Most cells utilize which of the following as their primary source of energy during intense activity?

During intense physical activity, most cells primarily rely on glucose as their main energy source. This is because glucose is readily available in the bloodstream and can be quickly mobilized for energy production through processes such as glycolysis, which is essential for high-intensity exercise.

When the body engages in strenuous activities, such as sprinting or heavy lifting, the demand for energy increases rapidly. Glucose provides a fast and efficient means of generating ATP (adenosine triphosphate), the energy currency of the cell. Glycolysis can occur without the need for oxygen (anaerobic), allowing for quick energy release in short bursts of intense exercise.

While other sources of energy like fatty acids, proteins, and ketones do play roles in energy metabolism, they are not utilized as the primary source during such high-demand situations. Fatty acids are typically broken down for energy during lower intensity or endurance activities, as they require more oxygen and time to metabolize. Proteins can be used for energy but are generally reserved for times of fasting or prolonged exercise when glycogen stores are depleted. Ketones primarily serve as an alternative fuel during prolonged fasting or low-carbohydrate intake, rather than during intense activity.

Therefore, glucose's quick availability and efficient energy