School · Running culture and science · 50 s .
Hitting the wall
Why the marathon gets hard around km 30.
Your muscles store enough glycogen for roughly 90 to 120 minutes of hard running. When it runs low, the body has to rely more on fat, which is slower to use: legs feel empty and pace drops.
That's why the wall often appears between km 30 and 35.
Avoid it with long runs, an even pacing plan and carbohydrate during the race: sports nutrition guidelines suggest about 30 to 90 g per hour, practised in training first.
Fuel early, pace evenly.
Quick check .
Why does the wall happen?
It usually comes between km 30 and 35; long runs, even pacing and race carbs prevent it.