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”Classical Heritage” in Motor Control
Edited by Mark Latash
There Is No Motor Redundancy in Human Movements. There Is Motor Abundance
Edited by Mark Latash
It is suggested that the famous problem of motor redundancy is inapplicable to human voluntary movements. Such notions as “the elimination of biomechanical degrees of freedom” should not be used in human movement studies. During natural movements, elements within apparently redundant sets are all involved in solving motor tasks. The abundance of elements is a keystone forming the foundation of motor synergies. It allows natural movements to display both flexibility and stability.
Energy-Minimizing Choices of Muscles and Patterns of Movement
R. McNeill Alexander
Prilutsky (1999, target paper) reports that Crowninshield and Brand's (1981) criterion, minimization of the sum of the cubes of muscle stresses, works well as a predictor of the division of labor between muscles, for various tasks. However, no direct benefit from minimizing this particular sum is apparent, and it seems likely that it is merely a correlate of the criterion that actually drives muscle choice. In many tasks, there would be a clear, direct benefit from minimizing metabolic energy costs, as Prilutsky (1999) points out. Alexander (1997a, 1997b) and Minetti and Alexander (1997) have shown how the metabolic energy costs of muscle contraction can be estimated, and used to predict optimum muscle properties or optimal patterns of movement. This article explores the feasibility of using the same approach to predict optimum division of labor between one- and two-joint muscles.
On Achieving Strong Inference in Prehension Research
Ronald G. Marteniuk and Christopher P. Bertram
Smeets and Brenner have suggested that it may be time to abandon Jeannerod’s “classical approach” to studying human prehension, and have presented a mathematical model as an alternative. We argue that this model provides insufficient grounds for widespread acceptance, and question whether or not such an approach furthers the science of motor control.
