Have you ever reached a point in a marathon where a wave of exhaustion crashes over you, making you feel dizzy and your legs like lead? This sudden fatigue, often experienced around mile 20, is known as ‘hitting the wall’. It’s a common experience in long-distance endurance events like cycling, swimming, and running. But what exactly causes this abrupt decline in energy?
Hitting the wall is a direct result of the body’s depletion of glycogen, a type of glucose stored in liver and muscle tissue. During high-intensity exercise, our muscles rely on glycogen as their primary energy source, breaking it down into glucose to fuel movement. However, our muscles can only store a limited amount of glycogen. This means that as the race progresses, if we haven’t replenished our glycogen stores with food or drink, our bodies start running on empty.
Consider a marathon, which spans 26.2 miles. The average person stores around 1,800 calories worth of glycogen in their muscles and burns roughly 100 calories per mile. This means hitting the wall often occurs around the 18- to 20-mile mark.
The symptoms of hitting the wall are unmistakable: intense exhaustion, muscle cramping, and an increased heart and breathing rate as the body struggles to maintain function. Some individuals might need to slow down and walk for a bit, while others have to stop and rest completely. Regardless, replenishing depleted glycogen stores is crucial.
Several factors can influence how quickly and whether a person hits the wall, including sex, age, and fitness level. A 2021 study revealed that 28% of men hit the wall in a marathon, compared to 17% of women. This could be attributed to men being more likely to overestimate their marathon abilities and run too fast initially.
Professional athletes, due to their extensive experience and tailored training regimens, are less likely to hit the wall. They understand the importance of proper training, incorporating various intensities from slow walks to hill work to encourage heart rate variability. This training approach helps the body learn to utilize fuel efficiently at different intensities while strengthening the heart and lungs.
Gradually increasing mileage also plays a significant role in preventing hitting the wall. By progressively increasing distances, the body adapts and develops the necessary endurance.
Maximizing glycogen stores through proper nutrition and hydration is another crucial aspect. A carbohydrate-rich diet, known as ‘carbohydrate loading’, can help boost glycogen levels. During long races, consuming energy bars or gels every 30 minutes helps replenish glycogen stores, preventing the dreaded wall from hitting.
Understanding and managing glycogen depletion is essential for endurance athletes. By implementing appropriate training strategies, maintaining proper nutrition, and strategically replenishing glycogen stores, athletes can overcome this common challenge and achieve their full potential in long-distance events.
