But the sight of Olsson and me with plugs and tape and whatever else in and around our noses has proven too much for locals to bear. Everywhere we go, we get either questioned or somebody’s long life story of breathing woes, how he is congested, how her allergies keep getting worse, how his head hurts and sleep suffers the worse his breathing seems to get.
I wave goodbye to Antonio, pull the visor of the baseball cap a little farther down to hide my plugged face and jog a few blocks to the gym. I make my way around women speedwalking on treadmills and old men on weight machines. I can’t help noticing that all of them are mouthbreathing.
Then I boot up the pulse oximeter, set the stop watch, hop on a stationary bike, latch my feet into the pedals, and I’m off.
The bike experiment is a repeat of several studies conducted 20 years earlier by Dr. John Douillard, a trainer to elite athletes, from tennis star Billie Jean King to triathletes to the New Jersey Nets. In the 1990s, Douillard became convinced that mouthbreathing was hurting his clients. To prove it, he gathered a group of professional cyclists, rigged them up with sensors to record their heart rate and breathing rate, and put them on stationary bikes. Over several minutes, Douillard increased the resistance on the pedals, requiring the athletes to exert progressively more energy as the experiment went on.
During the first trial, Douillard told the athletes to breathe entirely through their mouths. As the intensity increased, so did the rate of breathing, which was expected. By the time athletes reached the hardest stage of the test, pedaling out 200 watts of power, they were panting and struggling to catch a breath.
Then Douillard repeated the test while the athletes breathed through their noses. As the intensity of exercise increased during this phase, the rate of breathing decreased. At the final, 200-watt stage, one subject who had been mouthbreathing at a rate of 47 breaths per minute was nasal breathing at a rate of 14 breaths a minute. He maintained the same heart rate at which he’d started the test, even though the intensity of the exercise had increased tenfold.
Simply training yourself to breathe through your nose, Douillard reported, could cut total exertion in half and offer huge gains in endurance. The athletes felt invigorated while nasal breathing rather than exhausted. They all swore off breathing through their mouths ever again.
For the next 30 minutes on the stationary bike, I’ll follow Douillard’s test protocol, but instead of measuring exertion with weight, I’ll use distance. I’ll keep my heart rate locked in to a consistent 136 beats per minute while measuring how far I can go with my nose plugged and breathing only from my mouth. Olsson and I will come back here over the next several days, then return next week to repeat the test while breathing only through our noses. This data will provide a general overview of how these two breathing channels affect endurance and energy efficiency.
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To understand how breathing affects athletic performance, we first need to understand how the body makes energy from air and food. There are two options: with oxygen, a process known as aerobic respiration, and without it, which is called anaerobic respiration.
Anaerobic energy is generated only with glucose (a simple sugar), and it’s quicker and easier for our bodies to access. It’s a kind of backup system and turbo boost when the body doesn’t have enough oxygen. But anaerobic energy is inefficient and can be toxic, creating an excess of lactic acid. The nausea, muscle weakness, and sweating you experience after you’ve pushed it too hard at the gym is the feeling of anaerobic overload. This process explains why the first few minutes of an intense workout are often so miserable. Our lungs and respiratory system haven’t caught up to supply the oxygen our bodies need, and so the body has to use anaerobic respiration. This also explains why, after we’re warmed up, exercise feels easier. The body has switched from anaerobic to aerobic respiration.
These two energies are made in different muscle fibers throughout the body. Because anaerobic respiration is intended as a backup system, our bodies are built with fewer anaerobic muscle fibers. If we rely on these less-developed muscles too often, they eventually break down. More injuries occur during the post–New Year’s rush to gyms than at any other time of the year, because too many people attempt to exercise far over their thresholds. Essentially, anaerobic energy is like a muscle car—it’s fast and responsive for quick trips, but polluting and impractical for long hauls.
This is why aerobic respiration is so important. Remember those cells that evolved to eat oxygen 2.5 billion years ago and kicked off an explosion of life? We’ve got some 37 trillion of them in our bodies. When we run our cells aerobically with oxygen, we gain some 16 times more energy efficiency over anaerobic. The key for exercise, and for the rest of life, is to stay in that energy-efficient, clean-burning, oxygen-eating aerobic zone for the vast majority of time during exercise and at all times during rest.
Back in the gym, I pedal a little harder, breathe a little deeper, and watch as my heart rate increases steadily, from 112 to 114 and on up. Over the next three minutes of warm-up, I need to get to 136 then keep it there for a half hour. This rate should be right at the aerobic/anaerobic threshold for a man my age.
In the 1970s, Phil Maffetone, a top fitness coach who worked with Olympians, ultramarathoners, and triathletes, discovered that most standardized workouts could be more injurious than beneficial to athletes. The reason is that everybody is different, and everybody will react to training. Busting out a hundred pushups may be great for one person but harmful to another. Maffetone personalized his training to focus on the more subjective metric of heart rates, which ensured that his athletes stayed inside a defined aerobic zone, and that they burned more fat, recovered faster, and came back the next day—and the next year—to do it again.
Finding the best heart rate for exercise is easy: subtract your age from 180. The result is the maximum your body can withstand to stay in the aerobic state. Long bouts of training and exercise can happen below this rate but never above it, otherwise the body will risk going too deep into the anaerobic zone for too long. Instead of feeling invigorated and strong after a workout, you’d feel tired, shaky, and nauseated.
Which is basically what happens to me. After I do a half hour of vigorous pedaling and openmouthed huffing, the clock on the stationary bike ticks down to zero and the whirling gears slow to a stop. I’m sweating profusely and feel bleary-eyed, but I’ve pedaled a total of only 6.44 miles. I scoot off the bike and let Olsson take a spin, then it’s back to the home lab for a shower, a glass of water, and more testing.
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Decades before Olsson and I jammed our noses shut, and before Douillard put his cyclists through the rounds, scientists were running their own tests on the pros and cons of mouthbreathing.
There was Austen Young, an enterprising doctor in England who, in the 1960s, treated a slew of chronic nose-bleeders by sewing their nostrils shut. One of Young’s followers, Valerie J. Lund, revived the procedure in the 1990s and stitched the nostrils of dozens of patients. I repeatedly tried to contact Lund to ask how her mouthbreathing patients fared after weeks, months, and years, but never got a reply. Luckily, those consequences were spelled out by a Norwegian-American orthodontist and researcher chasing very different ends.