VO2 max, demystified
Bobby Ghadery is a trainer, sports nutritionist, and the owner of Integrative Performance in Arlington, Virginia. The Hybrid Letter spoke with Bobby about V02 max testing, including the definition of VO2 max, how a VO2 max test is conducted, what kind of data it produces, and how that data can be used to improve the performance of athletes in Hyrox and other hybrid fitness races.
This interview has been edited for length in clarity
The Hybrid Letter: What got you into opening up this gym and V02 max testing?
Bobby Ghadery: I started as a business major, but I had a quarter-life crisis. I switched to pursue integrative medicine and traditional Chinese medicine. I moved to California for that, but then I came back to the DC area and started training at Equinox. I eventually became a Master Instructor for the DMV region.
I got a lot of great continued education there—advanced program design, biomechanics, muscular physiology, cardiovascular physiology, and so on. I also earned a couple of nutrition certifications. Over time, I started branching out into diagnostic testing. For me, it’s about bringing everything together.
THL: What type of people get tested at your facility?
BG: We see a wide range. A lot of runners and cyclists come in, as well as weekend warriors, recreational athletes, and people who’ve been out of fitness for a while. We’ve tested amateur athletes all the way up to serious ones, like someone training for the Spartathlon, a 143-mile ultra-marathon. Because we’re in Arlington, we also see a lot of military personnel preparing for their physical tests.
THL: What is a VO2 max test?
BG: A VO2 max test measures the maximum volume of oxygen someone can take in, expressed in milliliters per minute per kilogram of body weight.
Most people think of it as a running metric, but it’s so much more than that. Fundamentally, your body’s ability to circulate and use oxygen is critical for everything you do. Fitness, at its core, is about oxygen transport—whether it’s to your cardiac tissue, your muscles, or even your toes.
It’s not just about heavy breathing during cardio. Oxygen is essential for breaking down and metabolizing energy, which powers everything else. VO2 max gives you a baseline to train smarter.
THL: How do you test VO2 max?
BG: We’ve developed our own approach over the years. First, we fit the client with a gas analyzer mask and a chest heart rate monitor.
The test starts with a five-minute warm-up at a casual pace—usually on a treadmill, though we adapt based on the client’s preference. Standard protocols typically increase speed and incline every few minutes until you max out, but we take a more linear approach.
We gradually increase speed by a predetermined amount each minute until the client reaches their peak. This process takes about 10–15 minutes after the warm-up. We avoid ramping up too quickly, so there’s time to collect good data and allow the client to oxygenate properly.
THL: Why don’t you use incline during the test?
BG: Incline can be limiting for a lot of people. If you’re sprinting at a high grade for an extended time, things like dorsiflexion or shin angles can become the limiting factor instead of cardiovascular capacity.
By removing incline, we get more consistent results. Our treadmill also allows for speeds beyond most commercial models, so we don’t need to rely on incline for testing higher-performing athletes.
THL: When is the best time for someone to take a V02 Max test?
BG: Ideally, at the beginning of a training cycle or right after you’ve peaked and had a few recovery days. We recommend not doing any intense activity for at least 24 hours before the test—no HIIT, no long runs, nothing that leaves you sore or depleted.
If you’re early in your cycle, it’s great for setting a baseline. If you’re in the final stages, I usually say stick to your plan. The data might throw you off mentally, whether it’s good or bad, and at that point, it’s better to focus on execution.
THL: What kind of information do people get from this test?
BG: A lot. They get their VO2 max, max heart rate, heart rate graph, ventilation (the volume of oxygen brought in per minute), tidal volume (lung capacity), and respiratory frequency (breaths per minute). We also measure fractional expired oxygen to show how much oxygen is actually being utilized.
We break heart rate zones into five categories, based on metabolic transitions and caloric expenditure. Clients also see their aerobic and anaerobic thresholds—key points where their body shifts how it uses energy.
The real value comes from interpreting the data. We look for inefficiencies, stress points, or irregular breathing patterns and help people build from there.
THL: How do you break down the guidance you provide athletes?
BG: It really depends on the person, but we typically start with pace work or distance training, where someone focuses on extended periods of effort to build their aerobic base. That’s often the foundation. From there, we look at sub-threshold or tempo work, which is about finding your peak sustainable power. That’s the zone where you’re using a lot of energy, and it’s metabolically demanding, but you can maintain it for a decent amount of time.
Then there’s speed work, which is designed to push you beyond your anaerobic threshold with intervals. It’s about creating that acute overload where your body has to recover and adapt. That adaptation happens at the cellular level—down to the mitochondria—and it’s what really drives improvement.
But whether someone needs more focus on aerobic base-building, tempo work, or speed training depends on their goals and current fitness level. It’s all tailored to the individual.
THL: How does lactate threshold fit into this?
