What They Mean — and How to Improve Them
If you’ve ever looked at a fitness watch, a metabolic test, or a performance report and thought:
- “What is VO₂ max?”
- “What does aerobic threshold even mean?”
- “Is my anaerobic threshold good or bad?”
You’re not alone.
These three markers — VO₂ max, aerobic threshold, and anaerobic threshold — tell us a lot about your cardiovascular fitness. But more importantly, they tell us how to train smarter.
When you have your data, you don’t need to guess. You measure, interpret, and then train with purpose.
Let’s break it down.
What Is VO₂ Max?
VO₂ max is your body’s maximum ability to use oxygen during intense exercise.
In simple terms:
👉 It’s the ceiling of your aerobic engine.
The higher your VO₂ max, the more oxygen your body can deliver to working muscles — which generally means:
- Better endurance
- Higher work capacity
- Faster recovery between efforts
- Lower long-term cardiovascular disease risk
What VO₂ Max Indicates
VO₂ max reflects:
- Heart strength (stroke volume)
- Lung efficiency
- Blood oxygen transport
- Mitochondrial density in muscle
It’s a global measure of your aerobic potential.
But here’s the key:
It’s your potential — not your usable fitness.
That’s where your thresholds come in.
What Is Aerobic Threshold (AeT)?
Your aerobic threshold is the intensity at which your body begins to shift from primarily burning fat to relying more heavily on carbohydrates.
Below your AeT:
- Fat is the dominant fuel source
- Lactate production is minimal
- Effort feels sustainable
- You can hold a conversation
This is your Zone 2 range.
Why It Matters
A higher AeT means:
- You can go faster while still burning fat
- You build less fatigue at moderate efforts
- You recover better between sessions
- You create a stronger endurance base
For most people stuck in a plateau, this is the missing piece.
They train too hard, too often, and never build the aerobic base that supports long-term progress.
What Is Anaerobic Threshold (AT)?
Your anaerobic threshold — sometimes called lactate threshold — is the point where lactate accumulates faster than your body can clear it.
Above this heart rate:
- Fatigue increases rapidly
- Breathing becomes labored
- Speech is broken
- Effort is unsustainable beyond minutes
This is the red line.
Why Your AT Matters
The higher your AT:
- The longer you can sustain high output
- The faster you can run, row, bike, or ski before fatiguing
- The better your performance in competitive settings
In endurance sports, raising your AT often matters more than raising VO₂ max.
How to Read These Metrics
If you’ve had lab testing, you’ll usually see:
- VO₂ max (ml/kg/min)
- Heart rate at aerobic threshold
- Heart rate at anaerobic threshold
- Pace or power at your AeT and your AT
If you’re using a wearable device, estimates may be less precise but still useful for trend tracking.
What’s “Good”?
VO₂ max norms vary by age and sex, but here’s the reality:
Instead of obsessing over comparison, ask:
- Is mine improving?
- Is my AT pace increasing?
- Can I hold faster speeds at lower heart rates?
Improvement over time is what matters.
How to Improve VO₂ Max
To improve VO₂ max, you need exposure to high oxygen demand.
Methods:
- 3–5 minute high-intensity intervals
- Assault bike repeats
- Row intervals
- Hill repeats
- 90–95% max heart rate efforts
These sessions are uncomfortable — but short.
2x per week is plenty.
How to Improve Aerobic Threshold
This is where most people need work.
The Prescription:
- 2–4 Zone 2 sessions per week
- 30–60 minutes
- Conversational pace
- Heart rate just below AeT
This builds:
- Mitochondrial density
- Capillary networks
- Fat oxidation capacity
- Recovery efficiency
It feels easy. It works profoundly.
How to Improve Anaerobic Threshold
Raise your red line with:
- Tempo intervals (10–20 minutes slightly below AT)
- Sustained threshold pieces (e.g., 20-minute hard row)
- Broken intervals near threshold pace
These teach your body to:
- Buffer lactate
- Clear fatigue
- Sustain higher outputs
The Big Picture
Here’s the mistake people make:
They chase intensity.
But long-term performance — and long-term health — comes from building the full engine:
- Aerobic base
- Threshold capacity
- VO₂ max ceiling
And as we age?
Recovery, sleep, nutrition, hydration — they matter more, not less. You can’t out-train poor recovery anymore.
The body adapts.
The question is: are you giving it the right stimulus?
What This Means for You
If you’re stuck:
- Train easier more often.
- Train hard less often — but intentionally.
- Track heart rate.
- Build your base.
- Retest every 8–12 weeks.
Because fitness isn’t about being exhausted.
It’s about being capable.