Killer heat

The calendar may say October but the thermometer still can scream August. Hike a steep trail on a hot fall day without proper hydration and nutrition, and it may be the last time you lace up your hiking boots.

Death by heatstroke is rare, but it happens. The death last month of a 22-year-old Ventura man while hiking on a day when temperatures reached the high 80s in the Rancho Sierra Vista area of the Santa Monica Mountains shows that heatstroke can strike regardless of age. The typical heat exhaustion victim at Grand Canyon National Park -- where the average high is 106 degrees in August in the inner canyon -- is a male in his 20s, officials say. Physical fitness doesn’t count for much when it’s hot.

Grand Canyon rangers call the medical conditions the “hazardous Hs” -- heat exhaustion, heatstroke and hyponatremia, an over-hydration illness in which the blood becomes depleted of important salts. There were more than 130 heat-related rescues last year at the park, but no heatstroke deaths. The last recorded heatstroke death at a national park was in June 2000.

It can be tricky to tell one “H” from another because the symptoms often are similar -- hyponatremia’s nausea and vomiting mimic heat exhaustion. And heatstroke victims don’t always show symptoms of heat exhaustion.

The key to spotting heatstroke is an absence of sweating. The body’s cooling mechanism malfunctions and, as a result, the core body temperature climbs to 105 degrees -- or higher. All the conditions involve fluid and nutrition imbalance. Don’t wait until you’re thirsty to drink water -- by then you’re already dehydrated.

Heat exhaustion is caused by dehydration due to intense sweating in hot weather. Hikers and runners can lose a quart or more of water in an hour, and if the water is not replaced, they may experience symptoms such as nausea, headaches, cramps, and cool and moist skin.

When the body loses its ability to regulate its temperature, something has gone haywire in the hypothalamus of the brain, which is the body’s thermostat. According to Dr. Wally Ghurabi, medical director of Santa Monica-UCLA Medical Center’s emergency care, the circuitry that carries involuntary messages that tell the body “sweat a little bit more, please” cease to function, a sure sign of life-threatening heatstroke.

On the trail, victims should be cooled with water and vigorous fanning; if there’s a creek, give them a soak. In fact, it’s a good idea to have extra water with which to douse yourself.

The obvious solution is to avoid strenuous hiking in direct sunlight when it’s hot. But if you must hit the trail, wear loose, lightweight, light-colored clothing (dark colors absorb heat while light ones reflect it), and drink water before and during the hike. Bring along at least several quarts.

Even if your water-filled Nalgene bottle is getting a workout, don’t forget to replace that other body essential -- electrolytes. If your hand hasn’t touched a salt shaker in years, leave behind the sodium phobia when you are on the trail. When you sweat, you lose important ions such as sodium, potassium and magnesium, which are needed to keep cells functioning.

Sports drinks can help replace electrolytes, but they “don’t even come close” to providing what a body needs, says Ivan Kassovic, a wilderness ranger at the Grand Canyon. “What we see a lot here is that people will drink Gatorade and eat PowerBars under the illusion they’ve replaced what they’re burning,” he says. “That’s a fantasy.”

“You need a good fire, and you’re feeding it with nothing but kindling,” says Kassovic of hikers’ reliance on sports drinks and energy bars. If dehydrated hikers are not used to consuming Gatorade and PowerBars, the food and drink will make them feel nauseated, he adds.

In addition, the average weekend warrior who gets in trouble on the trail can burn 3,000 calories but eats 500, he says. To stay healthy, Kassovic recommends eating salty foods as well as foods your body is used to. And, of course, keep drinking water. “Eat reasonable, realistic amounts of food,” he adds. “There’s nothing wrong with a peanut butter and jelly sandwich.”

To e-mail Julie Sheer or read her previous columns, go to www.latimes.com/juliesheer.