Most people don’t know how to breathe properly. And while that may sound hyperbolic, by the end of this article, you’ll be questioning how you’ve been breathing throughout your life—especially in high-stress situations.
The average person takes approximately 25,000 breaths a day. It’s more than just something we do to stay alive—it affects more aspects of our lives than most people realize. Things like shaping the structure of our face, snoring, asthma, allergies, sleep apnea, stress levels, blood pressure, and, in reference to this article, performance.
I’ve used box breathing before, and it works—but it has some downsides. The counting can feel like a mental chore, especially when you’re already dealing with chaos (or on your way there). I’d rather use breathing techniques that are easier to execute under pressure and still give you the same—or better—control.
Breathing Is More Than Just Air Movement
One of the core misunderstandings about breathing is the belief that its primary purpose is to bring more oxygen into the body. In reality, the human body already carries a surplus of oxygen. At rest, we exhale up to 75% of the oxygen we inhale, and even during intense exercise, we still exhale roughly 25%. The problem is rarely oxygen availability—it is oxygen delivery to the cells.
Carbon dioxide (CO₂), commonly mislabeled as a waste gas, plays a critical regulatory role. CO₂ is required for oxygen to be released from hemoglobin and delivered to tissues such as muscle, brain, and cardiac tissue, to name a few. When breathing becomes excessive—too fast, too deep, or primarily through the mouth—CO₂ levels drop too low, impairing oxygen delivery at the cellular level in these tissues.
Overbreathing alters blood chemistry by lowering CO₂ and reducing bicarbonate buffering capacity. This leads to vasoconstriction, reduced circulation, and a stronger bond between oxygen and hemoglobin, meaning oxygen stays trapped in the blood instead of reaching muscles, the brain, and vital organs.
In short: breathing harder does not equal better oxygenation. In fact, it hinders performance.
Nasal Breathing and the Diaphragm: Mechanical Advantages
One way we can ensure that we aren’t overbreathing is nasal breathing. Nasal breathing fundamentally changes how air moves through the respiratory system. “Deep” breathing does not mean taking more air in—it means breathing lower, farther from the top of the lungs. The lungs are triangular, and the greatest concentration of blood flow occurs in the lower lobes.
Mouth breathing disproportionately ventilates the upper portions of the lungs, where blood flow is lower. Nasal breathing encourages diaphragmatic activation, drawing air deeper into the lungs where gas exchange is most efficient.
Nasal breathing also introduces mild resistance. This resistance forces greater diaphragmatic engagement and reduces reliance on accessory muscles of the chest and neck. Over time, the diaphragm adapts and strengthens, just like any skeletal muscle.
As Dr. George Dallam—who has extensive research on nasal breathing—analogizes, this is similar to training a cyclist to pedal a larger gear: initial fatigue gives way to greater efficiency and capacity.
Furthermore, the nose functions like a muscle—if you don’t use it, you lose it. This has been shown in people with laryngectomies. After just two years of breathing through a stoma (neck opening), their nasal passages can become completely plugged.
Carbon Dioxide: The Gatekeeper of Oxygen Delivery
Carbon dioxide is not merely tolerated by the body—it is required. CO₂ acts as a vasodilator and bronchodilator, opening blood vessels and airways. As you learned above, it also governs the release of oxygen from hemoglobin through the Bohr effect.
When CO₂ levels fall:
- Blood vessels constrict
- Bronchioles tighten
- Oxygen remains bound to red blood cells
- Tissue oxygenation decreases
This explains why people can feel air-hungry, lightheaded, or fatigued despite normal blood oxygen saturation.
Pulse oximeters (the finger sensor) only show how much oxygen is in your arterial blood—not whether that oxygen is actually getting into your tissues and being used.
Experiments show that simply reducing breathing rate from 18 breaths per minute to 6 can increase CO₂ levels by up to 25% while maintaining full oxygen saturation. Less breathing—not more—is often the solution.
Overbreathing, Stress, and Nervous System Activation
Breathing and stress have a bidirectional relationship. Stress changes breathing—but breathing also creates stress.
Overbreathing—especially through the mouth—activates the sympathetic nervous system. A dry mouth is one of the earliest indicators of sympathetic activation. Conversely, slow, quiet nasal breathing increases saliva production and shifts the nervous system toward parasympathetic dominance.
When breathing is fast and heavy:
- CO₂ drops rapidly
- Cerebral blood flow can decrease by up to 40%
- Anxiety, panic, and brain fog increase
Just 30 seconds of hard breathing can cut CO₂ levels in half. The resulting vasoconstriction—not lack of oxygen—is what produces lightheadedness and tingling sensations.
