Matthew Mayich stepped onto the field of Sun Angel Stadium in Tempe, Arizona, at about 7 a.m. on August 20. It was the standout hockey player’s first official practice with his new team, and temperatures were already in the mid-80s. He and his Arizona State University teammates spent at least 45 minutes doing push-ups, planks, flutter kicks, bear crawls, squats, sprints, and buddy-carries, led by guest trainer and former Green Beret Tim Ziesel. Before leaving the field, Ziesel gave instructions for one final exercise: a medicine ball run. As temperatures approached 90 degrees Fahrenheit, the players set off in small groups, according to the university’s timeline of events. Mayich appeared to struggle, then stumbled, dropped the ball, and fell. He tried to rise and fell again. Athletic staff treated him with iced towels and cool water, then sprayed him with a garden hose. Initially responsive, his condition deteriorated, and the trainer called 911. Paramedics rushed him to the hospital, where he remains in critical condition after experiencing what his family’s lawyer, Robert Carey, called exertional heat stroke. Carey did not respond to requests for additional information about the diagnosis, which could not be independently corroborated. He has told journalists the family’s hope for a meaningful recovery hovers near a miracle. ‘We want accountability for what happened to our son,’ Mayich’s parents, John and Christina, said in a written statement. ‘We want the truth.’ University officials declined to be interviewed, and Ziesel’s attorney, Larry Kazan, downplayed the intensity of the training session. ‘The workout was not difficult as some media outlets have attempted to color it,’ he wrote in an email to Grist. Head coach Greg Powers insisted during a September 23 press conference that he was still the ‘right guy’’ to lead the team but did not address specifics of the workout. ASU put him on paid leave Wednesday, more than a month after the workout and two days after seven of Mayich’s teammates impugned the school’s report and response in an anonymous letter sent via an attorney. Among other things, they said the workout lasted 75 minutes, not 45, and alleged that the university did not follow its own guidelines. ‘The precautions required by ASU’s heat policy were not in place: no immersion tub, no ice chests, no on-field heat measurement, no scheduled breaks in shade,’ they wrote, noting that the session ‘continued after some of us showed signs of distress, including dropping to a knee, vomiting and, in Matthew’s case, visible disorientation well before the final task.’ The St. Louis Blues hockey team selected Matthew Mayich during the 2023 NHL draft. He later transferred to Arizona State University to continue his college career. Jeff Vinnick/NHLI via Getty Images A St. Louis Blues prospect, Mayich, 21, had transferred to Arizona State to continue his college career. Instead, he is the latest in a long line of heat-related athletic tragedies that includes NFL player Korey Stringer, who died of heat stroke 25 years to the month before Mayich’s hospitalization. His death propelled heat safety into the national consciousness. ‘We have made tremendous progress since then,’ said Doug Casa, an exercise physiologist and certified athletic trainer. He is the CEO of the Korey Stringer Institute, which was established in 2010 to focus on safety and injury prevention for athletes, laborers, and warfighters. But he said Mayich illustrates that more can be done to protect players. Exertional heat stroke is a life-threatening condition that occurs when the body overheats and cannot cool down. It’s a leading cause of preventable sports deaths, and the risk is rising as climate change has made extreme heat more frequent, intense, and prolonged. Between 1994 and 2026 — the two times the United States hosted soccer’s World Cup — World Weather Attribution found that the chance of extreme temperatures ‘at least doubled’ in multiple cities. Grass fields have also increasingly given way to synthetic turf, which absorbs enormous amounts of heat. The surface temperatures at a recent Tennessee Titans football game in Nashville hit 157 degrees. One player rolled his ankle after the heat effectively melted his cleats, ESPN reported. ‘It was hot as s—,’ said another. ‘I didn’t play a snap, and I had to get an IV.’ Whether it’s an NFL star or a t-ball tot, athletes nationwide are facing this new reality. Some organizations have responded remarkably effectively — Georgia high schools instituted policies that moved them from the deadliest state for football players to among the safest. Others rely on vague recommendations and limited mandates that leave athletes at risk. And many policies don’t address non-athletes who are exposed to the same conditions. Just a week after Mayich’s hospitalization, University of Iowa band member Derek Phillips collapsed during a football game played in temperatures that topped 90 degrees. He later died. The policy landscape is full of holes, Casa said. Although best practices for preventing and treating heat-related illnesses in athletes are now largely established, consistent adoption and implementation is another matter. ‘A lot of times they know the right thing to do, but then they don’t do it in the time of crisis,’ he said. ‘Heat stroke can happen at any time.’ The Minnesota Vikings picked Korey Stringer in the first round of the 1995 draft and by 2000 he was selected to the Pro Bowl. The following summer he reported to training camp as one of the best offensive linemen in the NFL. By Minnesota standards, though, the temperatures were scorching and Stringer struggled. He vomited three times on the first day and left practice early to cool down in an air-conditioned trailer. The next day the heat index — a measure of temperature and humidity — hit nearly 100 degrees, but Stringer, despite vomiting again, completed the session. During a post-practice workout, he slipped, fell on his back, and was brought back to the air-conditioned trailer. He lost consciousness and was taken to the hospital, where doctors recorded an internal temperature of 108.8 degrees. He died of multiple organ failure thirteen hours later. He was 27 years old. The Minnesota Vikings football team drafted Korey Stringer in the first round of the 1995 NFL draft. Minnesota Star Tribune via Getty Images ‘It was a catastrophic failure in treating Korey,’ said Casa, who was an expert witness in the litigation that followed Stringer’s death, and in numerous other cases. ‘If they had treated him properly, he probably would have had dinner with his teammates that night, or at least been back to normal the next day. That’s how simple it is.’ Research by Casa and others has found that cold-water immersion is the most effective treatment for heat stroke, and is faster at cooling than air conditioning, which the Vikings relied on. Casa said that reducing Stringer’s temperature enough to save his life would have taken well over an hour with AC, compared to about 25 minutes in an ice bath. ‘The cooling rates are astronomical,’ said Casa. ‘We get their temps down so fast.’ The NFL would not provide a copy of its heat policy, but it did highlight the strengths of its protocol. Immersion tubs, for example, are required when hot weather is a possibility, as are rectal thermometers, which are necessary for diagnosing heat stroke. It also requires teams to adhere to best practices outlined by the Korey Stringer Institute, submit a plan for third-party review, and rehearse how they respond to emergencies. Exact interpretation is often left to each team or facility to allow flexibility, the league said, and clubs are encouraged to implement additional precautions whenever they feel there is a risk of heat issues. ‘I don’t think we have ever had a case where a team didn’t comply,’ said Allen Sillis, the league’s chief medical officer. ‘The NFL has really taken a leadership role since Korey Stringer’s death.’ Professional sports have largely standardized how they measure heat risk. Weather reports typically include temperature and heat index, which accounts for humidity. But the gold standard for measuring heat stress is wet bulb globe temperature, or WBGT, which also considers wind, sunlight, and radiant heat. ‘WBGT is a much better indicator,’ explained Jordan Clark, the co-founder and chief climatologist at Klimo Insights, a heat safety and weather app. Leagues still differ on their use of the metric. The NFL, for instance, requires teams to use WBGT but doesn’t specify exactly how. On the other hand, the National Women’s Soccer League mandates hydration breaks starting at a wet bulb globe temperature of 82.3 degrees and game delays when it tops 91.1 degrees. Teams that don’t comply can be disciplined or sanctioned. The NFL doesn’t enforce strict WBGT thresholds, so teams have the flexibility to invoke heat precautions more often. Not everyone’s attempt to address heat has been well received. FIFA required water breaks during this summer’s World Cup, even in air-conditioned stadiums, prompting accusations that it was creating commercial breaks rather than protecting players. ‘We had FIFA basically make a mockery of heat rules for commercial value,’ said Nicholas Watanabe, a professor of sport and entertainment management at the University of South Carolina. ‘Heat rules should exist specifically to protect people from heat.’ Policy differences aside, experts say professional leagues generally take heat seriously. The larger gaps emerge at lower levels. No federal regulations exist on heat safety in sports. Organizations like the National Federation of State High School Associations can and do provide guidance, for example, but states and even school districts can choose what to adopt. The Korey Stringer Institute has scored each state on its heat policies, awarding a maximum of 20 points for mandating things like requiring heat acclimatization, assessing wet bulb globe temperature, and making cold water immersion tubs available. Beating the heat High school heat safety policy score, U.S. states Points are awarded for mandates such as heat acclimatization, use of wet bulb globe temperature, and cold water immersion tub availability. Higher is better. Source: Korey Stringer Institute, University of Connecticut