I didn’t get into breath training because it was trendy or scientific or sounded cool on a podcast.
I got into it because I was tired of feeling like my lungs were the weakest part of my running.
You know that feeling—legs are fine, fitness is there, but your breathing goes sideways and suddenly everything feels harder than it should. That panicky edge. The gasping. The why does this feel like mile 20 when it’s mile 6 moment.
For a long time, I thought that was just “how running is.” Turns out… not exactly.
What I learned—slowly, awkwardly, with a lot of trial and error—is that most runners don’t have an oxygen problem. We have a breathing control problem.
And more specifically, a CO₂ tolerance problem.
Once I started training my breath the same way I train my legs—progressively, patiently, without ego—everything changed.
My easy runs got easier. My hard runs felt calmer. Recovery between reps improved. Even race nerves stopped hijacking my breathing.
This isn’t mystical. It’s not biohacker nonsense. It’s a simple skill that most of us were never taught—and once you get it, it sticks.
What follows is exactly how I use CO₂ tolerance training in my own running and with athletes I coach.
No gadgets. No masks. Just practical stuff that actually carries over when the run gets uncomfortable.
If your fitness feels better than your breathing… this is for you.
1. Nasal Breathing During Easy Runs
This one’s simple but brutally effective: close your mouth and breathe only through your nose during your slow runs. Sounds easy—until you try it.
But it works because nose breathing forces you to slow down, breathe deeper, and retain more CO₂ per breath. Over time, this builds your tolerance and aerobic engine.
- How I started: I could barely jog for five minutes without panicking. Had to slow to a shuffle. But week by week, it got easier. Now I can cruise through a 5K with my mouth shut on easy days—and feel smooth doing it.
- Pro tip: That air hunger you feel? It’s not a lack of oxygen—it’s your body screaming because it’s not used to holding onto CO₂. Stay calm. Relax your shoulders. Breathe low into your belly. You are getting enough air.
- Why it works: Studies show that runners who train with nasal breathing adapt to higher CO₂ levels without losing oxygen efficiency. Their breathing gets smoother, heart rate drops, and endurance improves.
- Bali bonus: In the heat and humidity, mouth breathing dries you out fast. Nasal breathing saved me during long runs here—it helped me stay hydrated and kept my breathing calmer and more rhythmic. Felt like meditative movement.
- Use it when: You’re warming up, cooling down, or doing a recovery run. If you’re feeling bold, try it on a long run. Just know it’s okay to switch to mouth breathing during intense efforts—what matters is building the base.
2. Breath-Hold Intervals (During or After Runs)
This is where things get spicy. Once you’re comfy nose-breathing, start sprinkling in short breath holds to really nudge that CO₂ threshold.
Think of it like mini altitude training. Hold your breath just long enough to feel a medium urge to breathe—not long enough to panic.
Try this mid-run (step-holds):
- Exhale through your nose, pinch it shut, and jog 5 steps without breathing.
- Then release and breathe normally for 10–15 breaths.
- Repeat 4–6 times during your run, spacing them out.
As you improve, bump it to 8 steps. Then 10. But don’t go hero-mode. Stop while you still feel in control—like “I could have gone a bit more” but didn’t.
Try this during rest intervals:
- Doing hill sprints or 400m reps?
- During your recovery walk, take 2–3 normal breaths, exhale, and hold for 5 seconds.
Helps reset your breathing quicker. It’s like a reboot button. I’ve used this to steady my breath before the next rep without gasping like a fish.
Try this post-run (static holds):
- After your cooldown walk, take a breath in, out, pinch your nose, and hold.
- Hold till you feel a medium urge to breathe—maybe 10 seconds, maybe more.
- Breathe normally for 30 seconds. Repeat 3–5 times.
These are great for calming your body and extending your breath control when you’re not running.
- Safety note: Never do long holds while moving fast or in water. Don’t hyperventilate beforehand either—this isn’t about ego, it’s about training CO₂ tolerance, not blacking out.
- My results: I went from 5-step jogs to 15-step holds over a few months. Some days, I play “how far can I go with no air?”—sometimes I hit 30 steps. But I always stop before it gets sketchy. Breath holds are about control, not chaos.
- What changes: That tight, panicky feeling fades. You’ll find you can run faster before your breath gets ragged. Your redline starts moving. Recovery between intervals gets quicker.