Breathing Efficiency and Cognitive Control Under Stress
The brain can regulate its own excitability through breathing. Scientists at Stanford Medical School identified a respiratory pacemaker in the brainstem that directly influences emotional state.
Fast breathing agitates neural activity. Slow breathing calms it.
This has direct relevance for law enforcement, where decision-making, situational awareness, and emotional control under stress are critical. Telling someone to “calm down” rarely works. Activating the parasympathetic nervous system through breathing does.
A Breathing Technique for Rapid Stress Reduction
When overwhelmed and stressed—and you want to adjust your mind and be clear—you have to take an approach that involves actions of the body.
It’s very hard to beat the mind and calm ourselves down using the mind. Breathing is a way to use the body to calm the mind. This is because the diaphragm is a skeletal muscle that we have control over, unlike many other organs. The diaphragm is connected to the brain by something called the phrenic nerve.
It was recently discovered that there are about 200 neurons (nerve cells) that live in the brainstem. They control a specific pattern of breathing that was designed over hundreds of thousands of years to calm animals and human beings quickly.
While we don’t want to overbreathe and get rid of too much CO₂ chronically, there are times when we can use specific breathing methods to reduce stress and anxiety. One of those is called the physiological sigh.
It activates the phrenic nerve in a particular way. The pattern of breathing is a double inhale followed by an extended exhale. Dogs do this right before they take a nap. When you inhale normally you inflate these little sacs in the lungs. That second little inhale at the end brings them to a more rigid form that helps clear excess carbon dioxide from the bloodstream—so when you exhale, you offload extra carbon dioxide.
There’s another set of neurons in the brainstem that measure carbon dioxide in the bloodstream, and they are largely responsible for setting your levels of stress and anxiety. Just two or three of these physiological sighs can bring down stress faster than almost anything else.
Because it bypasses conscious thought, it works when cognitive control is compromised—exactly the conditions officers experience in real-world encounters.
Breath Holds, CO₂ Tolerance, and Diaphragm Strength
Breath-hold time is primarily determined by:
- Metabolic rate
- CO₂ tolerance
- Total body gas storage
The primary stimulus to breathe is carbon dioxide, not oxygen. Oxygen only triggers breathing when levels drop dangerously low (~50%). Most people have poor CO₂ tolerance, not low oxygen.
Holding the breath after exhalation strengthens the diaphragm by forcing respiratory muscles to contract with conscious control while airflow is paused. This also creates intermittent hypoxic stress, which can simulate altitude exposure within days of practice.
Holding after inhalation, by contrast, produces a hypercapnic response—high CO₂ with normal oxygen—without hypoxia.
Nitric Oxide: The Hidden Respiratory Advantage
Nitric oxide is a potent vasodilator, bronchodilator, and antimicrobial gas produced in large amounts in the nasal cavity and paranasal sinuses.
Simply put, nitric oxide is produced in the nasal cavity and sinuses. It supports airway dilation, blood flow, and antimicrobial defense.
Most chronic diseases are associated with a loss of nitric oxide production.
Nasal breathing produces six times more nitric oxide than mouth breathing. Nitric oxide:
- Dilates blood vessels
- Improves ventilation-perfusion matching
- Sterilizes inhaled air
- Acts as a bronchodilator
Humming can increase nasal nitric oxide production by up to 15-fold, dramatically enhancing airway function.
Breath holds after exhalation can further amplify nitric oxide accumulation in the nasal cavity. When you resume breathing, this nitric oxide is carried deep into the lungs and absorbed into the bloodstream.
Sleep, Hormones, and Daytime Breathing Patterns
Breathing patterns during the day directly affect sleep quality. Overbreathing and mouth breathing increase the risk of sleep apnea, especially during REM sleep when muscle tone decreases and the tongue can obstruct the airway.
Poor sleep disrupts hormone production. Elevated cortisol diverts cholesterol away from testosterone and estrogen synthesis. Nasal breathing improves sleep architecture, reduces apnea events, and supports healthier hormone profiles by lowering stress.
Before sleep, slowing the breath to the point of slight air hunger for 15–20 minutes can:
- Increase CO₂
- Dilate blood vessels
- Improve circulation
- Promote drowsiness
- Enhance airway patency
Training the Breath for Performance, Not Just Relaxation
Physical training does not significantly strengthen breathing muscles. Respiratory muscles require specific loading.