Clayton Aldern / Grist ‘There is a huge amount of disparity,’ in the results, said Christianne Eason, the organization’s president of sport safety and education. Thirteen states and Washington, D.C., scored 15 points or higher, while 17 came in at 5 points or below. Some of the strongest policies are in the Southeast, where heat and humidity can produce some of the nation’s most dangerous conditions. Georgia has led the way. Between 1994 and 2009, the state recorded six high school football deaths, which was among the highest in the country. After a string of high-profile incidents, officials examined what schools were doing in order to find ways to improve. ‘The policies for each school district were all over the map,’ said Bud Cooper, a clinical professor emeritus of kinesiology at the University of Georgia who was involved in that work. One school, he remembered, wouldn’t suspend practice until the heat index hit 140. But the research showed a clear trend, he said: ‘As the temperatures got greater and practices got longer, the risk went up.’ In 2012, the Georgia High School Association implemented some of the most robust policies in the country. Schools are required to take wet bulb globe temperature measurements and adjust practice lengths accordingly. Football teams also must abide by an acclimatization period that limits practices during the first five days of training so players can grow accustomed to the heat. Researchers found that, within three years, heat-related illness had dropped dramatically. The only heat-related death since the policies took effect, Cooper said, was Imani Bell, a 16-year-old basketball player who died after running stairs in extreme heat in 2019. Her family accused the school of violating the heat rules and settled with the district for $10 million; two coaches are awaiting trial on charges that include second-degree murder and involuntary manslaughter. Georgia’s turnaround shows that strict heat policies can work. ‘You could say it was luck, for one year, two years, three years,’ Cooper said, but it’s been about 15 seasons. ‘That goes beyond luck. That’s a result.’ The analysis by the Korey Stringer Institute shows that, aside from Vermont and New Hampshire, where officials have adopted stringent heat policies, many of the states that still have the most work to do are along the nation’s northern border. Even athletes in cooler climates need to acclimatize to summer temperatures, said Cooper, especially as climate change makes extremes and spikes more common. Pushing athletes into tough practices in hot conditions too quickly is a recipe for harm. ‘Those student athletes aren’t ready for that,’ he said. Some resistance to stronger heat policies centers on resources — school districts may worry about the cost of WBGT gauges, athletic trainers, or equipment like immersion tubs. But coaches also fear they won’t be competitive under new rules. ‘We had to reassure them that what they’re doing is the right thing,’ Cooper said of his experience in Georgia. ‘But at the end of the day, the level of play in high school football in the state of Georgia is still just as high as it was 15 years ago.’ High school athletic trainers in Norwich, Connecticut, douse a colleague in ice water during a training exercise meant to help them protect players from extreme heat. Cold water immersion is the most effective treatment for heat stroke. Mark Mirko/Connecticut Public via Getty Images Protections are even more important in youth sports, because children are more vulnerable to extreme heat. But deficiencies can be even greater, with policy development often falling to individual leagues, teams, or coaches, many of them volunteers. ‘It’s truly the wild west,’ said pediatrician and researcher Dr. Michele LaBotz, who wants heat taken as seriously as threats such as concussions or lightning. ‘There is not a mechanism yet for disseminating good information.’ College athletes are in many ways better positioned. Athletic trainers are more ubiquitous, and multimillion-dollar budgets make acquiring equipment less of an obstacle. But the NCAA has few heat-related mandates; most of its guidance is voluntary. ‘They have not been willing to make things required,’ said Casa. ‘You don’t get credit if it’s a recommendation.’ The NCAA confirmed that it provides ‘recommendations and guidelines’ but declined to answer follow-up questions on the record. The potential for confusion is evident in Arizona State’s heat policy, which runs three pages and uses the words ‘should,’ ‘will,’ ‘may,’ ‘can,’ ‘recommended,’ and ‘guidelines.’ On Friday, ASU announced that former Arizona Supreme Court Chief Justice Scott Bales will lead an independent review of the university’s planning, policies, and response to outdoor athletic activities, including the use of outside consultants. The university has asked Bales to complete the review by early December. In a statement that Carey released Friday afternoon, Mayich’s family welcomed Bales’ appointment but said the planned review does not go far enough. It wants an independent investigation of what happened on the field, who was responsible, and whether university, athletic conference, or NCAA rules were violated. Carey called on the university to expand Bales’ mandate to answer those questions or appoint a second independent investigator, and to make the findings public. Whatever comes of the review, ASU already had heat-safety measures that experts say could have protected Mayich – if they were followed. Mayich’s teammates described his collapse in detail, writing in their letter that ‘Matthew was unintelligible and non-responsive. His lips were gray.’ By the time paramedics arrived, he had been down for 17 minutes, during which ‘nothing effectively cooled him.’ They accuse the university of a slew of policy violations in the minutes, hours, and days leading to that moment. The missteps, they wrote, started at least eight days before the workout, when ASU hockey staff submitted an official request to have Ziesel lead it. The university timeline says the team did not include the required written activity plan, and it provides no indication that the request was reviewed or approved before Ziesel met with athletes, as school policy dictates. His lawyer, Kazan, told Grist in an email that ‘as far as he was told, he was approved by the coaching staff and they were aware of his leadership training plan.’ Mayich, who is from Ontario, Canada, arrived in Arizona eight days before the session. In theory, that was just enough time to complete the seven- to 14-day acclimatization period the university’s heat policy called for. But NCAA rules barred official practices until August 20. Voluntary workouts before then were held indoors with air conditioning and only short stints outdoors. That isn’t sufficient to induce acclimatization, Casa said. Research has shown that physiological adaptation takes repeated and gradually increasing exposure to heat. ‘Just being there,’ he said, ‘does nothing to help with heat acclimatization.’ When the opening practice finally arrived, the university policy ‘recommended’ that staff take wet bulb globe temperature readings. But the players wrote that ‘no WBGT instrument was on the field, and no measurement was taken at any point.’ The university’s report says it used data from a Weather Underground sensor roughly one mile away, with WBGT estimates, not measurements. University officials did not respond to written questions seeking clarification, but a 2021 study by researchers at the school found that taking readings at the stadium is a far more accurate indicator of potential heat stress. ‘On-field WBGT observations were, on average, significantly higher than WBGT estimated from regional weather stations,’ the authors wrote, noting a difference of more than four degrees. Practitioners, they said, ‘should not rely on regional weather station estimations without corrections.’ Mayich’s teammates said the practice occurred in full sun, suggesting the wet bulb globe temperature may have been at the higher end of the university’s estimates, which reached well into the 80s. But even the off-site measurements put at least part of the work out in the ‘high’ zone of the university’s heat-risk chart, under which only acclimatized athletes can participate. Matthew Mayich on the ice in Ottawa, Canada, in 2024. Chris Tanouye/Getty Images Whether Mayich was eligible to practice or not, his teammates wrote that he never got water. There was a brief opportunity to hydrate, but only those who finished the bear crawl first had time to do so. Mayich wasn’t one of them, the players wrote, and went without. He was also showing signs of distress well before the final exercise mentioned in the university’s report. ‘Matthew crawled on hands and knees and appeared disoriented. When he stood, he nearly fell,’ the teammates wrote in the letter. ‘In the buddy carry, one of us carried him, but he could not carry his partner back.’ Casa called all of that lead-up a ‘distraction’ from arguably the biggest issue: There was no immersion tub, which ASU’s policy called for in multiple places. After he fell, Mayich’s teammates said he spent ‘several minutes’ on the hot turf as people squirted him with water bottles and applied cold towels before he was moved to the shade. They briefly sprayed him with ‘warm water’ from a garden hose before police and paramedics took over, according to their letter. Mayich’s medical diagnosis may not be publicly revealed for some time. Based on what he’s read so far, Casa says that it’s ‘very likely a heat stroke’ but can’t say for certain without more information, such as rectal temperatures. In the meantime, Mayich has remained on life support at Barrow Neurological Institute. Just 2 miles away, ASU held an event on Tuesday to launch its new Center for Heat Preparedness. Scott Barclay, the university’s interim vice president of research, opened the day-long symposium extolling the importance of combating heat-related illnesses and death. ‘Heat is a killer,’ he said in his remarks, which didn’t mention Mayich. ‘In Phoenix, you don’t have to have that reminder.’ This story was originally published by Grist with the headline Extreme heat left this student athlete on life support. He won’t be the last. on Oct 5, 2026.