Question

how does muscle contraction use ATP to move actin filaments

Answer 1

Muscle Contraction Requires Large Amounts of ATP Energy

The energy for muscle contraction comes from ATP, which in turn comes from the metabolism of glucose and fatty acids. But so little ATP is actually stored in the muscles that just a few twitches could quickly exhaust the supply. How do muscles overcome this limitation? Although there is little ATP, there is another phosphate compound stored in the muscles, creatine phosphate, which is formed by linkage of a phosphate group to the substance creatine. Creatine phosphate cannot be used directly to power muscle contraction, but it can transfer its phosphate group to ADP to form ATP:

Creatine phosphate + ADP + H+ ---> Creatine + ATP

The newly formed ATP then acts as the direct energy source for contraction. The muscle stores enough creatine phosphate to enable it to contract strongly during the several seconds it takes before the machinery of glycolysis and cellular respiration can produce additional ATP.