Most of the energy required for muscle contraction is stored as sugar and fat in the body. Normal human activity is dependent on the body’s musculoskeletal system, and muscle contraction is due to the contraction of muscle fibers, an activity that requires energy. For daily life or under the premise of sufficient oxygen, the energy supply of muscle fiber contraction is mainly dependent on the body’s sugar and fat, aerobic oxidation and decomposition of ATP (adenosine triphosphate), so it can be said that most of the energy for muscle contraction from the body’s sugar and fat. In the muscle fiber itself stores a small amount of ATP, these ATP can provide energy for the muscle fiber activity, but the time is very short; if you carry out high intensity or oxygen is not sufficient premise for the activity, the muscle fiber is mainly through the anaerobic fermentation of intracellular myoglycogen to supply energy, but this way is more wasteful of energy, and will produce lactic acid, the body has side effects. For more medical health knowledge, you should consult your physician for guidance, and if you are unwell, seek medical attention in a timely manner.