Effects of tendon compliance on the economy of cyclic contractions

Abstract

The use of compliant tendons to store elastic strain energy and release it during the subsequent cycle lowers the mechanical work output and has been suggested to lower the metabolic energy consumed. In this thesis, I examined and compared the activation conditions, work output and force generation of muscle lifting a load an equal distance in the presence of a compliant and non-compliant tendon, and then replicated those movements and activation within an oxygen chamber to test for the differences in energy consumption. It was found that for a single contraction cycle, a cyclically contracting muscle in series with a compliant tendon did less than half of the shortening and lengthening work, nearly twice the net work, resulted in a reduced impulse, required different activation conditions and consumed 17% less energy than a muscle oscillating a load with a non-compliant tendon, suggesting it is responsible for more economical movement.