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How do mitochondria produce ATP for muscle contraction?

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Diagram showing the structure of human striated or skeletal muscle, with labeled cross-sections from whole muscle to fascicle, muscle fiber, myofibril, and sarcomere, highlighting actin and myosin filaments. — muscle The structure of striated, or skeletal, muscle. Striated muscle tissue, such as the tissue of the human biceps muscle, consists of long fine fibers, each of which is in effect a bundle of finer myofibrils. Within each myofibril are filaments of the proteins myosin and actin; these filaments slide past one another as the muscle contracts and expands. On each myofibril, regularly occurring dark bands, called Z lines, can be seen where actin and myosin filaments overlap. The region between two Z lines is called a sarcomere; sarcomeres can be considered the primary structural and functional unit of muscle tissue.

Mitochondria produce adenosine triphosphate (ATP) for muscle contraction through a process called oxidative phosphorylation. This process occurs within the inner mitochondrial membrane and relies on the presence of oxygen.123

The production mechanism involves several key steps:

Substrate Processing: Energy-rich molecules, such as glucose (derived from glycogen) and fatty acids, are broken down through pathways like glycolysis and the citric acid cycle. These reactions generate reduced coenzymes, specifically NADH and FADH $_{2}$ .123
Electron Transport: These coenzymes donate electrons to a series of respiratory chain complexes located on the inner mitochondrial membrane. As electrons pass down this chain, the energy released is used to pump protons (H $^{+}$ ) from the mitochondrial matrix into the space outside the inner membrane.13
ATP Synthesis: This pumping creates an electrochemical gradient (a "transmembrane battery"). When protons flow back into the matrix through the ATP synthase complex, the released energy drives the conversion of ADP and inorganic phosphate into ATP.13

This ATP is then utilized by muscle cells to power mechanical contraction and other energy-demanding processes, such as the active transport of calcium ions.423