Steven L. Lehman

In the Motor Control Lab, we ask questions on the human scale, and answer them at the most direct level, from cell to intact person. We use mathematical models to integrate results from the cell to the intact animal. We have investigated questions from the control of the simplest voluntary movements to the rehabilitation of stroke patients by robots. The questions of immediate interest are: How do muscles stop movements? and How does repetitive motion relate to muscle fatigue and to repetitive motion disorders?

A key aspect of the control of voluntary movements and locomotion is force production by muscles that are used as brakes. To find out how muscles act as brakes to stop movements, we do experiments on single muscle fibers in vitro. We characterize the biomechanics of muscle fibers, build mathematical models that simulate those mechanics, and test the models by varying the physical and chemical environment of the fibers. Our research agenda is to characterize force production, energy storage and dissipation, then to extend the fiber model back up to the whole animal scale, iteratively comparing model predictions to experiments at each stage.

With the redesign of workplaces and work, ergonomists have begun to take an interest in fatigue that arises from non-forceful repetitive work. This may be the most common type of fatigue in the modern workplace. Currently we do experiments on intact people to test whether fatigue is an indicator of cumulative repetitive work. This is the first stage in a long term plan to find the connection between fatigue and repetitive motion disorders.