The death in June of Maryland football player Jordan McNair has led to high school coaches placing a greater emphasis on hydration and heat-related issues. (Matt McClain/The Washington Post)

C.H. Flowers Coach Dameon Powell settled into the bleachers at Shepherd University’s football field on a humid July afternoon, having driven 90 minutes to support his defensive tackle, Jaden Thompson, at the college’s football camp.

Powell grew worried when the three-hour session ended. Thompson endured muscle cramps because of dehydration, causing him to limp around the facility until he tumbled to the ground.

A camp trainer provided Thompson liquids and set a cold towel over his body. Then Powell drove Thompson to a hospital, where the senior recovered after receiving intravenous therapy.

“I definitely learned my lesson,” Thompson said.

Many local high school coaches have been more attentive to instances like Thompson’s since Jordan McNair’s death in June. McNair, a redshirt freshman offensive tackle at the University of Maryland, collapsed because of heatstroke during a team workout May 29 and died in a hospital 15 days later. Maryland President Wallace D. Loh said the team didn’t provide McNair appropriate medical care.

Since area high school teams began practices in early August, coaches have taken extra precautions to ensure their players’ safety.

“With what [happened] at the University of Maryland, there’s a lot of people around the D.C. metro area that are on high alert,” Centreville Coach Chris Haddock said, “and that’s not necessarily a bad thing.”

During an afternoon practice in August, the Damascus coaching staff delivered critiques as the team prepared for a run at its fourth consecutive state championship. One player forgot his cleats, and another led with his head during blocking drills. But the loudest shouts came every 10 minutes, when the Swarmin’ Hornets stopped for water breaks.

“Water! Water!” each position coach shouted until every player took a sip from one of the many water bottles scattered across the field.

“Half the time they’re sick of getting water,” Damascus Coach Eric Wallich said, “because we’re forcing it down their throats so much.”

After North Point players lift at practice, the team holds a 20-minute period during which athletes hydrate before they take the field. When Tony Lisanti started coaching Chopticon 30 years ago, he said, he often held off granting water breaks. Now he walks around the field squirting water in players’ mouths.

Almost every school owns a tub that coaches fill with ice water before practices. If the school doesn’t have storage room for a tub, an athletic trainer folds a tarp and puts ice water in it, and a player can be placed inside. Every local school has at least one athletic trainer who can restrict teams from practicing outside or in pads based on the heat and humidity.

Local counties require coaches to complete heat acclimatization training at least every two years. Most counties set similar heat procedure guidelines, which advise if a player is overheating to remove his pads, place cold towels on his body, lay him in a cold tub and call emergency medical services if there are no signs of improvement.

“As a young teenager, sometimes we all think, ‘That’s not going to be me,’ ” Friendship Collegiate Coach Mike Hunter said. “When it hits closer to home, it kind of wakes them up.”

Bullis strength and conditioning coach Al Kallay posts a sign outside the school’s gym every afternoon that reads: “Leave your egos outside.” Part of the intended message is that Kallay doesn’t want athletes to feel they’re too tough to report heat exhaustion or lightheadedness because not doing so will hinder their performance and put their lives at risk.

That message has been crucial since McNair’s death, which was followed by reports that the Maryland football program looked down upon players who complained about injuries.

“The kid that comes out for football has to be tough,” Oxon Hill Coach Craig Jefferies said. “I don’t think you can coach toughness up. There’s ways to get the most out of your kids without taking their bodies to the point where there’s no return.”

Dizziness, the lack of sweating and headaches are some of the main heatstroke symptoms, but multiple athletic trainers said another important factor in identifying the condition is understanding their athletes’ tendencies and personalities. For example, they said, athletic trainers should pinpoint a problem when the most energetic player on the team has no intensity during a practice.

Athletic trainers study athletes’ medical and family health history to grasp issues that may cause athletes to become dehydrated or lightheaded. Many local teams use part-time athletic trainers, who attend practices and games. Full-time athletic trainers, who are hired by private schools and some counties, work at one school all day and have more time to familiarize themselves with athletes.

“Regionally, [McNair’s situation] really helped athletic trainers have to fight that battle [with coaches] a little bit less,” Spalding head athletic trainer Casey Berry said, “because it was in the back of everyone’s mind.”

Jennifer Rheeling, a D.C. Public Schools athletic trainer, said McNair’s experience might prompt local high schools to allocate more money toward safety resources. Even without those extra assets, though, McNair’s death has changed some athletes’ mentalities.

“When they see stuff at Maryland or they see our kids broke down,” Powell said, “they’re like, ‘It is real.’ ”