In view of clinical experience of a low-force output in testing
situations in patients with fibromyalgia syndrome (FS), this
study evaluated the possibility of reaching a higher muscular
performance by use of superimposed electrical stimulation: the
tests mainly involved knee-extension in a Kin Com dynamometer.
Twenty-five patients fulfilling the criteria of FS were
compared with 22 healthy subjects. The patients showed a
markedly reduced maximal voluntary contraction, but
superimposed electrical stimulation revealed submaximal
values. The electromyographic activity during stool climbing
exceeded that recorded during maximum voluntary contraction
during the dynamometric test. The cause of the reduced
voluntary maximal performance is discussed.
An impaired control mechanism at a supraspinal level is
suggested. This has to be considered when measuring muscle
strength in FS patients. Tests related to functional
activities are recommended as measures of muscular performance
in this patient group.
Lindh MH, Johansson LG, Hedberg M, Grimby GL