Daily nasal breathing, light breath holds, and reduced breathing volume train CO₂ tolerance and diaphragm endurance. This improves:
- Exercise efficiency
- Glycogen preservation
- Fat utilization
- Heart rate control
- Emotional composure
Short-term hyperventilation techniques (e.g., fire breathing, Wim Hof–style breathing) can be useful in specific contexts such as immune activation, but they are not appropriate as baseline breathing patterns and can worsen anxiety in susceptible individuals.
Mouth Breathing, Facial Structure, and Long-Term Health
In addition to shallow chest breaths, lower oxygen delivery, and dry mouth, chronic mouth breathing also alters facial structure—especially when it begins in childhood.
Known as “adenoid face,” this pattern can lead to elongated facial features, recessed jaws, and increased risk of sleep apnea.
The nasal cavity conditions air—slowing, filtering, humidifying, and warming it—before it reaches the lungs. This conditioning improves oxygen uptake by up to 20% compared to mouth breathing.
The Core Principle: Less Is More
Healthy breathing is:
- In and out through the nose
- Driven by the diaphragm
- Light, quiet, and slow
- Gently paused after exhalation
- Effortless and regular
Ancient teachings captured this simply: “The perfect man breathes as if he is not breathing.”
Legend states samurai tested composure by placing a feather under a recruit’s nose. If the feather moved, he was dismissed—an early reminder that calm, controlled breathing is a performance skill.
Reducing breathing volume increases CO₂, improves oxygen delivery, enhances circulation, and stabilizes the nervous system.
Always ask:
- Could I be breathing less?
- Am I breathing through my nose?
Nasal Breathing Research and Law Enforcement Implications
Dr. George Dallam, an exercise physiologist and former competitive cyclist, studied nasal breathing’s effects on athletic performance. His research shows that nasal breathing can match or exceed mouth breathing even at moderate-to-high intensities once athletes adapt. This challenges the assumption that mouth breathing is required for maximal oxygen delivery during hard exertion.
Core findings from Dallam’s research
Oxygen delivery is not the limiting factor. Blood oxygen saturation remains adequate during nasal breathing, even at higher workloads. Performance limitations stem from breathing efficiency and CO₂ tolerance rather than lack of oxygen intake. This aligns with the idea that overbreathing—not under-oxygenation—degrades performance.
Nasal breathing improves breathing efficiency. It slows respiratory rate, increases tidal volume efficiency, and reduces wasted ventilation. Athletes report lower perceived exertion, reduced ventilatory demand at a given workload, and improved metabolic efficiency. In practical terms, less work to breathe means more energy for movement and decision-making.
CO₂ tolerance is a trainable performance variable. Nasal breathing raises carbon dioxide tolerance, which improves oxygen release to tissues via the Bohr effect. Over time, athletes adapt to perform at high intensities without mouth breathing. This reframes CO₂ not as “waste gas,” but as a critical regulator of oxygen delivery.
Heart rate and stress response are lower. Nasal breathing leads to lower heart rates at comparable workloads, reduced sympathetic activation, and greater parasympathetic influence. For high-stress professions, this means better fine motor control, reduced panic breathing, and improved cognitive processing under stress.
An adaptation period is required. Performance may initially drop when switching to nasal breathing. Adaptation typically occurs over weeks rather than days. This explains why nasal breathing fails when people try it once and quit.
Why this matters for law enforcement
From an operational standpoint, these findings suggest that nasal breathing can:
- Improve stress resilience and reduce panic-driven overbreathing
- Maintain cognitive clarity during exertion and enhance recovery between bouts of effort
- Support long-term cardiovascular and respiratory efficiency
In short, better breathing equals better control—not just better endurance.
Complementing modern breathing research
Dallam’s research coincides with Patrick McKeown’s CO₂ tolerance framework, modern stress physiology, and tactical performance models involving heart rate control. His unique contribution lies in testing nasal breathing under real exercise loads, demonstrating its viability in competitive athletes, and quantifying efficiency rather than focusing solely on relaxation.
Practical Applications you can start today
You don’t need complicated routines to get results. The goal is simple: breathe through your nose, slow your breathing down, and build CO₂ tolerance over time.
1) Baseline rule (all day): nasal breathing only
If you catch yourself mouth breathing at rest, you’re likely overbreathing. Keep your mouth closed and breathe quietly through your nose as much as possible throughout the day.
