EurekAlert! -- Peripheral artery disease (PAD) affects 5 million individuals in the U.S. and is the leading cause of limb amputations. Doctors have long considered exercise to be the single best therapy for PAD, and now a new study helps explain why. Led by researchers at Beth Israel Deaconess Medical Center and published in this week’s Online Early Edition of the Proceedings of the National Academy of Sciences (PNAS), the findings demonstrate that a protein called PGC-1alpha plays a key role in the process.