How breathing affects health and performance with Brian MacKenzie

Originally published on August 10, 2022

Breathing affects stress, sleep quality, and exercise tolerance, and this article breaks down how to train it with more intention. In Episode 184 of the WHOOP Podcast, human performance and breathing expert Brian MacKenzie, founder and CEO of Shift and president and co-founder of The Health & Human Performance Foundation, explains why breath is one of the fastest ways to influence state, pacing, and recovery.

MacKenzie has spent years coaching athletes, executives, and endurance performers, and the conversation centers on a simple idea: breathing is automatic, but it is also trainable. The episode covers hypoxia, mouth versus nasal breathing, what efficient breathing looks like, and how to build a practice that fits real life.

To listen to episode 184 in full, head to the WHOOP Podcast on YouTube.

How can breathing affect stress, sleep, and performance?

Breathing changes physiology quickly because it sits at the intersection of the nervous system, attention, and movement. A slower, more controlled pattern can help bring arousal down, while faster breathing can raise alertness and effort.

That is the frame MacKenzie brings to Episode 184 of the WHOOP Podcast. He treats breathing as a skill that influences how you respond to training, how settled you feel before sleep, and how much tension you carry through the day. In practical terms, breath affects whether you stay composed under load or drift into a stressed state long before the work itself demands it.

Published research helps explain why this matters. In Brief Structured Respiration Practices Enhance Mood and Reduce Physiological Arousal, participants practiced breathing for five minutes a day over one month. All three breathing exercises improved mood and reduced physiological arousal, and cyclic sighing produced the largest drop in respiratory rate. WHOOP also summarized those findings in Understanding the most effective breathwork techniques.

For WHOOP members, this is where breathing stops being abstract. A calmer breathing pattern may line up with steadier Sleep, better next-day Recovery, or a lower nightly respiratory rate over time. A rushed pattern can show up as the opposite, especially when it becomes your default rather than a temporary response to hard work.

If you want to hear MacKenzie unpack breathing as a performance input, listen to the full episode on Spotify.

What you should take away

• Breathing is a fast way to influence nervous system state, perceived stress, and training control.
• Short daily breathing practices can improve mood and lower physiological arousal.
• WHOOP data becomes more useful when you connect breath habits to Sleep, Recovery, and respiratory rate trends.

How does hypoxia fit into breathing training?

Hypoxia means reduced oxygen availability, and it raises the demand on your breathing system. In training, that can come from altitude, altitude simulation, or drills that limit airflow long enough to change how urgently you feel the need to breathe.

From that broad view of breathing, MacKenzie moves into hypoxia because it forces awareness. When oxygen pressure drops, pacing errors show up faster, panic rises faster, and inefficient breathing becomes harder to ignore. That is part of the appeal, but it is also why context matters. Hypoxic work adds stress, so it belongs inside a clear plan rather than as a sensation people chase for its own sake.

For most people, the useful lesson is simpler than formal hypoxic training. Building tolerance to discomfort starts with better mechanics during easy work, fuller exhales, and learning how quickly you default to upper chest breathing when demand rises. Once those basics are in place, harder breathing drills can become more informative instead of more chaotic.

WHOOP can add guardrails here. If Recovery is already low, Sleep is trending down, and respiratory rate is elevated, a high-stress breathing session may add load on top of load. If those signals are stable, you have more room to experiment with breathing-specific work and judge the response over the next several days.

If you want to hear MacKenzie go deeper on why hypoxia changes effort and awareness, watch the full episode on YouTube.

What you should take away

• Hypoxia increases breathing demand and makes pacing and tension harder to hide.
• Breathing drills work better when basic mechanics are already under control.
• Recovery context matters before adding another stressor, including breathing-specific stress.

How does mouth breathing change sleep and training?

Mouth breathing has a role during hard efforts, but default mouth breathing at rest, during easy exercise, or during sleep can create a less controlled pattern. Nasal breathing supports filtration, humidification, and pace regulation, and it often helps keep easy work easy.

That is why MacKenzie spends time on both the physiological impact of mouth breathing and the benefits of nasal breathing. The goal is not to force nasal breathing in every setting. The goal is to widen the range where you can stay calm, efficient, and rhythmic before intensity truly demands a different strategy.

This is also where respiratory rate becomes useful. WHOOP research discussed in Episode 67 of the WHOOP Podcast and Episode 102 of the WHOOP Podcast found that respiratory rate tends to stay very stable from night to night in healthy conditions. Because the metric is usually steady, changes can stand out when congestion, illness, altitude, alcohol, or other stressors affect how you breathe during sleep.

If you want more context on nasal breathing itself, Episode 221 of the WHOOP Podcast extends the same conversation through the lens of author James Nestor. Together, those episodes make a practical point: breathing route is a behavior, and behaviors leave patterns.

If you want to hear MacKenzie unpack mouth breathing and nasal breathing in training, listen to the full episode on Spotify.

