Your Body on the Polar Bear Plunge

If Nora Gross had known what she knows now on New Year's Day 2006, she might be short a good story -- and $75. Gross, who was 22 at the time, jumped in freezing water off Coney Island because a bartender had bet her $75 she wouldn't do it. She did.

"It's totally exhilarating," remembers Gross, who plunged with a friend after a night of partying. In her company? "All kinds of characters," ranging from older adults who swim in cold water regularly to partyers in matching wigs to bodybuilders in bow ties. "It's a scene," she says.

But Gross, now a 32-year-old massage therapist in New York City, won't be in that scene again. She was more "party hardy" back then, she says, and lacked the health knowledge that came with her professional training. "I don't think that's going to be the thrill that I seek again -- now knowing what I do about the body," she says.

Each New Year's Day, hundreds of people join the Coney Island Polar Bear Club for the annual swim. Similar events -- which usually involve jumping or running into a natural body of (typically icy) water for a few minutes, oftentimes for charity -- draw thousands around the country. About 10,000 people, for example, jump into the Chesapeake Bay each year during Maryland's Polar Bear Plunge to raise money for Special Olympics Maryland, according to Greg Shipley, a spokesman for the Maryland State Police, which sponsors the plunge. "The event has grown where we have to break it into multiple days and plunges," he says.

While such events are entertaining and can be quite charitable -- the Maryland State Police's plunge aims to raise $2 million each year, Shipley says -- it's not without risks.

"If you want to swim in the cold water, and that helps you feel invigorated, I think that's wonderful," says Dr. Joshua Tobin, director of trauma anesthesiology at the University of Southern California Keck School of Medicine. "But that should be part of your regular exercise routine -- that shouldn't be something you throw together with your drinking buddies at 3 in the morning on New Year's Eve."

Cardiac Confusion

When Emily Johnson did her first (and last) New Year's Day plunge at a camp in her early 20s, it nearly took her breath away. "You can almost not help yourself from gasping," says Johnson, now a 28-year-old clinical exercise physiologist at Washington State University.

Now, she knows what that's called: The cold shock response, or the body's fight-or-flight reflex that causes blood vessels in the skin to constrict in order to send blood to organs such as the heart and the brain. It quickens your breathing and speeds up your heart rate. You'll probably find yourself shivering, too -- your body's attempt at making and conserving heat. "That first response ... makes your body ready to increase body temperature and metabolism and get ready for shock," Johnson explains.

Gasping for air is part of that reaction. "If you're jumping into cold water and you gasp and it's timed wrong, you can actually get cold water in your lungs and that's very dangerous," she says. In other words: You can drown.

Next comes the "diving reflex" that happens to all mammals when their faces submerge in cold water, Johnson says. Like the cold shock response, this reflex sends blood away from the skin and toward the inner organs. But unlike the earlier response, it tells the body to breathe more slowly and slow down its heart rate. "This is basically designed to save oxygen and send it to the heart and the brain," Johnson says.

While the responses are designed to keep you alive, experienced together, they can spell trouble. "Having those opposing effects on the heart -- where it's telling your body at once to both increase heart rate and decrease heart rate -- can be very dangerous because it can actually cause an arrhythmia," or an irregular heartbeat, Johnson says.

In the worst-case scenario, that can kill you, says Dr. David Farcy, an emergency medicine physician who serves on the American Academy of Emergency Medicine's board of directors. What's more, the longer you stay in the water, and the more your body temperature and heart rate drop, the more likely to you are to experience a condition called tetany. "The heart freezes and stops," Farcy explains, "and that causes death." While rare, there are indeed reports of people dying after participating in a polar bear plunge.

Taking the plunge? Read on.

All risks considered, most people who brave a polar plunge live to tell the tale -- and, in Gross' case, to collect their winnings.

"In a normal, healthy, nonintoxicated individual, jumping in cold water resulting in what we call mild hypothermia ... is extremely well-tolerated," Farcy says. "It gives them a rush of adrenaline, they feel great and, medically, cold has been used for centuries as a method to treat injuries." Even Farcy has dunked into ice cold water in hopes of healing a sports injury before a race. (It didn't work.)

But there are some people who definitely should not take the plunge. Namely, people with high blood pressure or conditions like heart disease. "In someone who has a heart condition, you're suddenly increasing heart workload and that can ... put you at risk for a heart attack," Johnson says.

