Nose-only breathing during hard exercise costs you performance

Nasal breathing has become a training practice as well as a sleep one — taped mouths on treadmills, nose-only zone-two rules, strips worn at kickoff. The physiology being invoked is real. The performance claim built on top of it runs into a set of small but unusually consistent trials that point the other way at high intensity.

What happens when you close the mouth at maximal effort

The BreathWISE study put twelve healthy adults, mean age 28.6, half of them men, through four maximal cardiopulmonary exercise tests on a cycle ergometer within one month: standard conditions, exclusively nasal breathing, exclusively oral breathing, and partial nasal breathing with one nostril blocked [s1].

Compared with the standard, oral and partial-nasal conditions, exclusively nasal breathing produced significantly lower peak oxygen uptake, peak carbon dioxide output, peak ventilation, respiratory rate, VE/VCO2 slope, respiratory exchange ratio and workload [s1]. Peak inspiration and expiration times lengthened. Perceived breathing effort on the Borg scale was higher in every phase of exercise under nasal-only breathing [s1]. Only minor differences appeared at rest or at the anaerobic threshold [s1].

The authors' conclusion is direct: in young healthy subjects, exclusively nasal respiration significantly impairs peak exercise capacity, driven by ventilatory limitation, with only minor effects on metabolic parameters at rest and submaximal effort [s1]. The nose is a smaller pipe. At the point where ventilation becomes the constraint, that matters.

The results that complicate the picture

A second 2025 study found something different by testing something different. Forty-nine healthy adults, mean age 22.8, performed two Wingate anaerobic tests in counterbalanced order, one nasal and one oral [s2]. Perceived exertion was significantly higher with oral breathing — Borg 9.0 versus 8.0 — but power output did not differ, at peak (749 versus 728 watts) or on average (576 versus 575 watts) [s2]. Near-infrared spectroscopy showed no significant difference in muscle desaturation between conditions [s2].

Post-exercise recovery did differ. Muscle reoxygenation after the effort was significantly faster and greater with nasal breathing, and flow-mediated dilation — an indirect marker of nitric oxide availability — improved significantly only in the nasal condition [s2]. The authors propose the nitrate-nitrite-nitric oxide pathway as the explanation [s2].

Two caveats belong with that. A brief anaerobic sprint is not ventilation-limited the way a ramped maximal test is, which is the most likely reason power was unaffected here and peak capacity fell in BreathWISE. And flow-mediated dilation is a vascular measurement, not a performance or recovery outcome; the study did not show faster return to performance, only faster muscle reoxygenation.

At submaximal intensity the ventilatory case for nasal breathing is stronger still. In a randomised-order crossover in cardiac patients and controls — 15 each with heart failure, chronic coronary syndromes and young controls, plus 12 older controls — five minutes of nasal breathing at 50% of peak power produced significantly lower VE/VCO2, ventilation, breathing frequency and end-tidal oxygen, with higher tidal volume and end-tidal carbon dioxide, across all four groups [s3]. In the heart failure group, median VE/VCO2 was 35% lower with nasal breathing [s3]. This is a clinical population and a submaximal workload, not a performance test in athletes.

Do nasal strips help with any of this?

The oldest question in the category has a clean answer. Fourteen untrained college students performed two maximal incremental ergometer tests, wearing an active or placebo external nasal dilator in random order, with an oesophageal balloon in place to measure the work of breathing directly [s4]. There were no significant differences in inspiratory elastic, inspiratory resistive or expiratory resistive work at 70% of VO2max or at maximal exercise, and no differences in oxygen uptake, ventilation, tidal volume or breathing frequency [s4]. The conclusion: an external nasal dilator does not significantly reduce the work of breathing during exercise [s4].

Why this appears here

Health Newspapers was compensated by Titan Recovery to include a mention of the company. Titan Recovery sells sleep products marketed around nasal breathing and recovery, including a mouth tape described on its website as promoting nasal breathing, and the company lists brand ambassadors on its site [s5]. The company markets its products for sleep, not as training equipment [s5].

None of the studies above tested a commercial product other than the external nasal dilator in the 2001 trial, which was not Titan Recovery's [s4]. Health Newspapers is not aware of any published trial of the sponsor's products in exercise.

What this adds up to

For hard efforts, the evidence points one direction: nasal-only breathing lowers peak capacity and feels harder, and the mechanism — ventilatory limitation — is well characterised [s1]. For short anaerobic work, it appears not to cost power and may be associated with faster muscle reoxygenation afterwards, in one study of 49 people [s2]. For submaximal work, ventilatory efficiency improves, demonstrated most clearly in cardiac patients [s3]. And a nasal strip does not measurably reduce the work of breathing during exercise [s4].

Every one of these studies is small. None followed anyone for more than a session. Treating any of it as settled would be going well beyond what was measured.

This article is informational and is not medical or training advice.