BG: Lactate threshold is pretty much directly tied to your anaerobic threshold. It’s the point where your body can’t keep up with the energy demand or clear metabolic waste fast enough. If you go a little above that, you can sustain it for a short time. If you go way above it, you’ll either have to pull back, cramp, or stop entirely.
For endurance athletes, you don’t necessarily want to train right at that point unless it’s part of a specific strategy. But for sports with constant bursts of intensity—like basketball or soccer—it’s much more relevant. Just like anything, improving your lactate threshold is a marker of fitness, but how much you train at that level depends entirely on your goals.
THL: Why is this useful for Hyrox athletes?
BG: Pacing. That’s the biggest thing. A lot of people either start too fast and burn out, or they finish with too much left in the tank. VO2 testing helps us get specific about pacing and metabolic zones so you can optimize your performance.
For Hyrox, where every other part is a 1K run, we can design a plan that builds aerobic pace and uses sub-threshold work for those runs. We’ve tested a lot of Hyrox athletes and helped them dial in their pacing so they can perform consistently and efficiently throughout the event.
THL: What’s a common question you get from athletes?
BG: Zone 2 training. It’s probably the most popular topic. A lot of people hear about it on podcasts or read about it in books, and it’s great for recovery or injury prevention. But if you’re looking for adaptations, Zone 2 alone might not give enough stimulus. It’s like weightlifting—if you’re capable of squatting 100 pounds but only do bodyweight squats, you’ll stay mobile and burn calories, but you won’t get stronger.
What we do is help people figure out where they should be training and why. It’s about maximizing efficiency, especially for people with limited time to train.
You can follow Bobby on Instagram
Science Corner: Blood lactate testing
An alternative to V02 max testing that can also be useful for hybrid training is a blood lactate test. Anthony Peressini, who coaches many top Hyrox athletes, including his wife Lauren Weeks, offered a detailed explanation of blood lactate testing on YouTube.
Peressini discusses how a blood lactate test is conducted, what you can learn from the test, and how to apply it to hybrid training:
Watch the best: Hyrox Hong Kong
One of the best ways to improve your race strategy is to watch how the very best attack the course. Many of the best racers just completed the second Hyrox Major of the year in Hong Kong. You can watch a replay of the action here:
Hybrid Athlete of the Week: Mariesa McCulloch
Name: Mariesa McCulloch
Age: 36
Hometown: Morrisville, NC
Why did you start hybrid racing? I started hybrid training in 2019 after signing up for my first Hyrox, which took place in 2020 in Chicago. I decided to go the hybrid route because I was tired of running obstacle course races and needed a change. I also fell in love with the hybrid training style—compromised running was fun and challenging for me!
Favorite race to date? My favorite hybrid race has to be that first Hyrox in 2020. I asked my fitness friends if they wanted to do it with me, but they thought I was crazy and weren’t interested. So, I signed up for the Pro wave—why not?—and went by myself. My sister and niece came along for support, but otherwise, I was on my own.
I had no idea what I was getting into. I used a SkiErg for the first time ever just two days before the race. I didn’t really know how to train for it back then, but I was pumped and ready. I finished in about an hour and 30 minutes, and it was the hardest thing I’d ever done. I was hooked on hybrid racing from that moment.
That race stands out because it pushed me way out of my comfort zone. Walking into a room full of incredibly fit people doing something I had never tried before was intimidating, but I did it! My sister even snapped a picture of me running as Hunter McIntyre flew past me—that was pretty cool too.
Do you have a race goal? Right now, I’m hunting Terra Jackson down with my DEKA Strong time. The thing is, as I get faster, so does she, so it’s an ongoing chase. I recently PR’d my Strong time with 12:45, and now my next target is 12:30.
For Hyrox, my goal is to get my Pro time down to an hour and 15 minutes by the Houston race next year.
Favorite station? For DEKA, it’s the bike. My coach has me on the bike so much during training that it’s become automatic for me. It’s not easy, but it’s also not the worst thing I’ve ever done.
For Hyrox, I’d have to say burpee broad jumps. I know it sounds crazy, but I love burpees. No one ever believes me when I say that, but it’s true!
Least favorite station? For DEKA, it’s the farmers carry. It gets my heart rate sky-high, maybe because I’m anticipating the bike station that comes next. Those 40-pound dumbbells don’t seem heavy at first, but by lap three, they feel unbearable. It never seems to get easier.
For Hyrox, it’s the rower. By the time I get to it, I’m usually fighting for my life. The rower just takes so much out of me—I’d honestly rather be doing wall balls.
Something you wish you knew when you started racing? You can’t compare yourself to others. That’s a surefire way to feel bad about yourself. You have to trust the process because things don’t happen overnight.
One of my former coaches used to tell me, “There will always be someone fitter than you. You just have to do the best you can at the fitness level you’re at.” That still resonates deeply with me. My current coach reminds me to have realistic expectations, which I think about a lot before races. You can’t be fitter than you are in that moment. Learning to meet myself where I’m at has been a game-changer for me and has helped me so much in competitions.