People who are intoxicated should also say no to polar plunges -- or any plunges for that matter, says Tobin, a member of the American Red Cross Scientific Advisory Council. "If you've been drinking and get in the water, it can be 80 degrees in Hawaii, and your risk of drowning is significantly increased," he says. "So if you've had a few drinks, I'd strongly advise not dipping one toe in the water."

Alcohol also interferes with your body's natural responses to cold water, since it dilates your skin's blood vessels while your other reflexes want them to constrict. (That's the case even if your last cocktail was hours ago, though to a lesser extent.) In effect, you feel warmer, but your internal organs get colder faster, Johnson says. There's also the mental effects of alcohol that can interfere with your decision-making, she adds. "[Alcohol] changes your perception of the cold, and you might stay in the water for longer because you feel warm and you don't realize how cold your internal core temperature is."

In addition to people with heart conditions and alcohol in their systems, people who smoke -- even if it was just for the night -- should take extra caution because nicotine constricts blood vessels and further confuses the heart in a cold water situation, experts say. Smokers are also more likely to have respiratory problems that cause them to hyperventilate while submerged -- a reaction that lowers the amount of carbon dioxide in the blood and can lead to confusion, muscle cramping, fatigue and more, Farcy says. If you're on any prescription medication, talk to your doctor first, he adds.

People who are very thin, older adults with little body fat and children also tend to fare worse in polar plunges since their body temperatures drop more quickly, Johnson says. (The Maryland State Police Polar Bear Plunge, for example, requires a parent's signature for under 18-year-olds to participate.) Tobin adds to the high-risk list people who are very out of shape or who aren't good swimmers. "I wouldn't advise someone who hadn't exercised all year on New Year's to go sprint up a snowy hill on a cold day in their shorts," he says. "I think that would be a similarly bad idea."

Still determined to start the new year off with an ice cold splash? Here's how to plunge as safely as possible:

1. Prepare.

Gross admits she and her friend hardly prepared. They stayed out all night the night before, bought clothes to jump in from a drugstore and changed out of their sequin dresses in a cold public bathroom on Coney Island. After the plunge, they put their dresses back on and rode a train all the way back to New York City. Needless to say, "the ride home was not a lot of fun," she says.

For a more comfortable (and less risky) experience, make sure you have plenty of warm, dry clothes, a towel and shoes ready for your resurgence -- not a shot of whiskey, Tobin advises. "Dry equals warm," he says. Johnson also suggests making sure you have a heated car ride home. "Park it nearby, and leave it running with someone in the car."

If you've been planning your plunge for months rather than days or hours, practice swimming in cooler water or even taking frequent cold showers. Some research suggests that can help lessen your shock response, Johnson says.

2. Grab a buddy (or two).

Most people want to kick off the new year surrounded by family and friends -- and that instinct is even more critical in the case of a polar plunge, Tobin says. "Even fit, healthy Navy divers don't do anything without their swim buddy," he says. Take their lead and jump in with a friend -- and make sure he or she gets out when you do.

It's also important to have friends -- sober friends -- on the shore who can perform CPR if need be, Johnson adds. It's even better if the host organization has emergency personnel on hand. "You just don't know what's going to happen, and it's dangerous on the heart," she says.

3. Make it quick.

If you're healthy and sober, jumping in the cold water for just a minute or so is unlikely to have any ill effects, since the immersion won't be long enough to affect your core body temperature, Farcy says. To prevent the involuntary gasp and potential water inhalation, hold your breath when you jump in, Johnson suggests. You can also reduce the workload on the heart by going in slowly and keeping your head above water. "It's the submersion and having cold water on your face that activates your diving reflex," Johnson says. For people with heart conditions especially, "that's when things get real dangerous because your heart is getting two opposing signals at the same time."

4. Know the signs of hypothermia.

While the biggest risk of polar plunges is to the heart, hypothermia is also possible -- particularly if you hang around in the water or don't warm up appropriately afterward. That's why it's important to know the signs -- shivering, sudden severe fatigue, goosebumps and loss of coordination -- in you and your friends, Johnson says. (You can also download and use the American Red Cross' first aid app, which can help you diagnose hypothermia and frostbite.) If symptoms don't go away after changing into dry clothes and moving to a warm place, it's time to get to an emergency department. "I think sometimes," Johnson says, "people don't realize this advice is serious."