5'AMP-activated protein kinase (AMPK) is recognized as an important intracellular energy sensor, shutting down energy-consuming processes and turning on energy-generating processes. Discovery of target proteins of AMPK has dramatically increased in the past 10 years. Historically, AMPK was first shown to regulate fatty acid and cholesterol synthesis, but is now hypothesized to take part in the regulation of energy/fuel balance not only at the cellular level but also at the level of the whole organism. In this brief review we will discuss some of the roles of AMPK in skeletal muscle.