The Wall

The psychological and physical barrier around mile 20 of a marathon where quitting feels inevitable.

wallmile 20marathonmental barrierbreaking point

Understanding The Wall

The wall is the sudden, severe physical and psychological barrier most marathon runners experience between miles 18 and 22. It feels like hitting a brick wall mid-stride: your legs become impossibly heavy, your pace plummets, your brain screams "stop," and the remaining miles feel insurmountable.

Physiologically, the wall is primarily glycogen depletion. Your muscles and liver store about 2,000 calories of glycogen — enough for roughly 90–120 minutes of running. For a 4-hour marathoner, glycogen runs out around mile 18–20. When glycogen is depleted, your body switches to burning fat, which produces energy about 50% slower than glycogen. The result: sudden, dramatic fatigue.

The wall is preventable, not inevitable. Three strategies work: (1) Train your body to burn fat more efficiently through long runs and Zone 2 training; (2) Start fueling early and consistently with gels/carbs every 30–45 minutes; (3) Pace conservatively — going out even 10 seconds per mile too fast burns glycogen faster. Marathon veterans who respect these principles rarely hit the wall.

Key Facts: The Wall

Key facts and insights about the wall that every endurance athlete should know.

Typically strikes between miles 18–22 of

Typically strikes between miles 18–22 of a marathon

Caused by glycogen depletion

Caused by glycogen depletion — the body runs out of its preferred fast fuel

Glycogen stores hold ~2,000 calories, en

Glycogen stores hold ~2,000 calories, enough for 90–120 minutes at race pace

Once you hit the wall, recovery during t

Once you hit the wall, recovery during the race is very difficult — prevention is key

Pro Tips: The Wall

Start taking gels at mile 4–5, not when you feel tired — by then it's too late

Run long training runs (18–22 miles) to teach your body to burn fat alongside glycogen

Pace the first 13 miles conservatively — banking time early guarantees paying it back with interest later

When the wall hits, shorten your stride, focus on one mile at a time, and don't stop moving

Frequently Asked Questions About The Wall

No. Many experienced marathoners avoid the wall entirely through proper training, fueling, and pacing. It's most common in first-time marathoners, runners who skip mid-race nutrition, and those who go out too fast. With preparation, the wall becomes a manageable challenge rather than a race-ending catastrophe.

Shorten your stride and slow down (don't stop completely). Take a gel immediately with water. Break the remaining distance into tiny chunks: "just get to the next mile marker." Walking is OK — walk 30 seconds, run 60 seconds, repeat. The wall passes after 1–2 miles if you keep moving and take in calories.