Carbohydrates play a vital role in endurance performance by providing the body with a readily available source of energy. In IB Sports, Exercise and Health Science (SEHS), carbohydrates are studied to explain how athletes sustain prolonged exercise and delay fatigue. For endurance activities, carbohydrate availability is often the key limiting factor in performance.
During exercise, muscles require a continuous supply of energy to contract. Carbohydrates are broken down into glucose, which is used to produce ATP, the immediate energy currency of the body. When carbohydrate stores are depleted, performance declines rapidly.
Carbohydrates as a Primary Energy Source
Carbohydrates are stored in the body as glycogen, mainly in the muscles and liver. During moderate to high-intensity endurance exercise, glycogen is the preferred fuel source.
Key points include:
- Glycogen provides fast energy
- It supports higher exercise intensities
- It is more efficient than fats for ATP production
As exercise intensity increases, reliance on carbohydrates also increases. This explains why endurance athletes focus heavily on carbohydrate intake before and during competition.
Glycogen Depletion and Fatigue
One of the main causes of fatigue during endurance exercise is glycogen depletion. When muscle glycogen levels fall, the body must rely more on fat metabolism.
This leads to:
- Reduced exercise intensity
- Increased perception of effort
- Difficulty maintaining pace
In IB SEHS, this concept helps explain phenomena such as “hitting the wall” during long-distance events. Once carbohydrate stores are low, performance becomes increasingly difficult to sustain.
Carbohydrates and Exercise Intensity
Carbohydrates are especially important for maintaining moderate to high exercise intensities. While fats provide a large energy reserve, they cannot be broken down quickly enough to support intense effort.
Endurance athletes competing at higher intensities benefit from:
- High pre-exercise carbohydrate availability
- Carbohydrate intake during prolonged exercise
- Effective glycogen replenishment during recovery
These strategies help maintain performance and delay fatigue.
Exam Relevance for IB SEHS
In IB exams, questions on carbohydrates often require applied explanations. Students should clearly link carbohydrate availability to energy production, fatigue, and endurance performance. Using terms such as glycogen, ATP, and exercise intensity strengthens answers.
Carbohydrates also connect to other topics such as hydration, recovery, and training adaptation.
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Frequently Asked Questions (FAQs)
Why are carbohydrates important for endurance exercise?
Carbohydrates provide a fast and efficient energy source that supports sustained muscle contraction and higher exercise intensities.
What happens when glycogen stores run low?
When glycogen is depleted, fatigue increases, exercise intensity drops, and performance declines due to slower energy production.
How are carbohydrates tested in IB SEHS exams?
Questions often focus on energy systems, fatigue, and applied performance scenarios, requiring clear links between carbohydrate availability and endurance.
