Running with your mouth closed often seems counterintuitive, as most people instinctively gasp for air when exertion increases. Nasal breathing involves taking in and releasing air exclusively through the nostrils, even as physical demands rise. This technique is gaining attention among runners seeking to optimize their physiological response to endurance training. While mouth breathing is commonly perceived as necessary for sufficient oxygen intake, evidence suggests that using the nose offers distinct advantages for both air quality and athletic efficiency.
The Role of Nasal Passages in Air Preparation
The nasal passages are designed to prepare inhaled air before it reaches the lungs, a function the mouth cannot replicate. Inhaling through the nose provides immediate conditioning by filtering out foreign particles like dust, pollen, and environmental pollutants using the nasal hairs and mucous lining. This filtration reduces the burden on the respiratory system and helps prevent irritation in the lower airways.
The internal nasal structures also warm and humidify the incoming air, bringing it close to body temperature. This conditioning protects the lungs from the drying and cooling effects of breathing cold, dry air, which often triggers exercise-induced bronchoconstriction. The nose thus supports a smoother, less stressful gas exchange process within the alveoli.
A benefit of nasal breathing is the production of Nitric Oxide (NO) in the paranasal sinuses. This gas is drawn into the lungs with the inhaled air, where it acts as a vasodilator, causing blood vessels to widen. The vasodilation improves blood flow and enhances the efficiency of oxygen uptake by the blood, delivering more oxygen to working muscles for the same volume of air.
Improving Running Economy and Efficiency
Consistent practice of nasal breathing during submaximal running can lead to measurable improvements in physiological economy, which refers to using less energy for the same output. The slight restriction of the nasal passages results in a slower, deeper breathing pattern, which allows for increased retention of carbon dioxide (CO2) in the blood. Slightly higher CO2 levels trigger the Bohr effect, signaling hemoglobin to release its bound oxygen more readily to the tissues.
This increased tolerance to CO2 effectively trains the body to manage the sensation of “air hunger,” reducing the urge to hyperventilate and helping to stabilize the heart rate at submaximal efforts. Runners who adapt to this breathing style experience a lower overall ventilation rate for a given running intensity, meaning they spend less energy on the act of breathing itself. Reducing the work of the respiratory muscles frees up energy that can be directed toward locomotion, contributing to better endurance.
The reduced physiological stress associated with nasal breathing translates to a lower perceived exertion (RPE) during steady-state runs. By promoting a slower, more rhythmic breathing pattern, the technique engages the body’s parasympathetic nervous system, which is associated with rest and recovery. This shift helps maintain a calmer state, making the run feel less demanding even as the athlete maintains the same pace.
Practical Steps for Transitioning to Nasal Breathing
The initial transition to nasal running requires a significant reduction in pace to accommodate the restricted airflow. Runners should begin practicing at a very slow, conversational pace, often referred to as Zone 2, where they can comfortably maintain the nose-only breathing pattern without strain. This low-intensity foundation is necessary to allow the respiratory system to adapt to the new workload.
The initial feeling of air restriction, or “air hunger,” is normal and should be managed by slowing down further, not by opening the mouth. Consistency is more important than intensity in the early stages; some experts suggest starting with short intervals of 30 to 60 seconds of nasal breathing interspersed with recovery periods. Gradually increasing the duration of the nasal breathing segments over several weeks helps build tolerance.
Another practical technique is maintaining proper tongue posture by gently resting the tongue against the roof of the mouth, just behind the front teeth. This positioning helps seal the mouth and encourages a deeper, diaphragmatic breath rather than shallow chest breathing. Runners should focus on a rhythmic pattern, coordinating inhales and exhales with their foot strikes to regulate the breath and maintain consistency.
Limits to Nasal Running
While highly beneficial for low- to moderate-intensity running, nasal breathing has limitations when exercise intensity increases. The nasal passages cannot physically accommodate the massive volume of air required during high-intensity efforts, such as sprinting or running at maximal aerobic capacity (Zone 4 or 5). When the body’s ventilation demand surpasses approximately 35 to 40 liters of air per minute, the runner will instinctively switch to mouth breathing to avoid a feeling of suffocation.
Forcing nasal breathing during these maximal efforts will create undue stress and compromise performance, as the body requires the maximum possible air exchange to fuel the anaerobic work. Nasal breathing should be viewed as a tool for training and recovery, not a requirement for all running speeds. Physical obstructions also make the technique impractical, including severe congestion, seasonal allergies, or a diagnosed structural issue like a deviated septum.