Like snakes lurking in the tall grass, heat-related illnesses sneak up on their prey, basking innocently enough in the summer heat and humidity before striking. Worse, most who are bitten by the blistering temperatures refuse to believe they're suffering at all.

Hyperthermia, or heat-related illnesses, is best known for its most dangerous breeds: heat exhaustion and heat stroke, the latter of which requires immediate medical attention.

Heat-related maladies can progress in any order and at any rate, and the last person to recognize the effects is usually the athlete who is stricken.

Also dangerously misleading is the fact that information grows obsolete from one day or week or year to the next, and some information arises from questionable sources.

For example, the Red Cross now warns against taking salt tablets, which were handed out like a panacea against heat just a couple decades ago, because such a high concentration of salt may actually worsen the condition. Also, despite the widely televised relationship between the athletic exertion and the reward -- an ice-cold bottle of beer -- liquids with alcohol or caffeine in them can cause further dehydration, making conditions worse.

One reliable predictor of heat-related illness, however, is that children and the elderly are at particular risk, Healthline.com noted. In hot weather, a child's body temperature can rise three-to-five times faster than an adult's, reaching a dangerous level in a very short time, the National Weather Service Raleigh heat website ( www.erh.noaa.gov/er/rah/heat/) stated.

While there is a determined push to encourage kids to get off the couches, parents should still be cautious about sending kids outside for long periods during summer heat, University South Carolina researcher Russell Pate told USAToday.

"Make sure they have plenty of liquids so they stay hydrated, have them put on sunscreen, hats and sunglasses, and send them outside to play as much as possible," he said.

The elderly are also at greater risk, having less-efficient kidney function or underlying diseases that make them more vulnerable.

The obese and those taking medications to reduce excess body fluids (diuretics) can be at risk when conditions are hot and humid.

More and more recreation agencies and schools are looking to standardize policies which would govern when to proceed (or not) with rigorous scheduled activities in heat and humidity and providing clear cancellation policies.

Perhaps the closest thing to a universal standard governing workouts is offered by the National Federation of State High School Associations ( www.NFHS.org), which is a resource to which Carrboro Recreation Supervisor Charles Harrington often refers. A heat index for individual locations also can be determined by entering a zip code at the Oregon School Activities Association's website ( www.osaa.org/heatindex/)

This summer, Chapel Hill Parks and Recreation decided to stop playing summer basketball league games in Lincoln Gym, where, without air conditioning, conditions are known to become dangerously stifling for both participants and spectators.

"We still have it open for practices, but not for games," Chapel Hill Parks and Recreation Athletics Specialist Mike Troutman said. "Kids may have become accustomed to the heat, but parents and friends attending games might not be."

"The only two outdoor camps we have are ultimate Frisbee and flag football," Troutman added, "and both of those run only in the mornings, but we're also trying to come up with written policies: at what point do we need to call off practice and when is it safe to go ahead. Once football practice starts in August, that seems to be where we have the most questions."

Humidity can mitigate the body's ability to cool itself through perspiration. Tragically, we have been reminded of this fact several times over the past few years in central North Carolina.

Warning Signs

According to the American Red Cross, heat-related illnesses fall generally into the following three basic classifications:

Heat Cramps — if cramping is in multiple muscles, seek medical attention. Place victim at rest in a cool environment, provide a half glass of cool water every 15 minutes (with a teaspoon of salt per quart), or a commercial sports drink (e.g. Gatorade). Usually, rest and liquids bring about recovery, but victims should be carefully monitored for signs of worsening conditions. Lightly stretch the affected muscle and replenish fluids.

Heat Exhaustion — Victim is extremely sweaty, has cold or clammy skin, a mildly elevated temperature, pale color, dizziness, weak or rapid pulse, shallow breathing, nausea, headache, or unconsciousness. Move the victim immediately to a cool place out of the sun, preferably a cool, air-conditioned location. Hydrate and lay down with feet slightly elevated. Loosen clothing and supply cold (but not iced), slightly salty water or a commercial sports drink, provided in half-glass increments every 15 minutes. If symptoms persist, seek medical attention.

Heat Stroke — A life-threatening condition marked by a hot body with a core temperature as high as 104, red or flushed skin color, rapid or strong pulse, difficulty breathing, mental status changes. Emergency medical assistance should be called immediately. While waiting for help to arrive, take quick action to lower body temperature. Allow air to circulate around the body. Immerse in a cool bath or wrap the victim in wet towels or clothing and place ice packs in areas with the greatest blood supply. If the victim refuses water, is vomiting, or if there are changes in the level of consciousness, do not give them anything to eat or drink. After severe heat stroke, hospitalization may be necessary and bed rest is recommended for several days.

Heat-Related Illness Prevention

A few steps recreational athletes can take to Reduce Risk, according to the American Red Cross:

• Drink about 2.5 cups of fluid two hours before beginning activity and about two cups 10-15 minutes right before exertion; during exercise, drink up to one cup every 15 minutes. After exercise, drink until you have returned to your normal weight (16 oz. of fluid for every pound lost);

• Drink water or sports drinks with less than 10% sugar content. Do NOT drink caffeinated beverages like soda, iced tea, coffee, etc., and don’t take salt tablets, diuretics, or alcohol.

• Avoid strenuous exercise when it is very hot;

• Acclimatize: gradually increase workout intensity during summer months;

• Limit all exercise, inside or outside, during high heat index days;

• When possible, workout indoors or outdoors in shaded areas with good ventilation and off hot pavement or sidewalks;

• On hot days, exercise during early mornings when temperatures and humidity are lower;

• Wear light and loose-fitting clothing or technical wicking fabrics that allow the air to circulate around the body in hot weather and augment efficient perspiration;

• Eat lightly salted foods which can help replace salts lost through perspiration;

• Use sunblocks and sunscreens with a protection factor of SPF 15 or greater when exposed to direct sunlight;

• Pay special attention to activities and fluid intake among the very young and very old;

• Soak bandanas or other clothing in water to wear while working or playing in the heat.