An Arizona State University hockey player remains hospitalized five days after collapsing during an outdoor practice session, according to school officials. The incident, details of which have not been released by the university, occurred during a morning outdoor practice session Thursday, the first day of NCAA-approved activities for the men's hockey team.
The school has not released the student's name or condition, citing medical privacy. School officials did not immediately respond to ESPN's inquiries about the incident, which several reports attributed to high temperatures in the area that day.
Tempe Fire Medical Rescue was dispatched to Sun Angel Stadium, the school's track and field facility, at approximately 8:30 a.m. on Thursday for a "heat-related illness," according to The Athletic, which first reported the news.
Temperatures had reached 90 degrees with a relative humidity of 46% in the Phoenix area, according to data from the National Weather Service. The agency had issued an extreme heat warning for the region where temperatures in Tempe reached a high of 104 degrees, according to NWS records.
According to Dr. Hilary Fairbrother, a professor of emergency medicine at the McGovern Medical School at UT Health Houston, most people who suffer heat-related illness are typically in and out of an emergency room and do not require admission. She said heat-related illnesses can lead to a cascade of system failures and that damage can start "accruing quickly." She cautioned that in some cases, the heat can exacerbate other underlying conditions and might not be a specific heat-related illness.
Even early morning practices can be dangerous, said Brendon McDermott, director of the Heat and Hydration Optimization Lab at the University of Arkansas. He said that because humidity is usually higher earlier in the day, it can make cooling down more difficult.
"Some of the dangers in the morning are that we feel a little cooler because it is a little cooler outside, and when we feel cooler, we may work harder. And [humidity] limits sweat evaporation a bit more," said McDermott.
Normal temperatures in the pocket of air on an ice hockey rink are about 60 degrees -- a significant difference from what players would have experienced while training outdoors in Tempe.
McDermott said a 10- to 14-day heat acclimatization protocol would help athletes adjust to higher temperatures and reduce heat-related illnesses. Currently, the NCAA mandates a five-day heat acclimation protocol for football.
Chris Fiscus, vice president of communications for ASU, said in the statement that "the university offers its support for the student-athlete, their family and all of our student-athletes during this difficult time."
ESPN's Kyle Bonagura contributed to this report.