The type of substrate used during exercise is dependent on a number of factors s

Question

The type of substrate used during exercise is dependent on a number of factors such as duration and intensity of exercise, and substrate availability. Which of the following statements about substrates utilization during exercise is/are the most correct?

a. 3 & 4           1. While it has been shown that sports drinks can enhance short duration high intensity exercise, there is very little evident to suggest that carbohydrate drinks improve performance during endurance events lasting greater than 90 minutes.
b. 1, 2 & 3       2. During low to moderate intensity steady state exercise lasting greater than 30minutes, there is a gradual shift from fat metabolism towards carbohydrate metabolism.
c. 2 & 5           3. In general, the contribution of protein to energy metabolism is very small except during the final minutes of greatly prolonged exercise bouts lasting more than 3-5 hours.
d. 3, 4 & 5       4. During high intensity exercise, the majority of carbohydrate metabolism for energy comes from the muscle glycogen.
e. 2, 3 & 4       5. Since fat is only stored under the skin and around vital organs, the working muscles are dependent on plasma free fatty acids (FFA) as the only source of triglycerides.

Please provide explination

Explanation / Answer

As exercise intensity increases (eg, to moderate running), plasma fatty acid turnover does not increase and the additional energy is obtained by utilization of muscle glycogen, blood glucose, and intramuscular triglyceride. Further increases in exercise intensity are fueled mostly by increases in muscle glycogen utilization with some additional increase in blood glucose oxidation. Muscle glycogen and blood glucose contribute equally to carbohydrate energy production over 2-3 h of moderate-intensity exercise.The relative contribution of these major substrates to the total body metabolism depends on factors such as the intensity and duration of the exercise, the diet consumed on the days before the exercise, and the state of physical training. With light prolonged exercise there is a progressively greater use of fat until it can contribute up to 80% of the total caloric expenditure .However, the relative contribution of fat to the metabolism is less and that of carbohydrate greater as exercise intensity increases. Consumption of a diet rich in fat and protein produces a shift toward a greater use of fat with a concomitant reduction of both the intensity and duration of effort that can be sustained. Conversely, ingestion of a carbohydrate-rich diet increases the percentage of carbohydrate used and increases endurance.

So answer is E. 2 , 3 , 4.

Exercise for short duration will burn the fats as fuel and later on increasing the intensity and duration of action carbohydrates are used. Proteins are very less used instead fats and carbohydrates are burntDuring low-intensity cardiovascular exercise, fats are your muscles' primary fuel. They provide a slow-burning, long-lasting energy souce.

Carbohydrates

As exercise intensity increases, carbohydrates form a larger part of your muscles' fuel mix. Carbs don't contain as much energy as fat, yielding only 4 calories per gram.

Protein

Although you can metabolize proteins for energy, your body generally prefers to use fats and carbs, sparing proteins for other purposes, such as building muscle and bone. However, during long-duration cardiovascular exercise, your muscles may supplement their energy needs by metabolizing the building blocks of proteins, known as amino acids.

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