Maximal oxygen uptake is a ceiling almost nobody reaches

The famous laboratory number sets an outer limit on endurance performance and says very little about who wins a race.

The test has enormous cultural weight. An athlete on a treadmill with a mask, the speed rising, the technician watching for the plateau, and at the end a figure that gets quoted for the rest of a career. It measures something real: the maximum rate at which the body can take up and use oxygen. It is also close to useless for separating two trained endurance athletes.

Here is why. Nobody races at that intensity. It can be held for a handful of minutes at most, which means it is only directly relevant to events lasting a few minutes, and even there the winner is not the athlete with the highest value. What decides a longer race is the fraction of that maximum an athlete can hold for the duration, and how much energy the running costs at a given speed. Two runners with identical laboratory numbers can differ by minutes over a half marathon because one holds eighty-five per cent of his ceiling and the other holds seventy-five, or because one simply uses less oxygen at the same pace.

That second quality, running economy, is the one I would test if I could only test one thing. It responds to training, to years of accumulated volume, to strength work, to technique, and to footwear, and it varies enormously between athletes who look similar on paper. It is also harder to measure well, which is presumably why the ceiling number kept the headlines.

The ceiling does matter at the entry gate. An athlete whose maximum is modest cannot become an elite distance runner by improving the fraction he can sustain, because the arithmetic runs out. So it functions as a screening device, useful for telling a talented junior whether the event is plausible, and largely irrelevant afterwards.

What annoys me is the way the figure circulates as a boast. It gets published, compared, and treated as a ranking of athletic quality, when a great many people with impressive numbers are mediocre racers and a fair number of very good racers test unremarkably.

It is the size of the engine. It tells you nothing about the gearbox, and races are won in the gearbox.