I noticed I could hold tempo pace longer without getting winded—and that’s worth the short-term discomfort.
3. Box Breathing: Calm the Mind, Train the Breath
Not all breathwork needs to be done while running. Some of the best training happens flat on your back.
Box breathing is a calming, no-pressure way to raise CO₂ tolerance and chill your nervous system.
I use it before bed and sometimes pre-race to reset my brain.
Here’s how to do it:
- Sit or lie down. Hand on belly.
- Inhale through your nose for 4 seconds.
- Hold (lungs full) for 4 seconds.
- Exhale through your nose for 4 seconds.
- Hold (lungs empty) for 4 seconds.
That’s one “box.” Do this for 2–4 minutes.
- As you improve: Bump each phase to 5 or 6 seconds—just enough to challenge you. The exhale hold is where the CO₂ really builds up, so extending that is gold for tolerance training.
- Why it works: This method activates your parasympathetic system—the part that calms you down. It’s like a mini reset. And guess what? It also strengthens your diaphragm and breathing muscles. Win-win.
- When I use it: At night, after stressful days, or before a tough workout. It’s helped me sleep better, stay calm before races, and even curb anxious thoughts mid-run.
Other Breathwork Drills That Pack a Punch
So, box breathing is feeling easy? That’s your cue to level up.
Here are a few solid variations I’ve used personally and with my runners:
- Extended Exhales: Inhale for 4 seconds, exhale for 8. No holds. Just slow, deep breaths. Why? Long exhales build up CO₂ by naturally slowing your breath rate. It’s like doing slow reps at the gym—low intensity, high reward.
- 1:1:2:1 Breathing: Inhale 3, hold 3, exhale 6, hold 3. This one really teaches your body to stay calm under pressure, especially with that exhale hold.
- Alternate-Nostril or Buteyko Breathing: These are from yoga and CO₂ tolerance circles. The core idea? Control your breathing enough to feel a bit of air hunger—just enough to push your limits, not enough to panic.
I treat these like mini breathing workouts. On rest days, I’ll set a timer for 10 minutes: 5 minutes of box breathing, 5 minutes of long exhales, and maybe a few breath holds until I feel that comfortable air hunger.
And hey, if you’re a numbers nerd like me, track your progress. How long can you exhale without gasping? What’s your longest breath hold? Watching those stats climb feels just as satisfying as shaving time off your mile.
4. Diaphragmatic Breathing & Relaxation: The Quiet Hero
Not every session is about pushing CO₂. Some days, it’s about cleaning up your breathing habits—especially when most runners (yep, me included back in the day) breathe shallow and fast even at rest.
That’s where belly breathing comes in.
- Drill: Lie down with a small book on your stomach. Breathe in through your nose and focus on lifting the book with your belly—chest stays still. Exhale and let it drop. Do this for 2–3 minutes, slowly. The book is your feedback device. If it’s not moving, your diaphragm’s asleep at the wheel.
- Pair this with some mental cues: Inhale and think “calm.” Exhale and think “relax.” Simple, but it works. Over time, this will slow your resting breathing rate—ideally to 6–10 breaths per minute. That slight CO₂ increase improves your recovery and heart rate variability (HRV), which is a pretty good sign your nervous system is chill and balanced.
- Why it helps your running: When your default breathing is calm and deep, you’re less likely to panic-breathe during hard efforts. After doing this for a few months, I noticed that even on tempo runs, my body defaulted to belly breathing. No gasping. No panic. Just steady airflow, even when things got tough.
- Bonus win: This stuff is gold for managing race-day anxiety. A lot of runners I coach used to hyperventilate before the gun went off. Now, with a few minutes of pre-race breathing, they’re cool as a cucumber. That calm mindset carries through the race—and keeps mistakes and wasted energy to a minimum.
5. How to Fit Breathwork into a Busy Runner’s Life
You don’t need an hour a day to get the benefits. This is about weaving breathwork into your existing routine.
Here’s how I do it—and how I coach others to do it too:
- Warm-ups: During your dynamic stretches or first mile, breathe only through your nose. This keeps your start controlled and primes your CO₂ system.
- Easy runs: One or two chill runs per week? Go full nasal. Use the talk test. If you can’t finish a sentence, slow down.
- Post-workout: After intervals or tempos, I’ll walk for five minutes and sneak in some box breathing or gentle breath holds. It helps my body switch gears and absorb the workout.
