Running News Daily

What Happens When the Finish Line Feels 100 Miles Away

We’ve all seen the footage: a runner, sometimes even an elite, staggering or crawling across the marathon finish line. It’s a powerful image—equal parts dramatic and heartbreaking. But what causes those jelly legs, and can it be prevented?

The Science of “Jelly Legs”

The feeling of wobbly or unresponsive legs at the end of a marathon is often the result of neuromuscular fatigue and metabolic depletion. After 26.2 miles, the body’s ability to send signals from the brain to the muscles can falter.

“You’re not just tired,” says Coach Jimmy Muindi, seven-time Honolulu Marathon champion. “Your legs stop responding to what your brain is telling them to do.”

Key Causes

1. Glycogen Depletion

Muscles run on glycogen, and after two to three hours of running, those stores run dry—especially if fueling is inadequate.

2. Dehydration and Electrolyte Imbalance

Even a small loss in body fluid affects muscle function. Electrolyte imbalances (particularly low sodium or potassium) can trigger cramps and weakness.

3. Central Nervous System Fatigue

Your brain gets tired, too. Prolonged effort reduces the brain’s ability to send strong, coordinated signals to the muscles.

4. Improper Pacing

Going out too fast early in the race can lead to full-system shutdown in the final miles. Your body simply can’t hold that pace.

5. Heat and Humidity

Hot races amplify all of the above. Core temperature rises, making it harder for muscles to function efficiently.

Why It Even Happens to Elites

Elite runners push their bodies to the limit. Sometimes a miscalculation in pace, nutrition, or weather adjustment can bring even the strongest athlete to their knees—literally. And because they’re aiming for peak performance, they’re often operating on a knife’s edge.

In 2018, American runner Sarah Sellers nearly collapsed after finishing second at the Boston Marathon, a race defined by brutal weather. Others, like Gabriela Andersen-Schiess in the 1984 Olympics, became iconic for their final, staggering strides.

Prevention Strategies

• Dial in race-day nutrition. Practice fueling with gels, fluids, and electrolytes during training.

• Train your brain. Long runs, heat training, and race simulations help develop mental toughness and delay central fatigue.

• Know your pace. Use race predictors and experience to avoid going out too fast.

• Hydrate smart. Don’t just drink water—replace lost electrolytes.

Final Thought

Marathon running pushes the human body to its limits. Jelly legs and crawl finishes are not signs of weakness—they’re the body’s emergency brake. With smarter training and fueling, most runners can avoid it. But when it does happen, it reminds us how far people will go to finish what they started.

 

(05/09/2025) Views: 176 ⚡AMP
by Boris Baron