When does LE LAB open in London?

Honestly: we don't know yet, and we won't announce a date before a venue and a team are signed. What is certain: if you're on the list, you'll hear it first, with the first slots and the founding rate.

When should I test before the London Marathon?

8 to 12 weeks before race day. Earlier, your fitness will still move a lot before the start. Later, you no longer have a full block left to train on your measured zones.

What does the test involve?

A progressive effort of 20 to 30 minutes on a treadmill, with a mask analysing your breath. We measure your oxygen uptake continuously and detect your two ventilatory thresholds. You get your VO2max, your thresholds, your running economy and your fuel profile in a written report.

Is it different from the VO2max on my watch?

Yes. Your watch estimates VO2max with an algorithm based on pace and heart rate. The lab measures it directly in the air you breathe out, and detects your thresholds, which a watch cannot see.

How much does it cost?

LE LAB assessments start at €169 in Paris. People on the waiting list get a founding rate on their first assessment when the London lab opens.

Can I get tested somewhere already?

Yes, at the LE LAB flagship in Paris, 11 rue du Vertbois (3rd arrondissement). Booking is online at lelab.run/reserver.

Coming to London?

VO2max test in London, before the marathon.

VO2max, ventilatory thresholds and running economy measured in one session, in a real exercise physiology lab. Your watch estimates. The lab measures.

Join the waiting list

Updated: September 2026

LE LAB wants to open in London, and the choice of our next cities is simple: we open where most runners are waiting. Every sign-up moves London up the list. Until then, our flagship lab is in Paris, where LE LAB has run more than 300 tests since January 2026, with the same protocol and the same report we would bring to London.

LABWritten by the LE LAB teamExercise physiologists and founders of LE LAB

Your testing window

Test 8 to 12 weeks before race day.

The TCS London Marathon is on 24–25 April 2027. Testing 8 to 12 weeks before is early enough to train a full block on your measured zones, and late enough for the numbers to still describe you on the start line.

Race date: official website

Why London

The biggest start line in the world, trained on estimated paces.

In 2027 the London Marathon runs over two days for the first time, to welcome a record field. Most of those runners will build their block on paces and heart-rate zones estimated by a watch or a formula, not measured.

A lab test replaces the estimate with a measurement: your real VO2max, your two thresholds, the heart rate and pace at which each one happens. Done 8 to 12 weeks before race day, it sets the zones for your whole specific block, and tells you whether your goal time matches your engine.

VO2max test at LE LAB: runner on a treadmill wearing a gas-analysis mask, tester at the measurement station

What you get

A report written by a physiologist, not a printout.

The effort itself lasts 20 to 30 minutes, on a treadmill, wearing a mask that analyses every breath. Your report is written within 48 hours: three levels of reading, your training zones in heart rate and pace, and the raw data for your coach.

What we measure

VO2max: mL/kg/min. Your aerobic ceiling.
VT1 and VT2: Your two thresholds, which set your zones.
Running economy: How much oxygen each kilometre costs you.
Fuel use: Fat vs carbohydrate at every intensity.
Marathon pace check: Where your goal pace sits against your thresholds.

Waiting list

London, your move.

The first sign-ups open the lab. Three benefits, reserved for the waiting list.

Priority

The first slots go to you, before bookings open to the public.

Founding rate

A launch offer reserved for the list, on your first assessment.

Your voice counts

Cities open in order of demand. Your sign-up moves London up.

Questions

What you need to know.

Other spring marathons

We open where demand is highest. Every sign-up counts for its city.