MISSION, Kan. -- Outdoor conditioning while a heat advisory was in effect during the humid summer left 15-year-old football player Ovet Gomez Regalado pale and asking for water. After a 15-minute exercise, he collapsed as he walked to a building at his suburban Kansas City high school and died two days later of heatstroke, the medical examiner's office wrote this month in a report that followed a weekslong investigation.

That makes Regalado the latest in a series of teen football players to succumb to heat-related illnesses during searing temperatures and high humidity. The Johnson County, Kansas, medical examiner’s report said the temperature on the fateful Aug. 14 afternoon was 92 F (33.

3 C). National Weather Service data shows temperatures rising over the the two-hour period that Regalado collapsed, from the mid-80s to around 90. The high humidity made it feel much hotter, though.

Obesity also contributed to his death; Regalado weighed 384 pounds (174.2 kilograms) and had sickle cell trait. People with the trait are more likely to have problems when their body needs extra oxygen, as happens in extreme heat and after intense exercise.

Jeremy Holaday, assistant executive director of the Kansas State High School Activities Association, said only weights and conditioning activities had been permitted since it was still preseason. “To our knowledge that is what was taking place,” Holaday said. He said the association recommends using a wet-bulb globe thermometer to monito.