Performance optimization at the highest levels comes down to fractions — fractions of a second, fractions of a percentage point in recovery, marginal gains stacked until they aren't marginal anymore. Athletes and their support teams spend enormous resources on nutrition, training load, sleep tech, and supplementation.
And then most of them breathe through their mouths.
Nasal breathing is one of the least discussed and most mechanistically interesting levers in athletic performance and recovery. The science is still evolving, but what exists is compelling enough that top coaches, sports scientists, and wellness-forward athletes are paying serious attention.
The Nitric Oxide Connection
The most important mechanism is one most people have never heard of.
Your nasal passages and paranasal sinuses continuously produce nitric oxide (NO), a signaling molecule with significant effects on vascular and respiratory function. When you breathe through your nose, nitric oxide is delivered directly into the lungs with every inhalation. It acts as a vasodilator, relaxing blood vessels and improving circulation. It enhances ventilation-perfusion matching, the efficiency with which oxygen in the lungs actually crosses into the bloodstream. It supports mucociliary clearance and regulates blood flow throughout the pulmonary system.
When you breathe through your mouth, you bypass the sinuses entirely. No nitric oxide. Every breath delivers air without this compound, and over time, especially during exercise and sleep, that difference accumulates.
A 2025 study published in Frontiers in Physiology confirmed that nasal breathing facilitates the endogenous production and delivery of nitric oxide, and that this mechanism has been shown to improve both ventilation-perfusion matching and pulmonary oxygen uptake. Studies have indicated that nasal breathing increases oxygen uptake efficiency by up to 18% compared to mouth breathing, not because more air is entering, but because the air that does enter is processed more effectively.
Nasal breathing increases oxygen uptake efficiency by up to 18% compared to mouth breathing.
Recovery: Where the Evidence Is Clearest
If the performance data during exercise is nuanced, the recovery data is more definitive.
A 2025 study published in Sports examined nasal versus oral breathing during anaerobic exercise in 49 healthy participants. The findings: while breathing mode did not significantly impact peak power output during exercise, nasal breathing resulted in significantly faster and greater post-exercise muscle recovery. Muscle reoxygenation was both quicker and more complete in nasal breathers after exhaustive exercise.
This aligns with the broader nitric oxide mechanism: improved vasodilation means better blood flow to recovering muscle tissue, more efficient waste removal, and faster return to baseline. For athletes whose performance depends on the speed of recovery between sessions, between plays, or between training days, this matters.
The same study found that perceived exertion was significantly higher in oral breathers, even when objective power output was comparable. That subjective experience of effort has real implications for training quality and training longevity.
What Happens at Night
The performance conversation tends to focus on what happens during training. But the most impactful window for nasal breathing in athletes may actually be sleep.
Deep, restorative sleep is when the body does the work of adaptation: repairing muscle tissue, consolidating motor patterns, regulating anabolic hormones. All of that is compromised when sleep is fragmented. And mouth breathing during sleep is one of the most common, underrecognized causes of sleep fragmentation.
When the mouth falls open during sleep, airway resistance increases, the soft tissues of the throat are more likely to vibrate or partially collapse, and the restorative depth of sleep is compromised. For athletes whose entire recovery architecture depends on the quality of sleep, this is not a small variable.
Mouth breathing also dries the oral environment overnight, disrupting the oral microbiome and reducing immune defense. For athletes in heavy training, when systemic immune function is already taxed, this is an additional load the body doesn't need.
Nasal breathing during sleep, specifically keeping the lips sealed, activates the parasympathetic nervous system, promotes the production of nitric oxide, and supports the continuous, uninterrupted sleep that genuine recovery requires.
Why This Is Reaching Elite Sport
The conversation has moved beyond biohacking circles and into professional locker rooms. Manchester City and Norway forward Erling Haaland has spoken publicly about taping his mouth shut at night to encourage nasal breathing, telling podcast hosts KSI and Logan Paul on Impaulsive that "sleep is the most important thing in the world" and describing it as one of several small, consistent habits that compound over time.
The broader conversation has been growing across high-performance contexts. Andrew Huberman, Matt Walker, and Dhru Purohit have all explored nasal breathing and mouth taping with significant audiences. James Nestor's New York Times bestseller Breath brought the underlying science to millions of readers. And athletes across professional sports, particularly in high-contact, high-recovery-demand sports, have begun incorporating nasal breathing practices and sleep optimization tools into their routines.
VIO2 has been featured in Goop, Vogue, ELLE, People, Good Morning America, Glamour, WWD, and The Strategist, a reflection of the brand's position at the intersection of medical credibility and wellness mainstream. The brand was co-founded by Dr. Vincent Ip, whose clinical focus on airway health and sleep disorders informs every aspect of VIO2's design and positioning.
The Practical Application
For most people, including athletes, nasal breathing during sleep is the most accessible entry point. It requires no skill acquisition, no equipment beyond the tape itself, and no willpower in the moment because it happens while you're asleep.
VIO2's patented partial-coverage design was built to make this habit frictionless. Two ways to wear, hypoallergenic medical-grade adhesive, breathable cotton fabric, and a partial-coverage shape that allows airflow even when sealed, so there's never a feeling of restriction. It was designed by a doctor, tested clinically, and built for nightly, long-term use.
Key Takeaway
Nasal breathing increases nitric oxide delivery and oxygen uptake efficiency, speeds post-exercise muscle recovery, and supports deeper, more restorative sleep, the foundation of every recovery protocol. It requires no equipment beyond consistent lip seal, day and night.
The athletes already doing this aren't waiting for a landmark study. They're operating on the same logic that drives every other marginal gain: the mechanism is sound, the downside is essentially zero, and the upside compounds over time.
The Bottom Line
Nasal breathing won't replace training. It won't substitute for nutrition, coaching, or the other fundamentals of athletic development. But for athletes already doing everything right, the breath is one of the last overlooked variables, and it's one that's operating 24 hours a day, 20,000 breaths at a time.
The mechanism is real. The recovery data is compelling. And the intervention is as simple as keeping your mouth closed at night.
VIO2 is the original doctor-created, partial-coverage mouth tape, made in the USA and free of PFAS. As with any recovery or sleep tool, consult your physician if you have underlying respiratory conditions.