AN INTEGRATIVE FRAMEWORK LINKING ANKLE MUSCLE- TENDON MECHANICS & ENERGETICS DURING HUMAN LOCOMOTION

Final Science Report for the BSF Project: AN INTEGRATIVE FRAMEWORK LINKING ANKLE MUSCLE-TENDON MECHANICS AND ENERGETICS DURING HUMAN LOCOMOTION 1 2Raziel Riemer and Gregory S. Sawicki (application number: 2011152) 1.

Dept. of Industrial Engineering and Management, Ben-Gurion University of the Negev, Beer-Sheva, Israel 2.

Dept. of Biomedical Engineering, North Carolina State University, Raleigh, North Carolina, USA EXECUTIVE SUMMARY: During walking and running, mechanical work performed at the lower-limb joints is shared by both muscles and tendons. These dynamic muscle-tendon interactions make it difficult to relate muscle force and work production to the metabolic cost of locomotion. Our goal was to use a multifaceted approach (in silico, in vitro and in vivo) to study muscle force and work production in the human plantarflexors and relate these mechanical measures to metabolic energy expenditure during human locomotion (i.e., single-joint bouncing/hopping and walking up, down and on the level).

To accomplish this we developed a novel theoretical/experimental framework employing a combination of techniques to study human bouncing/hopping and walking with and without elastic ankle exoskeletons. Using musculoskeletal models and simulations, human locomotion experiments that include real-time ultrasound imaging techniques and in vitro isolated muscle-tendon experiments than enable direct measures of force and work our studies demonstrate, in general, that the predominant driver of metabolic energy consumption in the plantar flexors is generation of mechanical force, not work.

Our results have generated a MS thesis, six published journal articles and two manuscripts in preparation for submission. These works will (1) form the foundation for a muscle-level understanding of the relation between mechanics and metabolic cost of locomotion (2) provide data that can be used to drive more complex computer models of human locomotion and (3) motivate better designs for wearable robots (e.g.

prostheses and exoskeletons).