When you breathe correctly—slowly, through your nose and into your diaphragm—your body has enough time over the course of each inhale to produce carbon dioxide. That CO2 buildup signals to the red blood cells that they need to send oxygen to the tissues and muscles. In turn, you get a little extra energy, explains James Breese, CSCS, a London-based educator who leads cardio programming workshops for Equinox trainers and coaches.
But for most people, everyday annoyances like traffic and loud noises put the body in a stressed state that causes them to take shorter breaths through the mouth, Berenc says.
That’s no good. You take in more oxygen in a shorter amount of time when breathing through your mouth, leaving no opportunity for the CO2 to accumulate, notes Breese. In turn, you don’t get all the energy you could from the air you inhale. In fact, Breese has seen people drop their 10K times by as many as five minutes just by switching over to nasal breathing during the day and while running.
When you’re training, over-breathing can make you tire out more quickly, Berenc says. The habit also slows recovery, in part because it affects your ability to sleep deeply. Thankfully, it’s a habit you can fix. Once you do, you’ll be able to exercise at harder intensities for longer periods of time and burn more fat for fuel, Berenc says, since the conversion process depends on oxygen uptake.
To find out, take the quiz below.
Your body can’t tolerate the CO2 buildup needed to release oxygen to the tissues.
Your ability to tolerate CO2 buildup is good, but worth improving.
You breathe correctly, which has given your body the ability to tolerate CO2 buildup.
Your body can’t tolerate the CO2 buildup needed to release oxygen to the tissues.
Your ability to tolerate CO2 buildup is good, but worth improving.
You breathe correctly, which has given your body the ability to tolerate CO2 buildup.
Your body can’t tolerate the CO2 buildup needed to release oxygen to the tissues.
Your ability to tolerate CO2 buildup is good, but worth improving.
You breathe correctly, which has given your body the ability to tolerate CO2 buildup.
Your body can’t tolerate the CO2 buildup needed to release oxygen to the tissues.
Your ability to tolerate CO2 buildup is good, but worth improving.
You breathe correctly, which has given your body the ability to tolerate CO2 buildup.
You’re breathing in too much oxygen, which prevents carbon dioxide buildup.
Good. You’re inhaling less oxygen, which allows carbon dioxide to build up so your tissues can actually utilize the oxygen you inhale.
You’re breathing in too much oxygen, which prevents carbon dioxide buildup.
Good. You’re inhaling less oxygen, which allows carbon dioxide to build up so your tissues can actually utilize the oxygen you inhale.
You breathe through your mouth while you sleep, which means you’re likely over-breathing.
Good. You breathe through your nose while you sleep.
You breathe through your mouth while you sleep, which means you’re likely over-breathing.
Good. You breathe through your nose while you sleep.
Snorers tend to breathe through the mouth overnight in an effort to get more oxygen into the body.
Good. You breathe through your nose while you sleep.
Snorers tend to breathe through the mouth overnight in an effort to get more oxygen into the body.
Good. You breathe through your nose while you sleep.
Your breathing is labored, which indicates it’s inefficient.
Good. Your body finds it easy to utilize the oxygen you inhale, so you’re not fighting for more with every breath.
Your breathing is labored, which indicates it’s inefficient.
Good. Your body finds it easy to utilize the oxygen you inhale, so you’re not fighting for more with every breath.
You’re constantly trying to inhale more oxygen.
Good. You use oxygen efficiently.
You’re constantly trying to inhale more oxygen.
Good. You use oxygen efficiently.
Stress may be causing your body to remain tense, which has affected your ability to tolerate carbon dioxide buildup.
Your body is at ease, allowing you to tolerate carbon dioxide build-up and better use oxygen.
That's it. The shorter you lasted during each test and the more "yes" answers you racked up, the more you over-breathe. Use the below strategies to correct the habit—and to reap the fitness and recovery benefits.
Focusing on your breathing mid-workout isn't enough. “The other twenty-three hours of the day have much more of an impact,” Berenc says.
The first step is to eliminate all (yes, all) mouth-breathing, especially when you’re walking around and climbing stairs. Berenc also suggests practicing the walking breath hold test as often as five times per day, every day.
If you need help reinforcing nasal breathing during your workouts, Breese recommends holding water in your mouth for a set period of time (even for up to 20 minutes) to force yourself to breathe through your nose.
There's only one time you should breathe through your mouth: in the middle of sprints or other HIIT intervals when you feel short of breath. “Just return to a calm, controlled nasal breath as soon as possible afterward,” Berenc says. Bonus: The switch lowers your heart rate more quickly so you're prepared for the next hard effort.
When recovering from intense bouts like sprints or heavy lifts, he recommends holding your breath for two to five seconds between each inhale and exhale to improve your efficiency and CO2 tolerance.
If you practice all these techniques, you should see improvements (around five extra steps during the walking test) within one or two weeks, Berenc says. To track your progress in the long term, do the BOLT once a week in the morning, before stress can affect your breathing. Your fitness and sleep will improve as a result.