Heat-related illnesses that strike during a sport or recreational activity send nearly 6,000 people in the U.S. to emergency rooms every year, according to a report released today (July 28) by the Centers for Disease Control and Prevention.

These illnesses include heat exhaustion and dehydration, and males between the ages of 15 and 19 had the highest incidence, the report said.

All heat illnesses are preventable, the CDC said, and the findings highlight the need for effective heat illness prevention messages to target all physically active people, including those who participate in unstructured sports and recreational activities, and especially teens.

Heat illnesses have been recognized as a leading cause of death and disability among high school and college athletes, however, the rates of such illnesses among younger children and other adults was not known, the report said.

Males accounted for 72.5 percent of these ER visits, the study showed. The 15-19 age group accounted for the highest number of visits, with 35.6 percent. Those ages 10 to 14 accounted for 18.2 percent of visits, and those 20 to 24 for 10 percent.

Without prompt treatment, heat illnesses can lead to organ failure, brain damage and death, the CDC said. Most of the ER visits in the study did not lead to further hospitalizations — nearly 92 percent of people were treated and released.

The most common activities leading to these ER visits were football (24.7 percent), and exercise such as walking, jogging and calisthenics (20.4 percent). However, among those over 45, the most common activity that led to heat illness was golf.

Early symptoms of heat illness include dehydration, nausea, vomiting, headaches and dizziness, the CDC said.

Coaches of sports teams should schedule frequent breaks and encourage athletes to drink fluids, especially on hot, humid days, the CDC said. To allow athletes to get used to the heat, practices that begin during the summer should increase in their duration and intensity gradually. People participating in recreational activities should be aware of the risk for heat illness and potential prevention strategies.

The report was limited in that it included only non-fatal illnesses, and its conclusions are extrapolations from data gathered from 66 hospitals, the CDC said.

The report is based on data from 2001 to 2009 from the National Electronic Injury Surveillance System, which monitors injuries in hospital emergency departments. ER visits for heat illnesses that were related to work or military training were excluded.

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