A new study has just looked into what 'Hitting the Wall' actually involves. Hitting the wall (HTW) is a term used across lots of endurance sports (though cyclists, for some reason, prefer 'The Bonk') to describe the point at which your body just seems to quit. For most marathon runners it seems to kick in around the 30km mark.

It was long thought to be a drop in glycogen, muscle fuel, that caused it. But a study of almost 300 mature (mean age 48–51) marathon runners in Japan points to 3 types of on-the-day performance, and it may be as much mechanical as chemical.

You can read the whole study on the link below, but they found 3 groups: those that kept a steady pace for the whole race, those that gradually slowed from 15k and those that HTW at 30K. They were all tracked with wrist trackers that logged pace, step length, step frequency, ground-contact time, vertical motion, and vertical stiffness for every kilometer.

It seems that a lack of vertical 'stiffness' was a key component in both the groups that slowed down but it dropped dramatically at the 30K point for those that HTW. This suggests vertical stiffness may be a lever worth training, separate from fuelling. Our feed is always full of people advocating for 'tendon stiffness', 'muscle stiffness' or whatever the current term for spring is. You can think of it as the ability that we train through plyometric work like hops, bounds, depth jumps and the like. Loading the muscle before using it for an explosive movement like jumping.

Correlation / causation is an issue but if you are marathon training then plyo work might be a good addition, as well as the usual good fueling and pacing to ensure you hit the 30k mark with some spring left in the legs.

Full study here.