What you should take away

• Nasal breathing can help regulate pace and keep low-intensity work more controlled.
• Mouth breathing becomes more useful as intensity rises, especially when output truly demands it.
• Nightly respiratory rate is worth watching because it is usually stable when health and environment are stable.

What does efficient breathing actually look like?

Efficient breathing is quiet, rhythmic, and matched to the task in front of you. At rest and during easy work, it usually means less neck and shoulder tension, less rushing, and more complete exhales.

From the mouth versus nose discussion, the next step is mechanics. MacKenzie talks about optimal breathing and about thinking in breathing gears. That idea is useful because it treats breathing the same way you would treat pace or power. A lower gear fits sleep preparation, recovery work, and easy aerobic sessions. A higher gear fits intervals, heavy efforts, or moments where output clearly has to rise.

Problems start when high gear becomes your baseline. People can drift into overbreathing, meaning they move more air than the moment calls for, and that pattern often brings more tension, more air hunger, and less control. Efficient breathing keeps your response proportional to the actual demand.

WHOOP members can look for indirect signs that a lower-gear pattern is becoming easier to access. A consistent bedtime routine, steadier resting heart rate, and better Recovery trends can all support the sense that breathing is becoming less reactive. The value comes from patterns across weeks, not from a single good day.

If you want to hear MacKenzie go deeper on breathing gears and efficient mechanics, watch the full episode on YouTube.

What you should take away

• Efficient breathing matches the task instead of staying stuck in a stressed pattern.
• Lower-gear breathing is useful for recovery, sleep preparation, and easy aerobic work.
• Overbreathing can create extra tension and make effort feel harder than it needs to feel.

How can you build a breathing routine that lasts?

A breathing routine lasts when it is short, repeatable, and tied to moments that already exist in your day. The best practice is usually the one you can keep doing long enough to see a trend.

MacKenzie closes the episode with protocols, awareness, and the idea that breathing skill starts with noticing your current pattern. That makes habit design straightforward. A few minutes before bed can support a calmer transition into sleep. A short drill before training can help you settle into the right intensity. A brief reset after hard work can help you leave high gear behind instead of carrying it into the rest of the day.

The research base points in the same direction. The structured respiration study above used only five minutes a day for a month, which is a useful reminder that consistency beats occasional heroic effort. For WHOOP members, a routine becomes more concrete when you compare it with Sleep, HRV, respiratory rate, and Recovery rather than relying on memory alone. Episode 84 of the WHOOP Podcast is helpful background on why respiratory rate became part of Recovery.

If you already use the WHOOP Journal, logging a breathing session gives you a way to spot whether the habit lines up with steadier nights and better readiness. If the data stays flat, you can adjust duration, timing, or intensity and keep testing from there.

If you want to hear MacKenzie unpack practical breathing protocols and awareness, listen to the full episode on Spotify.

What you should take away

• A short daily breathing practice is easier to keep and easier to evaluate.
• Before bed, before training, and after intense work are useful places to anchor the habit.
• WHOOP metrics can show whether the routine lines up with better sleep and next-day readiness over time.

The bottom line

• Breathing is a trainable skill that can influence stress, sleep quality, and exercise control.
• Short, repeatable breathing practices can improve mood and reduce physiological arousal.
• Hypoxia raises breathing demand and should be used with clear purpose and recovery awareness.
• Nasal breathing can help regulate easy effort and support a calmer breathing pattern at rest.
• Respiratory rate is useful because it tends to be stable in healthy conditions, so deviations can stand out clearly.
• Efficient breathing is quiet, rhythmic, and matched to the actual demand of the moment.
• WHOOP data helps turn breathing practice into something you can evaluate across weeks instead of guessing from one session.

Frequently asked questions about things discussed in this episode

How does WHOOP measure respiratory rate?

WHOOP measures respiratory rate during sleep by analyzing repeating patterns in sensor data from the wrist and comparing the result with your normal range over time.

What does WHOOP do for tracking breathing changes over time?

WHOOP shows respiratory rate as a nightly trend, which is useful because healthy respiratory rate usually changes very little from night to night.

How can WHOOP help you see whether breathwork is helping recovery?

WHOOP helps you compare a breathing habit with Recovery, HRV, resting heart rate, Sleep, and respiratory rate trends so the routine can be judged over weeks instead of by feel alone.

What does WHOOP show if sleep breathing seems off?

WHOOP can surface indirect signs of a rougher night through changes in respiratory rate, Sleep, resting heart rate, and Recovery, which gives you more context for how the night affected readiness.

How does WHOOP help on training days when breathing feels harder than usual?

WHOOP gives you baseline context by showing whether recent Sleep, Recovery, Strain, and respiratory rate trends support what you are feeling in the moment.

What does WHOOP do for building a breathing habit?

WHOOP makes breathing practice easier to track by pairing logged behaviors, including entries in the WHOOP Journal, with measurable trends in sleep and recovery.

Breathing is one of the few inputs you can change in real time, and WHOOP helps show whether that change is actually carrying into better sleep, steadier respiratory rate, and more reliable readiness.