Biology

Muscle cells undergo lactic acid fermentation during intense exercise.

When muscles are working intensely and oxygen supply is limited, muscle cells switch to lactic acid fermentation to produce ATP quickly. This process allows glycolysis to continue by converting pyruvate into lactic acid, but it can lead to muscle fatigue and soreness.

The other option is incorrect:

NAD+ is a coenzyme that plays a key role in cellular respiration by helping to transfer electrons. However, the accumulation of NAD+ itself does not cause muscle soreness. In fact, NAD+ is continuously recycled during glycolysis and is crucial for energy production....