Question

During high-intensity exercise, muscles primarily get their energy from:

A. Proteins
B. Carbohydrates
C. Fats
D. Nucleic acids

Answer 1

During high-intensity exercise, muscles primarily get their energy from carbohydrates, which are converted into ATP. Proteins and nucleic acids are not primary energy sources during such activities.

Step-by-step explanation:

During high-intensity exercise, muscles primarily get their energy from carbohydrates. Carbohydrates are broken down into glucose, which provides energy as ATP through metabolic pathways like glycolysis and the Krebs cycle. Initially, muscle glycogen is broken down to produce glucose, which then undergoes these processes to produce energy.

As the intensity of exercise increases, and as glycogen stores begin to deplete, the body can convert circulating blood glucose into energy. Fats are also a fuel source but are used more during low to moderate intensity exercises. Proteins and nucleic acids are not primary sources of energy during high-intensity exercise. Proteins may be used when other sources are depleted, but their use can lead to muscle breakdown and body wasting. Nucleic acids are not used as a source of energy for exercise.

Answer 2

During high-intensity exercise, muscles get their energy mainly from carbohydrates. Glycogen stored in muscles is rapidly converted to glucose to generate ATP. Fats and proteins provide energy at a slower rate and are more utilized during lower-intensity activities.

Step-by-step explanation:

During high-intensity exercise, muscles primarily get their energy from the breakdown of carbohydrates. Carbohydrates are the most common source of energy to fuel the body, and during exercise, this macronutrient is vital for ATP production. When you engage in high-intensity workouts, your muscles initially use glycogen stores for quick energy. Glycogen, which is the storage form of carbohydrates within muscles, is converted into glucose, which is then used to generate ATP through anaerobic glycolysis.

While proteins and fats can also provide energy, they do so more slowly and are used more during lower-intensity or endurance exercise. Proteins are not typically a primary energy source, as they are needed for other vital functions such as building and repairing tissues. However, in the case of inadequate carbohydrate and fat intake, the body may resort to proteins for energy, which can lead to muscle breakdown. Similarly, while fats are a significant source of energy, during high-intensity activities, the body primarily relies on the faster conversion of glycogen to glucose rather than the more complex process of breaking down fats into fatty acids for energy.

Nucleic acids, such as DNA and RNA, are not used by the body for energy. They are important for genetic information and cellular processes but not as a direct fuel source during physical activity. Thus, the correct option in the final answer is B. Carbohydrates, since they are the primary source of energy for muscles during high-intensity exercise.