If you’ve ever done a VO2max test, you know this number. Higher is better. Simple.
But here’s the twist: a high VO2max doesn’t automatically mean good endurance.
Why? Because there’s another parameter that most athletes have never even heard of: VLamax.
What is VO2max?
VO2max is the maximum amount of oxygen your body can use during maximal effort. It’s measured in ml/kg/min.
Metaphor: VO2max is the size of your engine.
Bigger engine = more horsepower = higher maximum output.
Examples:
- Recreational athlete: 45-50 ml/kg/min
- Strong amateur: 60-65 ml/kg/min
- Pro cyclist: 75-85 ml/kg/min
What is VLamax?
VLamax is the rate of lactate accumulation in your blood during maximal effort. It’s measured in mmol/L/s.
Metaphor: VLamax is how much fuel your engine burns while idling.
Lower VLamax = less lactate buildup = better endurance at high intensities.
Examples:
- Ultra-endurance athlete (Ironman): 0.2-0.3 mmol/L/s
- Road cyclist (classics): 0.4-0.5 mmol/L/s
- Sprinter: 0.6-0.8+ mmol/L/s
Why VLamax Matters (Maybe Even More Than VO2max)
Imagine two athletes:
Athlete A:
- VO2max: 70 ml/kg/min
- VLamax: 0.6 mmol/L/s
Athlete B:
- VO2max: 65 ml/kg/min
- VLamax: 0.3 mmol/L/s
Who’s going to perform better at an Ironman?
Athlete B. And it won’t even be close.
Why? Because an Ironman isn’t a maximal effort — it’s a sub-maximal effort sustained over a long time. VLamax determines how well you can maintain high intensity without your lactate blowing up.
Different Disciplines = Different Profiles
Here’s the key: your ideal profile depends on your discipline.
Sprinters (track, criterium)
- High VO2max — yes
- High VLamax — yes
- You need explosiveness, short maximal efforts
Road Cyclists (classics, stage races)
- High VO2max — yes
- Mid-range VLamax — balanced
- You need the ability for short maximal efforts (attacks, climbs) + endurance
Ironman / Ultra-endurance
- Mid-to-high VO2max — balanced
- Low VLamax — absolutely critical
- You need the ability to sustain high intensity for a long time without lactate accumulation
What Does This Mean for Training?
This is where it gets interesting: VO2max and VLamax are trained differently — and sometimes in opposite ways.
How to raise VO2max:
- VO2max intervals (3-8 min @ 95-105% FTP)
- Short maximal efforts
- High intensity, long recovery
How to lower VLamax:
- Long, steady aerobic rides
- Threshold work (steady state)
- Avoiding sprints and maximal efforts
- Increasing volume
The problem: If you’re training for an Ironman and you’re doing “race-pace” sprint intervals, you can actually raise your VLamax — which is the exact opposite of what you need.
My Approach: INSCYD Testing
This is exactly why I use INSCYD: it gives me both parameters.
A classic FTP test doesn’t tell you your VLamax. A classic VO2max test doesn’t tell you your VLamax. A lactate test gives you thresholds, but not the full model.
INSCYD tells me:
- Your VO2max
- Your VLamax
- What kind of profile you have
- What you need to train for your specific goal
Real-World Example
I recently tested an athlete preparing for an Ironman. His results:
- VO2max: 68 ml/kg/min (excellent)
- VLamax: 0.55 mmol/L/s (too high for IM)
The problem: He’d been doing too many “race-pace” intervals (threshold work with high-intensity bursts), which was pushing his VLamax up.
The fix: 8 weeks of:
- More volume (Z2 rides)
- Sweet spot instead of race-pace
- No sprints
- More long, steady efforts
Result after 8 weeks:
- VO2max: 67 ml/kg/min (minimal change)
- VLamax: 0.38 mmol/L/s (dropped by 30%!)
On race day: a 22-minute PB. Same FTP, different metabolic profile.
What Does This Mean for You?
If you’re training for ultra-endurance (Ironman, ultra-cycling, gran fondo):
VLamax is probably more important than VO2max.
If you’re training for short, intense efforts (criterium, XC MTB, short-course triathlon):
You need a high VO2max and an appropriately high VLamax.
If you’re training by guesswork without testing:
You might be training the completely wrong system for your goal. Find out with INSCYD testing.
Bottom Line
VO2max matters. But it’s not the only parameter that determines performance.
VLamax is the quiet parameter that most athletes ignore — but it’s critical for endurance.
If you want to truly optimize your training, you need to know both. And once you know where you stand, the next step is the right coaching plan to get you to your goal.
Want to find out your VLamax? INSCYD testing gives you a complete metabolic profile.