Blood Lactate, VO₂ Max, or Both? How to Pick the Right Test

We run three testing options at the clinic: a blood lactate threshold test, a VO₂ max test, and a combined session that does both in one visit. Clients ask us most days which one they actually need. Here's the honest breakdown.
Before you book anything, it helps to separate two different questions your training raises. One is: *what intensity should I actually be training at?* The other is: *how big is my aerobic engine, and how efficiently am I using it?* The lactate test answers the first. The VO₂ max test answers the second. The combined session answers both and gives you a third number neither test can produce alone.

The Blood Lactate Test: For Getting Your Zones Right

This is a graded step test on the treadmill, with a small blood sample taken at the end of each stage to track how lactate builds as the effort increases. From that curve we pull your two thresholds — LT1 and LT2 — and translate them into heart rate, pace, and power zones that are yours, not a generic formula off your watch.

If you've ever wondered whether your "easy" runs are actually easy, or you've paced a race off a guessed heart rate zone and blown up in the second half, this is the test that fixes it. It's also the one we recommend most often, because zones are what you train and race by every single week, getting them right changes almost every session you do afterwards.

This is your test if: you train by zones already (or want to) and you're tired of estimating them.

The VO₂ Max Test: For Your Ceiling and Your Efficiency

This test uses gas analysis via our VO₂ Master system to measure the maximum rate at which your body can use oxygen your aerobic ceiling alongside your running or cycling economy, which is how much oxygen you burn to hold a given pace or power.

It doesn't tell you where your thresholds sit. What it tells you is how much engine you're working with, and how efficiently you're using it. Two athletes can share a threshold pace and still have very different ceilings above it. Two athletes can share a VO₂ max and differ hugely in economy, which is often the real reason one of them is faster on the day.

This is your test if: you want a season benchmark for your aerobic capacity, or you're chasing marginal gains in efficiency rather than raw fitness.

The Combined Session: The Full Physiological Picture

Running both tests in one session doesn't just save you a second visit; it produces a number neither test can give you on its own: your **fractional utilisation**, the percentage of your VO₂ max you can actually sustain at threshold.
Fractional utilisation is one of the strongest single predictors of endurance performance we have. It's the reason two athletes with an identical VO₂ max can have completely different race outcomes. One can hold 88% of their ceiling for an hour, the other can only hold 75%. You can't see that number without measuring thresholds and ceiling together, in the same session, under the same conditions.
The combined session gives you your full profile in one sitting: ceiling, thresholds, economy, and fractional utilisation. It's the option most of our seriously competitive clients choose, and it's also the best starting point if you want a complete baseline to track across a season rather than a single answer to a single question.
**This is your test if:** you're training toward a specific goal and want the complete picture, not one slice of it.

Quick Comparison

Question you're askingBest test"What pace/power/heart rate should I train at?"Blood lactate test"How big is my aerobic engine, and how efficient am I?"VO₂ max test"What's my full physiological profile, including what I can actually sustain?"Combined session

Running, Cycling, or Both?

All three tests are available for running (treadmill) or cycling (bike). If you split your training across both, triathletes and Hyrox athletes especially your thresholds and ceiling won't transfer directly between disciplines, so test in whichever you're training for, or both if your season demands it.