top of page
Search

A Critical Evaluation of Nasal versus Oral Breathing

Updated: May 25

Physiological Mechanisms and Implications for Endurance Performance


Breathing is a fundamental and trivial physiological process that underpins human life. At

its most fundamental level, breathing serves the primary function of gas exchange, involving

the inhalation of oxygen, its diffusion from the lungs into the bloodstream and subsequently

into the cells, as well as the removal of carbon dioxide from the body via the reverse

pathway. This simple process of gas exchange occurs approximately 25,000 times per day

and forms the basis for the survival of the human organism. While the conscious control of

breathing has long been an integral component of ancient cultures and various philosophies,

breathing itself is primarily an automatic function to which humans have likely devoted little

conscious attention for most of human history. However, this perspective has shifted in recent

years. Individuals today are increasingly exposed to information on various breathing

techniques aimed at reducing stress, prolonging lifespan, or enhancing physical

performance. Nevertheless, it has become evident that breathing is far more complex than a

simple process of gas exchange occurring thousands of times per day. Research in this area

has expanded considerably over the past few decades, accompanied by an increasing focus

on examining how breathing influences physical performance. The following text aims to

provide a critical evaluation of how different breathing strategies—particularly nasal versus

oral breathing—contribute to distinct short- and long-term physiological adaptations that may

influence endurance performance, with a particular emphasis on aerobic capacity.


It is well established that nasal breathing confers several physiological advantages over

oral breathing. The initial benefit arises in the nasal passages, where the turbinates create a

large, complex surface area. This structure functions to warm and humidify inspired air

before it reaches the lungs, thereby reducing respiratory tract irritation and helping to prevent

airway cooling that may trigger bronchoconstriction (Morton & Sexton, 1995). Beyond this primary function, the choice of breathing route also has systemic effects. For instance, acute

nasal breathing has been shown to increase parasympathetic nervous system activity,

leading to higher heart rate variability and reduced diastolic blood pressure (Watso, 2023).

Furthermore, chronic oral breathing, particularly during sleep, is strongly associated with

adverse health outcomes. It is a key feature of sleep-disordered breathing (Fitzpatrick, 2003),

which has been linked to insulin resistance (Punjabi, 2004) and alterations in the oral

microbiome (Zhang et al., 2021).

Over the past three decades, a substantial body of research has investigated the effects

of nasal versus oral breathing on physiological adaptations relevant to endurance

performance. Observational studies indicate that most athletes switch to oral breathing

during high-intensity exercise, a strategy driven by the need for higher ventilation rates

(Saibene et al., 1978; Niinimaa, 1983). This phenomenon is explained by fundamental

differences in breathing mechanics, as the nasal passages account for at least 50% of total

airway resistance (McNicholas, 2008), resulting in a significantly lower breathing frequency

compared to oral breathing at the same exercise intensity (Eser et al., 2024). The ventilatory

restrictions imposed by nasal breathing during exercise appear to have limiting effects for

performance, as oral breathing may be necessary to achieve maximal oxygen consumption

(VO2max) (Morton & Sexton 1995). Accordingly, at high exercise intensities, nasal breathing

may impair the ability to meet the elevated ventilatory demands associated with strenuous

physical activity (Dallam & Kies, 2020; Mapelli et al., 2025), potentially leading to reductions

of up to 35% in maximal ventilation (Morton & Sexton, 1995). In contrast, oral breathing

facilitates greater air exchange (LaComb et al., 2017), resulting in an approximately 10%

higher VO2max and an 8.4% increase in maximal running velocity during a graded exercise

test compared to nasal breathing (Morton & Sexton, 1995). Accordingly, nasal breathing may

lead to various direct consequences that impair physical performance near maximal effort

(Morton & Sexton, 1995; Garner et al., 2011; LaComb et al., 2017; Mapelli et al., 2025).

It is important to note, however, that these studies investigated populations who were not

specifically adapted to nasally restricted breathing.


