Running downhill is the session your programme is missing

Braking loads tear muscle in a way flat mileage never does, and courses with descents punish anyone who has not rehearsed them.

Anyone who has raced a course with a long descent in the first half knows the feeling at twenty miles: quads that will not fire, a stride that has gone short, and no obvious reason, because the effort felt easy at the time.

That is the point. Downhill running loads muscle while it is lengthening. The quadriceps is not pushing you along so much as resisting the fall, absorbing each landing, and that kind of contraction produces far more mechanical disruption per unit of effort than the pushing kind. Your breathing is comfortable. Your heart rate is low. The bill is being run up anyway, in a currency your usual monitoring does not track at all.

Which is why a course with early descents is dangerous in a way that a course with early climbs is not. The climb tells you what it costs. The descent hides it, collects later, and by the time you feel it there is nothing to be done, because damaged muscle does not recover mid-race.

The fix is exposure and it is boringly effective. Repeated bouts of downhill running produce a protective effect that lasts weeks, so the same session done a second time causes markedly less soreness. Anyone racing a descending course should be doing a handful of controlled downhill efforts in the weeks beforehand, on a moderate grade, at a pace that is honest rather than reckless, and then leaving enough time to be recovered.

Almost nobody does. The sessions look pointless on a training log, they generate no impressive splits, and they leave you sore for three days, which feels like a cost with no product.

There is a technique element as well, and it is worth more than most people think. Runners brake going downhill because they are frightened, landing heel first with a straight leg well ahead of the body, which maximises exactly the loading they should be minimising. Shorten up, increase the turnover, keep the foot closer to underneath you, and let the hill do some of the work.

Faster and cheaper at the same time. There are not many of those in this sport, and it is strange how few people take this one.