RT Journal Article SR Electronic T1 Muscular Force in Running Turkeys: The Economy of Minimizing Work JF Science JO Science FD American Association for the Advancement of Science SP 1113 OP 1115 DO 10.1126/science.275.5303.1113 VO 275 IS 5303 A1 Roberts, Thomas J. A1 Marsh, Richard L. A1 Weyand, Peter G. A1 Taylor, C. Richard YR 1997 UL http://science.sciencemag.org/content/275/5303/1113.abstract AB During running, muscles and tendons must absorb and release mechanical work to maintain the cyclic movements of the body and limbs, while also providing enough force to support the weight of the body. Direct measurements of force and fiber length in the lateral gastrocnemius muscle of running turkeys revealed that the stretch and recoil of tendon and muscle springs supply mechanical work while active muscle fibers produce high forces. During level running, the active muscle shortens little and performs little work but provides the force necessary to support body weight economically. Running economy is improved by muscles that act as active struts rather than working machines.