However, a recent study by Dallam et al. (2018) investigated the effects of the two

different breathing patterns in recreational runners who were already adapted to nasal

restricted breathing patterns during running. Dallam et al. (2018) compared the effects of

nasal-only and oral-only breathing in recreational runners with a minimum of six months of

prior nasal breathing training across two different tests. The first was a graded exercise test

to determine VO2max. The second was a high-intensity run performed for six minutes at 85% of the maximal running velocity achieved during the VO2max test. In contrast to previously mentioned studies, Dallam et al. (2018) demonstrated that comparable peak work rates (i.e., running velocity) and maximal oxygen consumption during a graded exercise test can be achieved under nasal breathing conditions as under oral breathing. Accordingly, no

significant differences in maximal performance were observed, as VO2max, time to

exhaustion, and peak lactate levels remained similar between the two breathing conditions.

This represents a critical finding, as it suggests that, with prior adaptation, athletes may be

able to achieve their maximal aerobic capacity using nasal breathing. Notably, participants

were able to maintain these performance parameters despite exhibiting lower total

ventilation, likely resulting from the ventilatory limitations imposed by nasal breathing. This

ultimately suggests that runners may be able to increase oxygen uptake per breath when

breathing through the nose, as evidenced by a significant decrease in the fractional

concentration of expired oxygen under nasal breathing conditions, indicating that more

oxygen was extracted from the air and absorbed into the bloodstream with each breath

(Dallam et al., 2018). Lundberg et al. (1996) attribute this superior gas exchange efficiency

primarily to the inhalation of nitric oxide which is produced in upper airways called paranasal

sinuses and subsequently carried to the lungs during nasal breathing. Nitric oxide plays a

key biochemical role by acting as a pulmonary vasodilator, which optimizes the matching of

ventilation to perfusion in the alveoli. This improved efficiency was shown to increase arterial

oxygen tension by up to 10%, therefore being a biochemical advantage for oxygen uptake, a

mechanism that is completely bypassed during oral breathing.

Interestingly, Nalbandian et al. (2017) investigated the effects of a reduced breathing rate

during a high-intensity incremental exercise test in cyclists while maintaining oral breathing.

In this study, participants reduced their breathing rate from 60 to 30 breaths per minute,

accompanied by an increase in tidal volume. The reduced breathing rate did not limit

performance, as maximal work capacity and maximal oxygen uptake were maintained. This

suggests that it is not necessarily the breathing pattern itself, but rather a reduced breathing

rate, that serves as the primary driver of respiratory efficiency and, consequently, improves

oxygen uptake per breath. Nalbandian et al. (2017) attribute this to the increased time

available for gas diffusion during each breath at lower breathing frequencies, as well as to a

reduction in so-called “dead space ventilation” (Barrett et al., 2019), defined as the volume of

air remaining in the conducting airways that does not participate in gas exchange

(approximately 150 mL per breath in the average adult). Accordingly, a reduced respiratory

rate decreases the total volume of non-participating inhaled air (Dallam et al., 2018), which

may confer a mechanical efficiency advantage.


An important consideration is that measured performance output—assessed directly

through metrics such as running velocity—when comparing nasal and oral breathing remains

unchanged in these studies. Therefore, it could be argued that improvements in breathing

efficiency resulting from a reduced breathing frequency may be of limited relevance, as

overall performance remains unaffected.

However, depending on an athlete’s performance level, the respiratory muscles can consume

up to 15% of total oxygen uptake. Increased respiratory muscle fatigue may additionally

reduce blood flow to the working muscles, particularly in the lower limbs. Over time, this may

ultimately lead to a decline in performance (Harms et al., 1997; Harms, 2015).

Furthermore, breathing frequency is strongly correlated with an individual’s rate of

perceived exertion and may be more closely associated with it than either heart rate or blood

lactate concentration (Chen, 2002; Nicolò et al., 2016). This is a crucial finding, as a lower

breathing frequency may inherently reduce the perception of effort at a given workload.

