See calisthenics in American Heritage Dictionary 4
(kălˌĭs-thĕnˈĭks)
noun
(used with a pl. verb) Gymnastic exercises designed to develop muscular tone and promote physical well-being: Sit-ups, trunk twists, and other calisthenics are demonstrated on the videotape.
(used with a sing. verb) The practice or art of such exercises: Calisthenics is recommended to relax the muscles before a run.