How to Read Your VO₂ Max Test Results: Score, Zones, and the Two Thresholds That Actually Matter

You just finished a VO₂ Max test. You were on the treadmill or bike, breathing into a mask, watching the intensity climb until you couldn't go any further. Now someone hands you a report with numbers, graphs, and zone charts. You find your VO₂ Max score, maybe Google whether it's good or bad, and move on with your life.

That's what most people do. And it means they're ignoring the most useful parts of the test.

Your VO₂ Max number is the headline, not the story. The story lives in two thresholds buried further down in your report that most people skip right past. Those thresholds tell you exactly how to train, where your aerobic engine breaks down, and why you feel the way you feel at different intensities.

Here at Mavericks, we walk every client through their full results after testing. This article is what we wish every person read before that conversation.

The three numbers in your report

Every proper metabolic test gives you at least three key data points. If yours only gave you one, you didn't get a real test.

VO₂ Max is your ceiling. It's the maximum amount of oxygen your body can use during all-out effort, measured in milliliters per kilogram per minute. A higher number means a bigger engine. That's the one everyone fixates on, and the one that shows up in the percentile charts. If you want to know where your number ranks, we break that down separately.

VT1 (Ventilatory Threshold 1) is your aerobic floor. It's the intensity where your breathing first shifts from easy and automatic to something you have to manage. Below VT1, you could talk in full sentences without thinking about it. At VT1, you start to notice your breathing. You can still hold a conversation, but it takes a little effort.

VT2 (Ventilatory Threshold 2) is your anaerobic ceiling. It's the intensity where your body starts producing lactate faster than it can clear it. Your breathing becomes labored and rhythmic. Conversation drops to short phrases. You know you're on borrowed time. This is the point where things start to unravel if you stay there too long.

Your report should show each of these at a specific heart rate, pace or power output, and oxygen consumption. Those are the numbers that drive your training. The VO₂ Max score tells you how big the house is. VT1 and VT2 tell you where the rooms are.

What VT1 means in plain English

VT1 is where you shift from comfortable to controlled.

Below VT1, your body is running almost entirely on aerobic metabolism. Fat is a primary fuel source, your breathing is relaxed, and you could sustain that effort for a very long time. This is the kind of effort where you zone out on a long walk or an easy jog and barely notice you're exercising.

At VT1, things change. Your body starts relying more on carbohydrates. Carbon dioxide production ticks up, and your breathing rate increases to blow it off. You're not suffering. You're not gasping. But you've crossed a line. The effort now requires attention.

Why this matters for training: VT1 is the upper boundary of true aerobic training. If you want to build your aerobic base and develop endurance that actually lasts, the bulk of your training should happen at or just below this threshold. We see clients all the time who think they're doing "easy cardio" but are sitting above VT1 for their entire session. They're working harder than they think and getting less aerobic benefit than they should.

When we talk about Zone 2 training and how it specifically improves your VO₂ Max, VT1 is the ceiling of that zone. Not a generic heart rate formula. Your actual, tested VT1. That's the difference between guessing and knowing.

What VT2 means in plain English

VT2 is where you start going into debt.

At VT2, lactate production outpaces clearance. Your muscles are acidifying. Your breathing becomes hard and fast, not because you're choosing to breathe that way, but because your body is desperately trying to buffer the rising acidity by blowing off CO₂. It's that intensity where you know you could hold on for maybe ten or fifteen minutes, but not thirty. Not an hour.

This is your redline. Training above VT2 has a place in any well-designed program. Intervals above VT2 improve your body's ability to tolerate and clear lactate, increase cardiac output, and push your VO₂ Max ceiling higher. But the key word is intervals. You go above VT2 intentionally, for a specific duration, with planned recovery. You don't live there.

Most of our clients are surprised by where their VT2 falls. People who consider themselves fit often find it lower than expected, which means they've been redlining more often than they realized. That's not toughness. That's inefficiency.

The gray zone: where most effort goes to waste

Here's the part that changes how people train after they see their results.

Between VT1 and VT2, there's a range we call the gray zone. It's too hard to build your aerobic base effectively and too easy to stimulate the high-intensity adaptations that push your ceiling up. It's the intensity where you break a good sweat and come home feeling like you did something. And in many cases, it's the least productive place you could spend your time.

