool itself down, and the more hydrated you are, the moreyou can sweat.But that cooling effect only happens when the fluid evaporates directly off the athlete's skin, Stearns explained. Inhumid settings like Cape Cod, where the water vapor concentration in the air is already high, sweat may just drip from the body, offering little cooling benefit.
Surviving heat stroke depends on a combination of how much the body heats up and how long it stays at that temperature.
“You can survive a temperature of 110 if you cool off quickly, and you can die with a temperature of 106 if you’ve been at that temperature for a long time," Stearns said. "At about 105.5, you have cell death and your body can manage that for about 30 minutes. But at that point if you’re not cooled, your chances for survival go way down."
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To give overheated runners their best chance at a full recovery, Stearns and her team work quicklyat race medicaltentsto get the athlete into a tub of cold water, which can absorbexcess body heat,and to monitor their internal body temperature usingrectal thermometers.
Still, theheat stroke death toll has been on the rise in recent years.
A2020 heat death report from the Maricopa County Department of Public Heath concluded that the 323 local heat-associated deaths fromthat year representeda 62% increase over 2019and a 15-fold increase since 2001.The National Center for Catastrophic Sport Injury Research, based at the University of North Carolina atChapel Hill,reported 20fatalities among football playersat all levels in 2021. Three of those were recorded as exertional heat stroke deaths.
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Meanwhile,scientists have determinedthat the steadily rising concentration ofclimate-warming greenhouse gases in the atmosphere, largely from burning fossil fuels for energy, has already guaranteeda warmer future with additional weather extremes.
"The interesting thing with exertional heat stroke is we’ve been seeing concerning trends where it’s been increasing over the decades, Stearns said. "As opposed to some other injuries we’ve seen in sports like head injuries, where we’ve seen a big decline because of rule changes that have helped to reduce that. Heat illness is staying very relevant for many reasons."
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How to avoid rectal thermometers
At ASU, Wardenaar hopes to help athletes avoid all of the unpleasant realities of overexerting themselves in hot conditions. In addition to testing urine color perception, he has also studied the extent to which athletes are able to acclimatize to heat, or condition their bodies to be able to tolerate exertion athigher temperatures.
In a study published last year in theJournal of Strength and Conditioning Research, Wardenaar tested whether a five-day heat acclimation program could help athletes prepare their bodies forexerciseon hotter days. He had seven partially acclimated (Arizona-based) athletes bikefor an extra 60 minutesin a temperature-controlled room kept at 95 degrees on five consecutive days, while seven others didn't add anything to their training. Those whodid the extra biking registered slightly lower core temperatures and heart ratesin a later heat stresstest comparedwith thecontrol group.
The study was small and results were not statistically significant. But the "practical difference" wasenough for Wardenaar to practice what he preaches. As a former competitive cyclist, he prepares for Arizona summers by adding 45-minute outdoor biking sessions to his routine. On these excursions, he sometimes tests out different cooling vests, which hold cold water next to the skin, and heuses a "foothurt" test to gauge how much to push himself.
"Above 115 (degrees), especiallylater in the day,the tarmac on the road is just very, very hot," he said. "Even when biking, the ground can radiate so much heat that your feet hurt physically. That's personal experience, butI sort of have the feeling that when you feel that, there's nothing much beyond thatyou can push through."
Keeping your own limits in mind,emulatingsomething like Wardenaar's five-day heat acclimatization program, may beespecially beneficialin places like the desert Southwest, where dry air allowssweat to evaporate, aiding cooling. If you're not thetype to exert yourself for fun,just gettingoutside more can help prepare your body forheat.
"Many people in this area are car-bound, so they are not really exposed to the heat," Wardenaar said. "Extending the amount of time that you are out, even just gardening or reading the newspaperout on the porch, can help youto get better prepared for the actual summer heat. And if you keep doing this throughout summer, then normally you would be better able and capable of dealing with the heat."
Safety first
Regardless of an athlete'shydration or acclimatization status, withtriple-digit temperatures common in Arizona summers, there's still a physiological point at whichyour core body temperature will keep rising until you go into the shade or limit your exercise intensity, Wardenaar said.
In July 2021, the Phoenix Parks and Recreation Board voted to close popular hiking trailsto the public on days when the National Weather Service issuedan excessive heat warning. This usually happens when the heat index, a measurement of how hot the weather feels, exceeds105 degrees.The decisionaffected trails on Camelback MountainandPiestewa Peak, and was met with backlash fromrecreators who felt they could monitor their own safety.
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Death counts on these mountainssay otherwise. And, while some people might be able to manage it and make good decisions, the risksof granting unprepared hikersaccess in extreme heat extend to the rescue workers who have to go out in 115-degree conditions to retrieve individuals who overextendthemselves.
Without these interventions, and maybe with them, heat casualties are likely to climb alongsidethe warming influences of climate change. In 2021, the National Weather Servicerecorded 20 days forwhich there was a heat warning for Phoenix,11 in Yuma and 14 in the El Centro area.Numbers for 2022 are notupdated, but Phoenix's latest excessive heat warningis in effect, with trails closed Tuesday and Wednesday between 11 a.m. and 5 p.m.
For eachof the United States' 480,000college athletes and 8 million high school athletes, heat is an expandingobstacle toreaching theirgoalsin a warming world. Excessive heat also affects workers inphysically demanding or outdoor jobs.
“I don’t know what is going to happen with climate change," Wardenaar said. "We have huge distribution centers in this area that all need to be kept cool. If the actual temperature is rising in our environment and maybe also in a work environment, we need to adapt."
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Whether being able to accurately identify the exact hue of fakeurine could protectathletes and others from heat illness is unclear. (If you're worried, Wardenaar's latest paper suggeststhaturine color matchingcan improve with a mere five hoursof practice.)
What is clear (get it?), is that the risk of exertional heat illness is rising with average global temperatures, and thatnone of these deaths should have occurred.
Staying hydrated and monitoring nutrition while exercising, as well as making an effort to acclimate slowly to hotter conditions and paying attention to warning signs, can allowathletes to continue doing what they love and pushing througha hotter future.
The rest of us can help by supporting a societal shift away fromfossil fuels, switching to renewable energy sources and keeping in mind that allowing climate change to continue unabated will strike our vulnerable populations and young athletes first and most.
Joan Meiners is the climate news and storytelling reporter at The Arizona Republic and azcentral. Before becoming a journalist, she completed a doctoratein ecology. Follow Joanon Twitter at @beecycles or email her at joan.meiners@arizonarepublic.com.
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