Skeletal muscles can use both aerobic and anaerobic respiration to produce the atp needed for muscle contractions. skeletal muscles can also stockpile a small amount of atp and another molecule, phosphocreatine (pcr), that can be used to convert adp into atp quickly without having to use either form of respiration. in prolonged exercise, such as swimming, all three of these processes are used to supply atp for muscle contraction. what is the correct order in which processes are used in the muscle cells during a prolonged swim?