Tendon force measurements and movement control: a review.

Knowledge of the mechanical and electrical output from skeletal muscle is of interest to investigators from several disciplines including physiology, biomechanics, neuroscience, orthopedics, and physical rehabilitation. Estimates of muscle output (i.e., force) have generally been made using indirect calculations. Forward solution (e.g., EMG) and optimization models have recently been developed using a wide variety of input parameters to estimate force output of individual muscles. These estimates, however, have lacked comparison values necessary for validation. In vivo measurements of muscle force have been made in both animals and humans using a "buckle" type tendon transducer surgically implanted on the tendons of the muscles under study. Investigations utilizing these transducers have addressed a wide range of questions regarding muscle function. This review examines the use of this technology and discusses the significance of the future use of "buckle" transducers in studies exploring load sharing among muscles and in the validation of existing models that estimate muscle force.