Furthermore, by reducing minute ventilation, a slower breathing pattern may increase arterial

carbon dioxide tension, as less CO2 is expelled during exhalation. This enhances the Bohr

effect, whereby elevated CO2 concentrations in the capillaries promote the dissociation of

oxygen from haemoglobin, thereby improving oxygen delivery to the working tissues (Eser et

al., 2024). Long-term adaptation to this breathing pattern may also induce favourable

changes in respiratory control. Chronic exposure to slightly higher CO2 levels can reduce the

chemosensitivity of the central respiratory centres, effectively increasing an individual's

tolerance to CO2 (Walterspacher, 2011). This adaptation allows for a more efficient breathing

pattern to be maintained even during strenuous exercise (Dallam et al., 2018).


Finally, it must be noted that independent of breathing frequency, the inherent benefits of

nasal breathing—such as air conditioning, humidification, and the filtering of particulates—

provide a protective effect on the airways that is absent during oral breathing.

While nasal breathing offers significant physiological benefits, its inherent airflow

resistance presents a potential performance limitation as exercise intensity increases. For

non-adapted individuals, this ventilatory constraint can impair performance during maximal

efforts compared to oral breathing. However, the research strongly suggests that the

respiratory system is trainable. After a sufficient adaptation period, athletes may be able to

perform at all intensities using exclusive nasal breathing without compromising maximal

oxygen uptake, while simultaneously benefiting from superior physiological economy and

ventilatory efficiency (Dallam et al., 2018). For non-adapted individuals, however, exclusive

nasal breathing is only sustainable up to a submaximal intensity threshold, beyond which

performance declines.

A key principle emerging from the evidence is that breathing pattern itself is a primary

determinant of efficiency, regardless of the breathing route. A lower breathing frequency is

physiologically more efficient as it increases the time available for gas diffusion and reduces

the proportion of wasted dead-space ventilation. Furthermore, breathing frequency is a

significant modulator of perceived exertion; a lower frequency can cause an equivalent

workload to be perceived as less strenuous.

Based on these findings, athletes should be encouraged to practice exclusive nasal

breathing. This strategy promotes a more efficient, low-frequency breathing pattern, which

may enhance long-term CO2 tolerance, improve physiological economy, and reduce the

subjective perception of effort. Nevertheless, forcing nasal breathing in non-adapted athletes

is likely to be detrimental to performance during high-intensity efforts. These athletes should

allow the natural switch to oral breathing to occur as intensity dictates. Athletes who wish to

use nasal breathing at high intensities must commit to a dedicated and extended period of

adaptation. Finally, it is important to note that, independent of breathing pattern, a reduced

breathing frequency during exercise may generally be advantageous.





References


Barrett, K. E., Barman, S. M., Boitano, S., & Brooks, H. L. (2019). Ganong's review of medical

physiology (26th ed.). McGraw-Hill Education.

Chen, M. J., Fan, X., & Moe, S. T. (2002). A meta-analysis of the Borg ratings of perceived

exertion scale: Validity and reliability. Journal of Sports Sciences, 20(11), 873–

Dallam, G. M., & Kies, B. (2020). The effect of nasal breathing versus oral and oronasal breathing

during exercise: A review. Journal of Sports Research, 7(1), 1–

Dallam, G. M., McClaran, S. R., Cox, D. G., & Foust, C. P. (2018). Effect of nasal versus oral

breathing on VO2max and physiological economy in recreational runners following an

extended period spent using nasally restricted breathing. International Journal of

Kinesiology and Sports Science, 6(2), 22–29. https://doi.org/10.7575/aiac.ijkss.v.6n.2p.22

Eser, P., Stössel, M., Gygax, L., Stoller, M., Mivelaz, Y., Trachsel, L. D., Wilhelm, M., & Saner, H.

