Everything we're working through, in one place. There are two kinds. A check takes one claim people keep repeating and puts it through the whole method — every source read twice, and two more readings that set out to break it. An explainer hands you the machinery underneath, so the next claim doesn't need checking by us before you can see it for what it is.
Four are done, two are up next. Three explainers are live — how to read a training study, the one on VO2max, and what your watch actually measures — along with the first deep-dive, on the super shoes. Below them: the check and the explainer we're working on right now. The rest of the queue lives in our planning, not on a shelf of empty cards — a new piece appears here the moment it's real.
What your watch actually measures
A sports watch senses about four things and works out the rest. Which numbers come from a sensor, which from a formula, and which from a guess about you — heart rate, distance, calories, VO2max, training load, max heart rate, HRV and readiness.
Read the explainerVO2max: what it tells you (and what it doesn't)
A user's guide to the most-cited number in endurance sport: what it means, the three routes to a value, why two runners with the same VO2max can finish minutes apart, and what the mortality-tail actually says.
Read the explainerHow to read a training study
Seven questions that tell you how far a finding travels: who was in it, how many, how long, compared with what, what was measured, how big the difference was — and whether it would have been published if it had found nothing. No statistics needed.
Read the explainer“Carbon-plate shoes make you 4% faster.”
The famous 4% is now 2.75%, most of it never reaches your finishing time, and the plate turns out not to be the part doing the work — the shoe as a whole is. Read twice, by two people, against every source we could get hold of.
Read the deep-dive“Zone 2 is the base every engine needs.”
The most-repeated training advice of the decade. We'll look at what the polarised-training research really compared, whether the magic is the zone or simply the volume, and what happens if you have eight hours a week instead of twenty.
Training zones, from scratch
What training zones actually are, why "zone 2" means something different in a three-, five- or seven-zone model, what each zone is for, and how to find yours without a lab.