The ongoing aim of this project is to develop a novel, computer- based technique that can be used to delineate, in the human, the neural control and biomechanical mechanisms associated with complex lower extremity motor tasks. Eventually, it is our goal to be able to use this technique to specify the motor coordination strategies that the human central nervous system ought to employ to stand and walk, first in able-bodied persons and later in neurologically- or musculoskeletally-disabled persons. Another goal is to use this technique to assist in the design of patient- specific rehabilitation strategies. Once developed, therefore, this technique may well lead to improved methods of neurological and physical rehabilitation. The computer technique under development is based on optimal control theory, which is highly-developed framework for analysis of complex dynamical systems. However, this theory requires a mathematical formulation of the task to be optimized. One major problem associated with the few previous attempts employing this theory is that the performance criterion cannot be specified with certainty. Our study of maximum jumps and pedaling at high effort circumvents this problem and has let us focus on the development of a mathematical, computer-implemented representation of musculotendon dynamics and musculoskeletal geometry. This representation is needed for computer studies of jumping and pedaling, as well as any motor task involving the lower extremities. The goals are, by using jumping and pedaling as examples of complex motor tasks, to conduct computer studies and experiments: 1. to comprehend how intermuscular coordination, inertial coupling among body segments, musculotendinoskeletal dynamics, and energetics interact to produce synergistic movement; and 2. to understand how muscle strength and speed, elasticity in tendon and muscle, and kinematic constraints affect human coordination and energetics. In contrast to experimental data alone, it is hypothesized that our computer studies will augment one's ability to understand complex movement, such as how and to what degree muscles need to be coordinated, and how limb structure and biomechanical constraints affect coordination.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS017662-09
Application #
3397727
Study Section
Orthopedics and Musculoskeletal Study Section (ORTH)
Project Start
1982-07-01
Project End
1994-06-30
Budget Start
1990-07-01
Budget End
1991-06-30
Support Year
9
Fiscal Year
1990
Total Cost
Indirect Cost
Name
Stanford University
Department
Type
Schools of Engineering
DUNS #
800771545
City
Stanford
State
CA
Country
United States
Zip Code
94305
Van der Loos, H F Machiel; Worthen-Chaudhari, Lise; Schwandt, Douglas et al. (2010) A split-crank bicycle ergometer uses servomotors to provide programmable pedal forces for studies in human biomechanics. IEEE Trans Neural Syst Rehabil Eng 18:445-52
Neptune, R R; Zajac, F E; Kautz, S A (2004) Muscle force redistributes segmental power for body progression during walking. Gait Posture 19:194-205
Zajac, Felix E; Neptune, Richard R; Kautz, Steven A (2003) Biomechanics and muscle coordination of human walking: part II: lessons from dynamical simulations and clinical implications. Gait Posture 17:1-17
Zajac, Felix E (2002) Understanding muscle coordination of the human leg with dynamical simulations. J Biomech 35:1011-8
Zajac, Felix E; Neptune, Richard R; Kautz, Steven A (2002) Biomechanics and muscle coordination of human walking. Part I: introduction to concepts, power transfer, dynamics and simulations. Gait Posture 16:215-32
Kautz, S A; Brown, D A; Van der Loos, H F M et al. (2002) Mutability of bifunctional thigh muscle activity in pedaling due to contralateral leg force generation. J Neurophysiol 88:1308-17
Neptune, R R; Kautz, S A; Zajac, F E (2001) Contributions of the individual ankle plantar flexors to support, forward progression and swing initiation during walking. J Biomech 34:1387-98
Neptune, R R; Kautz, S A (2001) Muscle activation and deactivation dynamics: the governing properties in fast cyclical human movement performance? Exerc Sport Sci Rev 29:76-80
Chen, G; Kautz, S A; Zajac, F E (2001) Simulation analysis of muscle activity changes with altered body orientations during pedaling. J Biomech 34:749-56
Neptune, R R; Kautz, S A (2000) Knee joint loading in forward versus backward pedaling: implications for rehabilitation strategies. Clin Biomech (Bristol, Avon) 15:528-35

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