Click photo to enlarge
Doctor Joe L. Rod, 64, cardiologist, demonstrates, "Kriya", Ujjayi breathing technique , step one. Pranayama, consist of three stages, this is stage two Thumbs in armpit area, elbows parallel to grown and fingers directed towards the center at his home in Santa Clara, Calif., on Thursday, June 21, 2012. (Josie Lepe/Staff)

Breathing is one of the body's fundamental functions, yet most of us give it no more attention than we give the national product of Lichtenstein. We go about our day - doing routine tasks, making phone calls, handling problems, walking the dog - and unless we overexert ourselves or have an asthma attack, we don't have to think about breathing one little bit. It just happens.

"It is the first thing we do," says Dr. Margaret Chesney, a breathing researcher at UC San Francisco, "and it is the last thing we do. It's really important, but we take it for granted."

Yet we can control our breath if we choose. And breathing properly, experts say, can reduce stress and anxiety, improve mental focus and athletic performance, help control high blood pressure and mend other health problems.

Chesney and others point out that many of us have developed a habit of not breathing deeply enough, and unknowingly we hold our breath for short periods when under stress. Women are more prone to such "under-breathing," Chesney says. Both of these unconscious practices can raise carbon dioxide levels in our blood, which over the long term can be harmful.

"Short, shallow breathing causes a cascade of negative effects in the body, and the body associates that with the fight-or-flight response," says Al Lee, co-author (with Don Campbell) of the 2009 book "Perfect Breathing." "It gins up the adrenaline, the cortisol, the stress chemicals."

The good news, experts say, is that it's easy to retrain ourselves to breathe more effectively most of the time, the way we do when relaxed. And there's no equipment needed, no memberships -- we've got all the tools with us all the time.

The Lee and Campbell book draws from both recent research on respiration and the breathing techniques of traditional practices such as qigong and yoga. Lee notes that, although the idea of working on one's breathing "seems new age-y," his research has shown that athletes, elite military personnel, stage actors and singers all rely on breathing techniques to control and improve their levels of performance.

"These techniques are used by just about anybody in any discipline you can think of -- fighter pilots to Olympic athletes, marksmen, special forces, you name it," Lee says. "They would say, 'This is the most important thing I do.' "

Stress reduction was what Dr. Joe Rod, a cardiologist who's practiced for 30 years in San Jose, wanted a few years ago after going through a wrenching divorce. He signed up for a course in the multistage, rhythmic-breathing technique sudarshan kriya, but he was skeptical that it could really help him. Partly based on yogic breathing, or pranayama, it is taught by the international nonprofit organization Art of Living, whose founder is credited with developing the practice.

The effects were striking, Rod says. "After 90 days of doing this, I felt my stress was markedly reduced, and now I would not stop doing it, because I would not want to revert to the levels of stress I had at the time."

Rod practices his breathing for about 25 minutes daily and meditates as well. He has not missed a day in two years. His two adult daughters, impressed by the changes in their formerly 80-hour-a-week workaholic father, who was on the brink of starting antidepressant medications before improving his breathing, also chose to take the sudarshan kriya course, though he says that they don't practice it often.

Sudarshan kriya is sometimes criticized because part of the practice involves rapid, shallow breathing, which makes some people feel hyperventilated and dizzy. But that effect passes with practice, Rod says, adding that he has experienced no ill effects.

Rajshree Patel, a longtime teacher with the Art of Living and an ex-prosecutor in Los Angeles, recently led a series of free workshops on the breathing technique as part of the campaign Take a Breath, Bay Area. The benefits from the practice come over time, she says, and include better sleep, a stronger immune system and more energy.

"In a modern world of fast-paced, hectic life," she says, "it's the simplest, easiest and most natural way to go back to our center."

The primary function of breathing is to deliver oxygen to tissues, take carbon dioxide out of the body and regulate the acidity of our blood, says Chesney, who directs the Osher Center for Integrative Medicine at UC San Francisco. (Blood that is overly acidic prompts the kidneys to retain sodium, increasing blood pressure.) But there is plenty of evidence to show that breathing also is powerfully connected to our emotions and overall health, she says.

Currently, she and her husband, UC San Francisco adjunct professor of nephrology Dr. David Anderson, are studying the physiological means by which techniques such as yoga and meditation lower blood pressure. They are focusing on a group of women who are at risk of high blood pressure. The study quantifies the subjects' carbon dioxide levels under a variety of conditions. The hope is that, by teaching patients to practice deep, "mindful" breathing, they can lower high carbon dioxide levels and reduce high blood pressure.

Many breath-training techniques are being recommended and taught today, Chesney says, some of which emphasize a certain number of breaths per minute. But she prefers to focus on slow, relaxed, deep breathing -- the kind that makes our bellies rise and fall when we're not sucking in our stomachs.

"You can do that even in your car; you can switch off talk radio and put on some nice music," she says. A few weeks ago, when BART trains were halted for most of a day, many Bay Area residents felt stressed by the heavy highway traffic. Chesney points out that this kind of situation "is a chance to get either very angry and huff and puff, or maybe stop and breathe."

Castro Valley resident Jen Julian, 54, used to think about her breathing constantly, because it had become hard to do. Diagnosed several years ago with the lung disease chronic hypersensitivity pneumonitis, she found her condition worsening in 2005 and had to start using an oxygen tank constantly. She had noticed that just getting out of bed, taking a shower or doing laundry was exhausting. In 2006, under the care of the Stanford Center for Advanced Lung Disease, she underwent a double lung transplant and then had to relearn how to breathe normally.

The first deep breaths she took, about four days after surgery, were a pleasant surprise and a joy, she recalls. Now she is not only living life normally, but cycling, skiing and pursuing the lifelong dream of earning a pilot's license. She says she will never take breathing for granted again.

"I am kicking butt today, let me tell you," she says. "I take a deep breath every morning in honor of my donor."

Contact Sue McAllister at 408-920-5833. Follow her at Twitter.com/suemcal.