Lactate testing has turned into a ritual

A finger prick and a number give a squad the feeling of precision while the thing being measured drifts with heat, food and mood.

There is a version of endurance coaching in which the season is organised around a test. Athlete on a treadmill, speed rising in stages, blood taken at each one, a curve plotted, thresholds identified, training paces set from the result. It looks like science and some of it is. The trouble is what happens between tests, which is that the athlete goes and lives in a body that does not hold still.

Blood lactate at a given speed is not a fixed property. It rises when muscle glycogen is low, which means an athlete who trained hard the day before or ate poorly the night before will produce a curve that shifts and a threshold that looks worse than it is. It moves with heat and with hydration. It moves with how much of the working muscle is recruited, which depends on terrain and on shoes and on whether the surface is a treadmill or a track. Two tests a fortnight apart can differ by enough to change every prescribed pace in the programme, and the athlete has not changed at all.

None of this makes the measurement useless. It makes it a single reading of a moving quantity, which is exactly how a sensible coach treats blood pressure or body mass, and exactly how many squads do not treat lactate. The tell is when a training pace derived from a test in March is still being enforced in July, with the athlete quietly aware that it is now either too easy or unreachable.

What I would trust more is the athlete's own report combined with performance in ordinary sessions. If a runner is completing a familiar workout at a familiar pace and finishing it comfortably, that is a better statement about aerobic fitness than any curve, because it is measured in the activity the fitness is for and it is measured every week rather than twice a season.

The honest use of a lactate test is as a rough sorting device early on, to catch the athlete training everything at one intensity, which is a common and expensive mistake.

After that, it mostly reassures the people holding the clipboard.