Final answer:
Runners eat large servings of pasta and bread the day before a race as part of a strategy called carb-loading. This helps increase glycogen stores and provides a sustained source of energy during the race.
Step-by-step explanation:
A runner eats large servings of pasta and bread the day before a race because it is part of a strategy called carb-loading. Carbohydrates are the body's main source of energy, and by consuming a high-carbohydrate meal before the race, the runner increases their glycogen stores. Glycogen is a form of stored glucose that can be quickly converted into energy during exercise. By having more glycogen available, the runner will have more energy to sustain their performance throughout the race.
Additionally, pasta and bread are easily digested and provide a steady release of glucose into the bloodstream. This helps maintain blood sugar levels and provides a sustained source of energy during the race.
It is important to note that the timing of carbohydrate consumption is also important. Consuming simple sugars a few hours before the competition can provide a quick boost of energy, while eating a large pasta dinner the night before ensures the body has enough time to fully digest and store the carbohydrates as glycogen.