Researchers who analyzed the heat-related deaths of 58 football players nationwide found the numbers dramatically increased in recent years, and that most deaths have occurred during morning practices.
The University of Georgia researchers analyzed a detailed database of weather conditions such as temperature and humidity and the height, weight and position of the high school and college players who died.
The researchers found that about one player per year was dying in the mid-1990s. The study found that by 2009, the number had tripled to about three per year.
Six Georgia players died in that time, the most in the country.
Researcher Andrew Grundstein said he was surprised that more than half the deaths occurred during morning practices, when temperatures are generally cooler. But he said the research found that it's often very humid the morning, which increases heat stress on players.