We see this pattern constantly. A client tells us they run three or four times a week at a "moderate" pace. They're consistent. And their fitness has been flat for two years. When we test them, their "moderate" pace sits right in the middle of the gray zone. Every run. Same stimulus, same response, no adaptation.

The fix is counterintuitive. Train easier on your easy days and harder on your hard days. The majority of your volume should be below VT1, building aerobic capacity, improving mitochondrial density, and teaching your body to burn fat efficiently. A smaller portion should be above VT2, pushing the ceiling and building tolerance to high-intensity work. The gray zone gets used sparingly, usually for tempo work or race-specific preparation.

This is what coaches call "polarized training." It's not a fad. It's what the data from your test is telling you. VT1 and VT2 draw the lines. You train below the first one and above the second one. The middle is for specific purposes, not for default effort.

Your test zones vs. the ones on your watch

If you wear a fitness tracker, it probably shows you five heart rate zones. Zone 1 through Zone 5, usually calculated as a percentage of your estimated max heart rate. Those zones are generic. They're based on population averages and a formula that doesn't know anything about your body.

The zones on your VO₂ Max test report are different. They're based on your actual physiology, anchored to your measured VT1 and VT2. That matters more than most people realize.

Here's a common example. A client's watch says their Zone 2 ceiling is 138 bpm based on a max heart rate formula. Their actual VT1, measured in the lab, comes in at 126. That's a twelve-beat difference. Every time this person trains at 130 thinking they're in Zone 2, they're actually above their aerobic threshold, sitting in the gray zone, getting a worse aerobic stimulus than if they just slowed down.

We've also seen the opposite. Someone whose VT1 is higher than the formula predicts, meaning they've been training too easy and leaving adaptation on the table.

The point isn't that your watch is useless. It's that generic zones are estimates, and estimates have error margins. Once you have your tested thresholds, you can reprogram your watch with real numbers. Now the zones actually mean something. Your report from a full metabolic evaluation gives you everything you need to make that update.

The metric most clients skip: respiratory exchange ratio

Somewhere in your report, there's a number called RER, or respiratory exchange ratio. It's the ratio of carbon dioxide your body produces to the oxygen it consumes. Most clients glance at it and move on. That's a mistake.

RER tells you what fuel your body is burning at different intensities. An RER of 0.70 means you're burning almost entirely fat. An RER of 1.0 means you're burning almost entirely carbohydrates. Most people sit somewhere around 0.85 at rest and climb toward 1.0 and above as intensity increases.

What makes RER interesting is not the number at max effort. Everyone's RER goes above 1.0 when they're going all out. What's interesting is the RER at lower intensities, particularly around VT1.

We see two common patterns. Some clients show an RER of 0.90 or higher even during easy efforts, burning a disproportionate amount of carbohydrate relative to fat. These are often the people who bonk during long efforts, who feel shaky if they skip a meal before a workout, who rely on gels and snacks to get through endurance sessions.

Other clients maintain a lower RER well into moderate intensities, meaning their bodies are efficient at using fat as fuel even as the work gets harder. That's a trainable quality. Consistent aerobic work below VT1, the kind most people skip because it feels too easy, shifts this ratio over time. Your body gets better at accessing fat stores, sparing glycogen, and sustaining effort without constant fueling.

RER is often the data point that creates the biggest shift in how our clients think about training. It takes the abstract idea of "aerobic base" and makes it concrete. You can see it in the numbers. And you can see it change when you retest.

What to do with all of this

Your VO₂ Max score gives you a snapshot of your cardiorespiratory fitness. It's a number you can track, compare, and improve. But the score alone doesn't tell you how to train.

VT1 tells you where to cap your easy work. VT2 tells you where your hard work begins. The gap between them is the gray zone you should mostly avoid. RER tells you how efficiently your body is using fuel at different intensities. Together, these numbers give you a training plan that's built on your physiology, not on someone else's formula.

If you've already been tested and have your baseline numbers, the question becomes when to come back and retest. The thresholds move. That's the whole point. Training should shift them, and retesting confirms whether it did.

If you haven't been tested yet, this is what a full evaluation at Mavericks includes. Not just a number on a chart, but a complete picture of how your body works under stress and what to do with that information.

The score is the headline. The thresholds are the story. And now you know how to read both.