Mitochondria play a crucial role in muscle cells by producing adenosine triphosphate (ATP), the primary energy currency of the cell. Often referred to as the "powerhouses" of the cell, mitochondria are responsible for cellular respiration, converting nutrients into usable energy. In muscle cells, the demand for ATP increases during physical activity, and efficient mitochondrial function is vital for endurance and strength. This energy production facilitates muscle contraction and overall performance during exercise, highlighting the importance of mitochondria in muscle physiology.