- Bedtime or wake-up: I like five minutes of slow belly breathing before bed—it quiets the mind. You can also use it to set the tone in the morning. It’s like brushing your teeth but for your nervous system.
- Long runs: Toss in mini drills—every 10 minutes, hold your breath for five seconds or do a short nose-only segment. Don’t overdo it, especially before race day, but it’s a great mental reset mid-run.
- Race day (use wisely): Some of my marathon runners breathe through their nose for the first few miles to avoid going out hot. When things get tough later on, they switch to rhythmic breathing (like 3:2) and mentally remind themselves: “Slow your exhale. Stay calm.”
Avoiding the Breathwork Traps: Don’t Make My Mistakes
Pitfall 1: Going Too Hard, Too Fast
When I first got into CO₂ training, I went all in—trying to break breath-hold PRs every session.
Bad idea. I ended up lightheaded, frustrated, and dreading my practice.
Here’s the deal: This is not a no-pain-no-gain zone. It’s a consistency game. Start gentle. Build slowly. If you’re dizzy, anxious, or getting headaches—back off.
Pushing too hard can actually mess with your oxygen delivery by narrowing the gap between O₂ in your lungs and your blood. That means you’re doing the opposite of what you want.
Pitfall 2: Ignoring the Basics
Don’t expect breath training to save you from poor pacing or slouched posture. I always tell new runners: “You can’t breathe well if you’re red-lining in the first mile.”
Start at a pace where you can talk. Keep your posture tall, shoulders relaxed, chest open. That’s when breathwork can actually do its job.
Pitfall 3: Nose vs Mouth Myths
You don’t have to breathe through your nose all the time. It’s a tool, not a law. Nose breathing is best for easy runs and warm-ups.
But during hard sessions or races? Mouth breathing is totally fine.
Just make it steady and deep—avoid rapid, shallow gasps. I’ve had races where I started hyperventilating and it wrecked my rhythm. Lesson learned.
Elite runners? They use a mix—nose and mouth—keeping it smooth and calm.
Mistake: Ignoring Your Body’s Signals
Breath training’s supposed to be tough—but not reckless. If your diaphragm starts twitching or your throat gives you that tight “thump” mid-hold, that’s your body saying, “Time to breathe.” That’s the first urge. Respect it. Don’t white-knuckle your way through just to look tough.
I learned this the hard way early on—I pushed a long hold while sitting on the floor, blacked out for a second, and came out of it woozy. Not heroic. Just dumb.
If you ever feel dizzy or lightheaded, that’s your cue to stop and reset. Next time, shorten the hold. No gains come from gasping on the floor.
And let’s be real—this stuff’s not for everyone. If you’re pregnant or have uncontrolled high blood pressure, asthma, or other medical conditions, talk to your doc before messing around with CO₂ training.
Oh, and this should go without saying, but never do breath holds while driving or in water. Zero exceptions.
Mistake: Not Tracking Progress
You already track your pace and miles—so why not your breathing gains?
Seeing your BOLT score move from 15 to 25 seconds can be just as satisfying as shaving time off your 5K. I always tell runners to jot breathing notes in their logs.
Something like:
“Ran 5K easy, did 4×8-step holds—way smoother than last week’s 4×6.”
It’s a reminder that you’re moving forward, even if the gains feel subtle.
Progress tracking helps dial in the right training dose too. If your performance tanks or fatigue creeps in, maybe you ramped the breathing work too fast. It’s all connected.
Respect the Process, Reap the Gains
Breath training is more art than science. It’s about tuning into your body, not beating it into submission.
When it works, it just clicks—your breathing becomes part of the run, not an extra chore. That’s where the magic lives.
Embrace the Discomfort: How Breath Training Pays Off
There’s a phrase I love: “Get comfortable being uncomfortable.” It’s a mindset, and it’s the heart of breath training.
That moment where your brain’s screaming, “Breathe, now!”—that’s your window to grow.
Lean into it. Not recklessly, but with control. That’s where you build mental toughness that carries over to the hardest parts of your runs.
Final Word: Why This Matters
Getting better at breathing isn’t about chasing perfect. It’s about making running feel smoother, more fun, and less like a battle for every inhale.
You might not turn into Kipchoge, but you’ll notice that you’re running farther, faster, or with more calm—and that makes all the difference.
This shift in how I breathe literally kept me in the game. It’s one of the reasons I didn’t give up on running when it got hard.