In 1982 Ngok Cheng published, “The Effect of Electric Currents on ATP Generation, Protein Synthesis and Membrane Transport in Rat Skin in Clinical Orthopedics” (volume 171: pages 264-272). This study showed that microcurrent increased ATP production in rat skin by 500%. ATP is the chemical that the body uses for energy. The current also increased amino acid transport into the cell by 70% and waste product removal. The implications for human healing and repair are obvious. ATP production was increased as long as the current was below 500 microamps. When the authors increased the current to 1000 micro amps, or one milliamp, a current range delivered by TENS devices and other types of electrical stimulation therapies, the ATP production was actually reduced.