Running a marathon is more than just testing physical endurance; it’s about understanding the body’s biochemical changes. The body undergoes several hormonal and metabolic adjustments to fuel muscles and keep performance steady. This article explains how key hormones and energy sources like insulin, adrenaline, lactate, free fatty acids, and glucose change during a marathon.
Insulin and Blood Sugar Control
Insulin is a crucial hormone for managing blood sugar levels by helping cells absorb sugar from the bloodstream. However, during a marathon, insulin levels drop because muscles use up sugar as they work harder. This use of sugar lowers blood sugar levels. If insulin continued lowering blood sugar in this situation, it could result in dangerously low levels, known as hypoglycemia. To prevent this, the body naturally reduces insulin production.
Adrenaline: Stress Response
Adrenaline, also called the “fight or flight” hormone, stops insulin release and raises blood sugar levels, providing muscles with more energy. During a marathon, adrenaline levels rise, especially around the 30-kilometer mark when sugar stores in the liver and muscles are nearly depleted. Adrenaline triggers actions like converting glycogen to glucose, making glucose from some amino acids, and breaking down stored fats, which help supply muscles with needed energy.
Lactate Buildup and Muscle Fatigue
When muscles lack enough oxygen, they produce lactate. If the body doesn’t clear it efficiently, excess lactate can harm cells. Muscle fatigue during intense activities like marathons is mainly due to lactate buildup. The lactate threshold is the intensity level at which lactate accumulates faster than it can be cleared and is usually reached at 50-80% of an individual’s maximum heart rate, depending on fitness level. Training near this threshold can improve the body’s ability to manage lactate.
Free Fatty Acids and Glucose
Adrenaline helps break down fat to release fatty acids from fat storage. While fat provides less energy per oxygen unit compared to sugar, we have more fat stored. Therefore, our bodies usually use fat for energy and switch to using more sugar during intense exercise. However, converting fat to energy also requires sugar, so it’s crucial to maintain sugar levels. To avoid depleting sugar stores too quickly during a marathon, it’s best to keep a steady and moderate pace.
Conclusion
Understanding the biochemical changes during marathon running sheds light on how the body adapts to physical stress. The coordination between hormones and energy sources illustrates the body’s ability to sustain prolonged exertion. With this knowledge, runners can plan their training and race strategies to enhance performance and endurance.