2) Use the physiological sigh as a “real-time reset”
When you feel your stress spike (pre-call, after a high-stress encounter, during adrenaline dump):
- Take two short inhales through the nose
- Follow with one long slow exhale
Do 2–3 rounds and return to calm breathing.
3) Train CO₂ tolerance with light breath holds (easy, not extreme)
Once or twice per day, practice short breath holds after exhalation (comfortable, not max effort). This builds tolerance to CO₂ and improves breathing efficiency over time.
4) During workouts: “nasal as long as possible”
Train nasal breathing during warm-ups and moderate effort. If you have to switch to mouth breathing, that’s fine—then return to nasal breathing as soon as you can. This is how the adaptation happens.
5) Pre-sleep downshift (5 minutes)
Before bed, breathe slowly through your nose and reduce breathing volume slightly (just enough to feel a mild air hunger). This helps shift your nervous system toward recovery and improves sleep quality.
Closing
Research shows that nasal breathing isn’t about breathing less—it’s about breathing better: improving efficiency, stress control, and performance once the body adapts. I’ve been using this breathing approach with myself and other athletes for years. It’s uncomfortable at first—like any meaningful change—but the improvement in performance, stress control, and overall well-being is well worth it.
Avera Health. (2021, October 26). Breath: The Superpower You Use 25,000 Times a Day. Avera Health. Retrieved January 16, 2026, from https://www.avera.org/balance/wellness-and-preventive-care/breath-the-superpower-you-use-25000-times-a-day/
Airly. (n.d.). The composition of inhaled and exhaled air. Airly. Retrieved January 16, 2026, from https://airly.org/en/the-composition-of-inhaled-and-exhaled-air/
StatPearls. (2023, August 8). Physiology, Bohr effect. StatPearls. Retrieved January 16, 2026, from https://www.ncbi.nlm.nih.gov/books/NBK541105/
Current Opinion in Anaesthesiology. (2019, October). Hyperventilation in neurological patients: from physiology to outcome evidence. Current Opinion in Anaesthesiology. Retrieved January 16, 2026, from https://pubmed.ncbi.nlm.nih.gov/31211719/
Frontiers in Neurology. (2017, July 17). Hyperventilation therapy for control of posttraumatic intracranial hypertension. Frontiers in Neurology. Retrieved January 16, 2026, from https://www.frontiersin.org/articles/10.3389/fneur.2017.00250/full
Journal of Electromyography and Kinesiology. (2015, April 6). Diaphragmatic amplitude and accessory inspiratory muscle activity in nasal and mouth‑breathing adults: A cross‑sectional study. Journal of Electromyography and Kinesiology. Retrieved January 16, 2026, from https://pubmed.ncbi.nlm.nih.gov/25900327/
BMC Sports Science, Medicine and Rehabilitation. (2024, February 9). Nose vs. mouth breathing – acute effect of different breathing regimens on muscular endurance. BMC Sports Science, Medicine and Rehabilitation. Retrieved January 16, 2026, from https://pmc.ncbi.nlm.nih.gov/articles/PMC10858538/
CBS San Francisco. (2020, September 10). S.F. science journalist’s research underscores importance of proper breathing. CBS San Francisco. Retrieved January 16, 2026, from https://www.cbsnews.com/sanfrancisco/news/s-f-science-journalists-research-underscores-importance-of-proper-breathing/
Bond University. (2023, October 25). Is humming healthy? Mmm, here’s what the evidence says. Bond University. Retrieved January 16, 2026, from https://bond.edu.au/news/humming-healthy-mmm-heres-what-evidence-says
American Journal of Respiratory and Critical Care Medicine. (2005, April 15). ATS/ERS recommendations for standardized procedures for the online and offline measurement of exhaled lower respiratory nitric oxide and nasal nitric oxide, 2005. American Journal of Respiratory and Critical Care Medicine. Retrieved January 16, 2026, from https://pubmed.ncbi.nlm.nih.gov/15817806/
Frontiers in Public Health. (2024, December 12). Adenoid facies: a long‑term vicious cycle of mouth breathing, adenoid hypertrophy, and atypical craniofacial development. Frontiers in Public Health. Retrieved January 16, 2026, from https://www.frontiersin.org/articles/10.3389/fpubh.2024.1494517/full
UCLA Newsroom. (2016, February 8). UCLA and Stanford researchers pinpoint origin of sighing reflex in the brain. UCLA Newsroom. Retrieved January 16, 2026, from https://newsroom.ucla.edu/releases/ucla-and-stanford-researchers-pinpoint-origin-of-sighing-reflex-in-the-brain
