The organelle that provides the energy needed for muscle contraction is the mitochondria.

Here's why:

* Mitochondria are the powerhouses of the cell: They are responsible for producing ATP (adenosine triphosphate), the primary energy currency of the cell.

* Muscle contraction requires ATP: Muscle fibers use ATP to fuel the movement of myosin and actin filaments, which are responsible for muscle contraction.

* Mitochondria are abundant in muscle cells: Muscle cells have a high demand for energy, so they contain a large number of mitochondria to meet this need.

So, while muscle cells use glucose and other energy sources, it's the mitochondria that break them down and convert the energy into ATP, which is then used for muscle contraction.