Recent studies have demonstrated that spastic stroke
patients have normal reflex stiffness of the ankle extensors,
but the muscles themselves are stiff intramuscularly, which
altered the intra- and extra-muscular supporting structures
(Sinkjaer et al., 1993; Sinkjaer and Magnussen, 1994). In
addition, Fride´ and Lieber (2003) suggested that spastic
muscle cells are shorter and stiffer than normal cells.