Frigid conditions Friday and Friday night bring increased risk of hypothermia and frostbite for anyone not properly dressed for the outdoors.

"The people most at risk are little babies, children and the elderly," said Dr. Oliver Mayorga, chairman of emergency medicine at Lawrence + Memorial Hospital in New London.Extreme cold won't keep extreme athletes indoors

Hypothermia occurs when the body loses heat faster than it can generate it, resulting in abnormally low body temperatures that in severe cases can cause cardiac stress and even result in death. Anyone with a body temperature below 95 degrees can be considered to be suffering from hypothermia, but the usual cutoff for healthy adults is 89 degrees, Mayorga said. Frostbite, which is frozen body tissue, most frequently affects the fingers, toes, earlobes and nose, turning them very cold and pale.

"Frostbite can happen very quickly in these extreme temperatures that are coming," Dr. Nader Bahadory, chief of emergency services at The William W. Backus Hospital in Norwich, said Thursday. "If the frostbite is extreme, you can lose pieces of your fingers or nose."

Both doctors recommend that people dress in layers to allow space for cushions of warm air, and keep hands, face and head covered. They should also limit outdoor exposure, avoid alcohol — which lowers body temperature — and head indoors to warm up before symptoms such as shivering, disorientation and slurred speech occur. Simply going indoors to warm up cures mild cases of hypothermia and frostbite, but if symptoms are severe, people should see their doctor or seek care at the closest hospital, doctors said. Patients with severe hypothermia receive treatments of warm fluids and warming blankets, are put on heart monitors and may have to be hospitalized for two or more days.

People who find themselves becoming suddenly clumsy or awkward should heed this earliest warning sign and get out of the cold, said Dr. Hartmut Doerwaldt, physician at the Community Health Center in New London.

"And people should be prepared to bundle up in their cars with extra clothes and blankets, in case they get stuck," he said.

Temperatures are expected to hover around 18 degrees today, with wind chills of 7 below, then drop as low as 4 below zero by tonight, with wind chills of 13 below, according to the National Weather Service. By Saturday, the thermometer will climb back to the mid-20s.

When venturing outside today for shoveling, exercise, work or errands, the doctors advised, bundle up, take frequent warm-up breaks and change quickly if clothing gets wet with sweat or precipitation.

"And if there are elderly or young people you're taking care of, be prepared for them, too," Bahadory advised.

Pet owners should also limit time outdoors for dogs and cats, opting for shorter, more frequent walks and stints outside and more time indoors, said Dr. Sonya Swinamer, veterinarian at Companion Animal Hospital in Groton. She recommends a coat for small dogs and those with short hair that are most vulnerable to the cold, and rinsing paws after walks to remove irritating road salt.

"If it's too cold for us, it's too cold for them," she said. If a pet starts shivering or becomes unresponsive, it should be brought indoors to warm up slowly.

"Don't throw them in a hot bathtub," she said.

Those who live in neighborhoods with stray cats should consider opening car hoods before turning on the engine, Swinamer said.

"Cats will climb inside the cars and sit on the engine block to warm up, then get caught in the fan belt," she said, recalling several cats she's treated that were injured this way.

While many people need no encouragement to stay indoors as much as possible when Arctic temperatures descend, others consider the extreme cold something of an added challenge they're willing to take on to keep up their routines.

"You get bundled up and you go. You just keep riding," said Sean Ellis, manager at the Mystic Cycle Centre.

He plans to ride for about an hour today, using a bicycle equipped with studded tires and spikes for extra traction in the snow and ice. He'll be dressed with Neoprene covers over his shoes, AmFIB tights, three layers swaddling his arms and torso, "lobster mitts" on his hands, a hood over his head and face, and a ski helmet with goggles.

Physicians said outdoor exercise is safe in the extreme cold, as long as athletes are properly dressed and make sure they get out of wet clothing as soon as possible.

"Stay close to home, take extra care to protect yourself with extra layers, and if you work up a sweat, get inside," Doerwaldt said.

For keeping up his 8- to 16-mile-a-day running routine, Spyros Barres of Mystic fixes small screws into the bottom of his shoes for traction, dons windproof pants over tights, a windproof jacket over thermal and fleece layers, plus mittens and a hat.

"Once you get going, you stay warm," he said.

Another avid runner, Jim Roy of Mystic, said that after the first mile or so, he doesn't mind the cold.

"At first you wonder, 'Why am I doing this?' but at the end, you're always happy you did it," he said. "It's never too cold."

Heather Bessette, who owns the I Can Fitness personal training studio in Stonington, said she became steeled for running in single-digit temperatures while training for the Olympic marathon trials in 1996 during a particularly harsh winter. With a pair of Yaktrax on her running shoes and layers of clothing with "no skin exposed," she keeps up her 5- to 7-mile-per-day routine through the worst that winter can bring.

"I've been out in 5 below with no problem," Bessette said. "When you love it enough, you get out there no matter what."

j.benson@theday.com

Health tips for the extreme cold

■ Dress in layers.

■ Keep skin covered.

■ Avoid alcohol and caffeinated beverages, which make your body lose heat. Instead, drink hot, sweetened beverages to help stay warm.

■ Do outdoor work during the warmest part of the day.

■ Take frequent breaks from the cold in warm, dry shelters.

■ Know the signs of frostbite and hypothermia and seek medical treatment right away if symptoms occur.

■ Make sure infants stay warm. Infants under 1 year old should not sleep in cold bedrooms because they lose body heat more easily and are unable to shiver to keep themselves warm. Keep them properly clothed and indoors in warm temperatures.

■ Check on elderly neighbors and family members. People over the age of 65 often are less active and have lower metabolisms, making them lose body heat more quickly. Make sure that the temperature in their home is adequate.

■ Use portable generators safely. Exhaust from portable generators and outdoor grills contain carbon monoxide, which can be lethal. Do not bring outdoor grilling devices inside the home. Opening windows and doors and operating fans is not sufficient to prevent the buildup of CO in a home.

Source: Connecticut Department of Public Health