Sources of ATP include the phosphorylation of ADP by creatine phosphate, anaerobic glycolysis, and oxidative phosphorylation of ADP n the mitochondria.
If muscle contractions use ATP at or below the maximum rate of ATP generation by mitochondria, the muscle fiber will be able to sustain the contraction for a longer period without fatigue, as the ATP production can meet the energy demands of the muscle activity.
ATP
The most abundant source of energy in a muscle fiber is adenosine triphosphate (ATP), which is used to power muscle contractions. ATP is generated through processes like glycolysis and oxidative phosphorylation in the mitochondria.
A single muscle cell is called a muscle fiber.
fiber does not supply energy to humans , as it is not digested by humans ,the reason being that humans do not have enzymes that can digest fiber .
Each muscle fiber is also called a myofiber.
Myofibril
It is not the muscle but the muscle fiber which works for when recruited for long duration. The red muscle fiber or the slow twitch fiber gets recruited for long term stress on the muscle for example if you do bench press on heavy weight explosively for 5 reps you extensively use fast twitch fibers but if you do bench flys for 15 reps in controlled fashion, you extensively use red fibers.
make more muscle fiber
Since the mitochondria produces energy and the muscle cells are part of the mitochondria, they use the energy so they can move the joints.
muscle fiber
a muscle fiber