The eight hundred metres is not a percentage split

Coaching the two-lap event from a textbook ratio of aerobic to anaerobic contribution produces sensible training and mediocre racing.

Every middle distance coach has seen the figure. The 800 metres is roughly sixty per cent aerobic and forty per cent anaerobic, or the other way round depending on which decade the textbook was printed in, and from that number a whole training week gets built. Some threshold work, some lactate tolerance work, the ratio balanced like a recipe.

The figure is not wrong. It is just useless.

It is a population average measured in laboratory conditions across a spread of athletes who ran the race in different ways, and averaging them washes out the only thing a coach needs to know, which is what kind of runner is standing in front of them. A 400 metre runner moving up and a 1500 metre runner moving down can produce the same time in the same race and arrive there through entirely different physiology. Feed both of them the average and you have made one of them worse.

The other problem is that the split is a description of the finished race, not a prescription for it. Energy contribution is a consequence of pace distribution. Go out in fifty two seconds and you have chosen a heavily anaerobic race whether that suits you or not, because you have committed to holding on through a state you created in the first lap. Go out in fifty six and the same body runs a different race. The ratio did not choose the tactics. The tactics chose the ratio.

Which is why I think the useful question is not what percentage of the energy comes from where. It is a simpler and more uncomfortable one. How badly does this athlete decay in the last hundred and twenty metres, and what causes it in them specifically. For some it is a stiffening, mechanical failure where the stride collapses and the arms start climbing. For others the mechanics survive and the athlete simply cannot recruit anything more.

Those two runners need opposite winters. One needs speed reserve so that race pace sits further below their maximum. The other needs the capacity to keep producing under acidosis, and that is grim, specific, low-volume work you can only do a handful of times a month.

The ratio cannot tell you which is which. Watching the last home straight can, and it is free.