How does the body utilize lactic acid during prolonged exercise?

During prolonged exercise, lactic acid plays a crucial role in maintaining energy levels. The correct answer highlights that the body converts lactic acid back to glucose in the liver through a process known as gluconeogenesis. This conversion is important because it helps maintain blood glucose levels, which are vital for continued muscle activity and overall energy supply during extended physical exertion.

As muscles work anaerobically and produce lactic acid, this compound can accumulate in the bloodstream. The liver then takes up the lactic acid, where it can be transformed into glucose. This glucose can either be released back into the bloodstream to be used by other tissues or stored as glycogen for future energy needs. This cycle of converting lactic acid back to glucose is part of the Cori cycle, a critical metabolic pathway that supports endurance performance during prolonged activity.

The other options do not align with the physiological processes related to lactic acid during exercise. For instance, the body does not store lactic acid as fat, nor does lactic acid increase muscle strength or induce muscle relaxation directly. Instead, understanding the conversion of lactic acid back to glucose emphasizes the body's remarkable ability to adapt and sustain energy production during extended periods of physical activity.