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Annu Rev Physiol., 1979; 41: 99-114

Regulation of stiffness by skeletomotor reflexes

Year: 1979

Houk JC
Department of Physiology, Northwestern university medical and Dental Schools, Chicago


Since the early 1950s when Merton introduced his "follow-up serco hypothesis" of movement control, the dominant optinion has held that strech and unloading reflexes function to control the length of a muscle in opposition to changes in mechanical load, thus providing load compensation. In this article I review recent evidence incidating that this notion is wrong, or at least incomplete, and proceed to develop an alternative idea that neither muscle length nur force are regulated as individual variables, but that a property called stiffness (the ratio of force change to length change) is maintained relatively constant by skeletomotor reflexes. This leads to a discussion o fthe actions of decending motor commands on the segmental system, from which I conclude that these may be much less versatile than was formaly believed.

GID: 84; Last update: 16.12.2007
More information: Original Article