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Until recently, I didn’t give much thought to VO2 max the buzzy fitness metric that measures how efficiently your body uses oxygen during exercise. But after one breathless attempt to do cardio without mouth-breathing, I quickly realized mine needed work.
Let me back up.
VO2 Max: The Fitness Metric Everyone's Talking About
VO2 max, once the domain of elite athletes, has now become the gold standard among health optimization enthusiasts, runners, and even average gym-goers. A higher VO2 max is linked to better cardiovascular health, greater endurance, and even a longer lifespan.
You don’t need to run marathons to benefit from it. Studies show that even modest improvements in VO2 max can help reduce your risk of chronic diseases like heart disease, cancer, and diabetes.
As someone who loves yoga and pilates but loathes cardio, I figured a class focused on VO2 max could be the thing that finally changes my relationship with aerobic exercise.
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| The class involved switching between an assault bike and ski machine. Kim Schewitz |
I Signed Up for a Cardio Class That Promised to Boost VO2 Max
I tried a class called VO2:MAXED at GymBox in London a high-intensity cardio and breathwork session designed to increase aerobic capacity over a 16-week program.
Each class includes timed intervals on machines like the rower, assault bike, treadmill, or ski machine, with short breaks between sets. What makes this class different is its focus on breath control, specifically nasal breathing, to help improve oxygen efficiency and overall endurance.
Our coach, Firas Iskandarani, instructed us to breathe only through our noses (called “gear one”) for as long as we could, and to mentally note the moment we had to switch to mouth breathing (“gear two”).
If you can stay in “gear one” longer over time, it likely means your VO2 max is improving.
Sounds simple, right? Not exactly.
I Couldn’t Even Breathe Through My Nose for a Full Minute
We were told that fit individuals should be able to nasal-breathe for 90 seconds or more while working out. I tapped out in under a minute.
Halfway through class, we were given nasal strips to help widen our airways. While some athletes swear by them (tennis star Carlos Alcaraz wears them during matches), the science is mixed. One 2020 meta-analysis found nasal strips didn’t significantly improve VO2 max but they might make breathing feel easier.
Did the strip help me? A little. Until it slid off mid-workout thanks to sweat.
Nasal Breathing and "Zone 2" Training
Nasal breathing isn’t just a gimmick. It encourages you to stay in Zone 2 a sweet spot where your heart rate is 60–70% of its max. In this zone, your body can efficiently use oxygen for energy, which is key to building aerobic endurance.
Once you push into Zone 3 or higher, your body relies more on anaerobic systems, and your breathing becomes shallow and quick. That’s when the real huffing and puffing begins.
Staying in Zone 2 and breathing through your nose is harder than it sounds, especially if you’re new to cardio like me.
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| Kim Schewitz during the VO2 max-boosting class that lasted 50 minutes. Kim Schewitz |
The Mental Math Was Harder Than the Workout
Between watching the clock, counting my breathing "gear," and trying not to fall off the ski machine, I found myself overwhelmed. I accidentally switched to mouth-breathing several times without realizing it.
Still, I wasn’t gasping for air or red in the face like I am after a 35-minute jog. Instead, my arms were sore from the machines, but my body felt oddly energized afterward.
So… Was It Worth It?
For me, the class was a little too technical. But it changed how I think about cardio. Working out in a structured, supportive environment surrounded by people with similar goals was far more motivating than running alone and getting bored after 10 minutes.
And while I might not return to VO2:MAXED, I’ve discovered that taking a class with purpose (rather than zoning out on a treadmill) is the secret to making cardio a habit.
As someone who's only 28 and already struggling to keep up in a cardio class, the experience was a wake-up call. I don’t need to become a triathlete, but I do want to build a stronger, healthier heart that will carry me through the decades.
Cardio doesn’t have to be punishment. It can be playful, purposeful and even fun if you find the right fit.
So… anyone up for Zumba?
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