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Guides to measuring fitness.

Plain-English guides to VO₂max, ventilatory thresholds and metabolic testing, with sources for every claim. Written by the team building VenTracer.

Lab tests, field tests and watches: what each one measures, and what the number means.

The two breathing breakpoints that set your training zones, and how they are found.

What validation studies found when watch estimates were checked against lab tests.

A vendor-neutral checklist for labs and clinics comparing carts and portable systems.

What the large mortality studies found, and why clinics track fitness over time.

Also see The science for how VenTracer measures, and the FAQ.

Run a lab or clinic?

Help validate the first VenTracer units against your own reference equipment.