Final answer:
Carb-loading increases muscle glycogen stores, providing a readily available energy source for ATP production during endurance events like marathons.
Step-by-step explanation:
Carb-loading increases glycogen stores in muscles, allowing cells to produce more ATP during a marathon. Glycogen, which is formed from glucose obtained from carbohydrates, serves as an energy reserve in the muscles. During exercise, glycogen can be quickly mobilized and broken down into glucose, which is then converted into ATP through cellular respiration, providing energy for the muscles to perform.
Carb-loading might allow cells to produce more ATP during a marathon because it increases glycogen stores in muscles. This energy reserve can be quickly mobilized to meet the sudden need for glucose, thus sustaining ATP production through cellular respiration during extended exertion. When athlete's carb-load, they eat a lot of starch, which is converted into glucose and then stored as glycogen in the liver and muscle tissues. During a marathon, muscle glycogen is broken down into glucose, which undergoes glycolysis and aerobic respiration to produce ATP.