(CNN) -- Brutal summer temperatures will keep killing high school athletes unless their parents demand rules to protect them, says an expert in such deaths.
At least three heat-related deaths on practice fields have been reported in the past week, as high school football season nears. Two high-school football players from Georgia and a coach in Texas have died amid sweltering temperatures.
In addition, four high school players in Arkansas were hospitalized for dehydration as temperatures hit a record-high 114 degrees on Wednesday. The weekend death of a 28-year-old runner in a Kansas City, Missouri, endurance race also was blamed on heatstroke.
"We think it was the worst week in the last 35 years in terms of athlete deaths," said Dr. Douglas Casa, chief operating officer of the Korey Stringer Institute of health medicine at the University of Connecticut and author of the book "Preventing Sudden Death in Sports and Physical Activity."
Glenn Jones' son, Forrest, died days after a voluntary camp for his high school football team in Locust Grove, Georgia.
"I didn't think anything about it," Jones said. "He was giving signs. He wasn't complaining, but he was giving signs something was wrong."
Casa said until parents demand more specific and enforced rules for high school sports, these kinds of tragedies will continue.
The Korey Stringer Institute's namesake was a Minnesota Vikings player who died of heatstroke in 2001. His widow, Kelci Stringer, worked with Casa to create the institute to improve prevention.
There are no nationwide rules written to protect high school athletes from sudden death due to hot weather. But most state school athletic associations put out guidelines for districts to follow regarding dealing with extreme heat and other severe weather problems.
Jason West, communications director for the Missouri State High School Activities Association, said its member schools have to adopt some form of policy for dealing with hot weather. Missouri's state association advises coaches and marching band directors to take precautions when the heat index tops 95, and cut off activities when that measure hits 105, West said.
"If the heat index is over 105, then you stop, reschedule the practice for a later day or later in the day," he said. "If you can afford to do it at night, under lights, that would be even better, but we know some smaller districts can't."
Among the recommendations the association makes are frequent water breaks, and a trip to the scales at the beginning and end of each session. If a player's weight drops 3% or more, it's considered a sign of dehydration; losses of 5% are seen as an indicator of heat-related illness.
"That's going to be a strong signal," West said.
But Casa says there are no rules for coaches, and the guidelines issued by state athletic associations aren't binding.
"It's not like the NCAA, where they mandate rules and the colleges have to follow them," he said. "The high school association can make some recommendations, but they don't have any power or teeth to have those policies actually implemented."
Franklin Stephens, the head coach at Tucker High School in suburban Atlanta, said coaches have to watch out for players who try to keep going to make an impression, despite the heat.
"I think some of them do it, but as a coach you can see it," he said.
Casa said a task force made up of professionals from the top medical organizations in the country came together three years ago and produced a set of guidelines similar to those of the NCAA. The NCAA guidelines have been in place for eight years, and there's been only one heat-related death on a college football field since then.
One guideline is to have an athletic trainer on the field at all times -- a person trained in sports medicine who can not only recognize the signs of heat-related issues but also treat them. During August football practices in extreme heat, Casa said, most high schools have only the coaches on the field.
"So the coach is the one actually caring for these kids when they're in a life-or-death situation, which should scare the living daylights out of every parent in our country," he said.
Some high schools have put these guidelines into practice.
At St. Pious X Catholic High School in Atlanta, the athletic director monitors a device that measures heat, humidity and wind speed and calls off practice if conditions are too dangerous.
At Bishop Alemany High School in the San Fernando Valley of Los Angeles, where temperatures during August practices reach more than 100 degrees, head coach Dean Herrington says they do have a trainer on the field and more.
"We have a water trough on the side and our players know they can (use it) at any time during practice," he said.
Casa says it's not just about water.
"Heat strokes are completely survivable," he said. All that may be needed is an immersion in a cold-water tub or pool. An athlete who is immediately cooled can survive, but many schools and coaches just call 911, he said. Casa said while they wait for an ambulance the brain and vital organs continue to cook in the heat. The body can only withstand such extreme conditions for about 30 minutes.
CNN's Jim Roope and Matt Smith contributed to this report.