Why Breathing Through Your Nose Is Best

Breathing well begins with nasal breathing. For starters, the lungs don't like cold, dry air. Nasal breathing warms and humidifies your breath before it reaches the lungs. When you breathe through your nose, air travels past bony structures in the nasal cavity called turbinates, which are covered in soft tissue known as mucosa. These turbinates are what warm and humidify your breath.

Nasal breathing also cleans the air you breathe, thanks to tiny hairlike filters in the nasal cavity called cilia that act as filters. Cilia capture dust, pollution, allergens, smoke, bacteria, viruses and assorted other debris in the air you inhale and traps it in the mucous. From there, the debris is eventually pushed into your throat and swallowed.

Nose breathing also forces you to use your diaphragm, the muscle that sits below the lungs. Diaphragmatic breathing — or belly breathing (as opposed to chest breathing) — increases the efficiency of the lungs by activating the lower lobes, which contain a larger percentage of blood than the upper lobes.

But wait, there's more. Breathing through your nose also increases the amount of oxygen in your blood more than mouth breathing, which is essential to virtually every cell, organ and tissue in your body. That's because nasal breathing releases nitric oxide, an important molecule for blood vessel health. Nitric oxide is a vasodilator, meaning it relaxes and widens the blood vessels causing them to increase circulation. This allows blood, nutrients and oxygen to travel more efficiently throughout the body.

Nitric acid also decreases plaque growth and blood clotting. In fact, if the body doesn't produce enough nitric oxide, it can lead to heart disease, diabetes and erectile dysfunction.

Nasal breathing can improve athletic performance as well. Dr. John Douillard, trainer of elite athletes, conducted several studies in the 1990s comparing nose-breathing exercises to mouth-breathing exercises by hooking a group of cyclists up to sensors and recording their breathing and heart rates. He found that there was no significant difference in heart rate between the nose-breathing and mouth-breathing exercises.

But breath rates were consistently lower during nasal-breathing exercises. For example, one subject at maximum exertion on a stationary bike had a nasal breathing rate of 14 breaths per minute compared to a mouth breathing rate of 48 breaths per minute.

Perceived exertion was also significantly lower when nasal breathing, based on a self-reported scale of one to 10 with 10 being the most stressful. At maximum exertion on the stationary bike, participants rated their perceived exertion a 10 while mouth breathing but rated their perceived exertion a comfortable four while nose breathing.

Nasal breathing also activated the athletes' parasympathetic nervous system, which indicated that they were calmer and more relaxed when breathing through their noses compared to their mouths.

A 29-year study published in the journal Chest in 2000 showed that lung capacity has a lot to do with health and survival. People with smaller, less efficient lungs are more likely to get sick and die. Those with large lungs fared much better, Nestor writes in his book. And, he says, people can actually increase the capacity and size of their lungs, something he learned that while covering freediving for Outside magazine.

Freediving is a form of underwater diving that involves holding your breath for several minutes while diving down hundreds of feet into the sea. While training, athletes teach themselves to increase their lung capacity, some as much as 30 to 40 percent, Nestor writes in the book. They do this by practicing longer and deeper inhalation and exhalation stretches.

By exhaling very slowly, Nestor explains, the diaphragm "wakes up" and becomes more accustomed to a wider range so that it is easier to breathe deeply.

There are dozens of breathing techniques that can do everything from increase your body heat so that you can withstand extreme temperatures to those that can cause you to hallucinate. But if you're just getting started with breathing exercises, it's best to keep it simple, Nestor says. Even the simplistic breathing exercises "can be absolutely transformative," he says. "That's what the studies have shown."

Starting out, Nestor suggests a technique called "coherent breathing," which involves inhaling slowly for five to six seconds and then exhaling for the same amount of time. Studies have shown that coherent breathing can lower your heart rate and blood pressure while increasing the amount of oxygen to your brain. There are several YouTube videos that time the inhalations and exhalations so you don't have to keep an eye on your watch. (Coincidentally, several meditations, Ave Marias, and prayers adhere to the same respiratory rate, he says.)

For those of us who are prone to anxiety, Nestor recommends exhaling longer than you inhale. For example, inhaling for a count of three, then exhaling for a count of six or longer. "When you exhale you are eliciting your parasympathetic response," he says. "You're actually hacking into your nervous system and lowering your heart rate."