This volume presents the proceedings of a muscle symposium, which was held as the Fourth Fujihara seminar on October 28 - November 1, 2002, at Hakone, Japan. This volume covers all fields of muscle biology, from molecules to humans. This book provides information about recent progress of muscle research as well as the problems that remain to be investigated. This volume will stimulate muscle investigators to design and perform novel experiments to clarify the mysteries in muscle contraction.