he major fuel during exercise at 75% Wmax is:Group of answer choicesmuscle glycogenplasma fatty acidsblood-borne glucose

The major fuel during exercise at 75% Wmax is muscle glycogen.

Here's why:

1. When you start exercising, your body first uses the glycogen stored in your muscles for energy.

2. As the intensity of the exercise increases (around 75% Wmax), the body still prefers muscle glycogen as the primary source of energy. This is because glycogen is stored directly within the muscle cells and can be broken down more quickly than fats or blood-borne glucose, providing the fast energy release required for high-intensity exercise.

3. Plasma fatty acids and blood-borne glucose are typically used more during lower intensity, longer duration exercises when the body has more time to break these fuels down for energy.

4. However, as the duration of high-intensity exercise continues, and muscle glycogen stores deplete, the body will increasingly rely on other energy sources, such as plasma fatty acids and blood-borne glucose.

So, in summary, the major fuel during exercise at 75% Wmax is muscle glycogen.