The purpose of this text is to use existing scientific information from previous space flights, space medicine, exercise physiology and sports medicine to prepare a physical fitness manual suitable for use by members of the NASA astronaut population. With the possibility of repeated flights and numerous, diverse, in-flight tasks, the time available for pre-flight conditioning must be utilized as effectively as possible. For the first time, crew members will come from diverse backgrounds and interests. The objective of this text is to provide a variety of scientifically valid exercise programs/activities suitable for the development of physical fitness. An attempt has been made to present programs, activities and supportive scientific data in a concise, easy to read format so as to permit the user to select his or her mode of training with confidence and devote time previously spent experimenting with training routines to preparation for space flight. The programs and activities included in this text have been tested and shown to be effective and enjoyable.