(2024). Nasal versus oral breathing during low-intensity exercise in patients with heart

9

disease: A randomized crossover trial. European Journal of Preventive

Cardiology, 31(Supplement_1), zwae064-022. https://doi.org/10.1093/eurjpc/zwae064.022

Fitzpatrick, M. F., McLean, H., Urton, A. M., & Tan, A. (2003). Effect of nasal or oral breathing on

patterns of sleep-disordered breathing. European Respiratory Journal, 22(5), 827–

Garner, D. P., Dudgeon, W. D., & McDivitt, E. J. (2011). The effects of nasal and oral breathing on

verbal and cognitive task performance. International Journal of Kinesiology and Sports

Science, 2(3), 27-32.

Harms, C. A. (2015). Breathing in exercise: Battle of the sexes. The Journal of

Harms, C. A., Babcock, M. A., McClaran, S. R., Pegelow, D. F., Nickele, G. A., Nelson, W. B., &

Dempsey, J. A. (1997). Respiratory muscle work compromises leg blood flow during

maximal exercise. Journal of Applied Physiology, 82(5), 1573–

LaComb, C. O., Tandy, R. D., Lee, S. P., Young, J. C., & Navalta, J. W. (2017). The effects of oral

versus nasal breathing on gas exchange and perceived exertion during various levels of

submaximal activity. International Journal of Exercise Science, 10(4), 557–565.

Lundberg, J. O., Weitzberg, E., Lundberg, J. M., & Alving, K. (1996). Inhaled nitric oxide from the

nose can reach the lungs and increase arterial oxygen tension. Nature Medicine, 2(8),

Mapelli, M., Salvioni, E., Mattavelli, I., Grilli, G., Zerboni, G., Nava, A., Capra, N., Galotta, A.,

Biroli, M., Bellini, G., & Agostoni, P. (2025). Nasal vs. oral BREATHing WIn Strategies in

healthy individuals during cardiorespiratory Exercise testing (BreathWISE). PLOS ONE,

McNicholas, W. T. (2008). The nose and OSA: Cause or consequence?. Current Opinion in

Pulmonary Medicine, 14(6), 547–553. https://doi.org/10.1097/MCP.0b013e328315a099

10

Morton, E. P., & Sexton, W. L. (1995). Comparison of maximal oxygen consumption with oral and

nasal breathing. European Journal of Applied Physiology and Occupational

Physiology, 71(2), 183–186. https://doi.org/10.1007/BF00238557

Nalbandian, M., Radák, Z., Taniguchi, J., & Masaki, T. (2017). How different respiratory rate

patterns affect cardiorespiratory variables and performance. International Journal of

Exercise Science, 10(3), 433–442.

Nicolò, A., Marcora, S. M., & Sacchetti, M. (2016). Respiratory frequency is strongly associated

with perceived exertion during time trials of different duration. Journal of Sports

Niinimaa, V. (1983). Oronasal partition of respiratory airflow. Respiration Physiology, 53(1), 123–

Punjabi, N. M., Sorkin, J. D., Katzel, L. I., Goldberg, A. P., Schwartz, A. R., & Smith, P. L. (2004).

Sleep-disordered breathing and insulin resistance in middle-aged and overweight

men. American Journal of Respiratory and Critical Care Medicine, 169(4), 501–

Saibene, F., Mognoni, P., & Lafortuna, C. (1978). Oronasal breathing during exercise. Pflügers

Archiv European Journal of Physiology, 378(1), 65–

Walterspacher, S., Scholz, T., Teschler, H., & Sorichter, S. (2011). CO2-reactivity in elite breath-

hold divers. Respiratory Physiology & Neurobiology, 178(2), 263–

Watso, J. C., Stickford, J. L., & Badrov, M. B. (2023). Acute nasal breathing lowers diastolic blood

pressure and increases parasympathetic contributions to heart rate variability in

normotensive individuals. American Journal of Physiology-Regulatory, Integrative and

Comparative Physiology, 324(2), R256–R264. https://doi.org/10.1152/ajpregu.00213.2022

Zhang, Y., Li, Y., Zhang, J., & Li, H. (2021). The oral microbiome in obstructive sleep

apnea. Sleep Medicine Reviews, 59, 101520. https://doi.org/10.1016/j.smrv.2021.101520

 
 
 

Comments

bottom of page