Muscle cells primarily perform aerobic respiration when they have sufficient oxygen available. This is the most efficient way to produce energy (ATP) from glucose.

However, muscle cells can also perform anaerobic respiration when oxygen is limited, such as during intense exercise. This process is less efficient and produces lactic acid as a byproduct, which can contribute to muscle fatigue.

Here's a breakdown:

* Aerobic respiration: This is the preferred method for muscle cells. It involves using oxygen to break down glucose and produce ATP, water, and carbon dioxide. This process is highly efficient and yields the most energy.

* Anaerobic respiration: This process occurs when oxygen is limited. It involves breaking down glucose without oxygen, producing ATP and lactic acid. This process is less efficient than aerobic respiration and produces less ATP.

Therefore, muscle cells primarily rely on aerobic respiration but can switch to anaerobic respiration when oxygen is scarce.