Nature of passive musculoarticular stiffness increase of ankle in female subjects with fibromyalgia syndrome.

The objective of this study was to assess the passive elastic and viscous stiffness components of ankle in young, middle-aged and old adult female fibromyalgia subjects and compare the results with age-matched healthy control subjects. The passive musculoarticular stiffness of the ankles of 60 fibromyalgia subjects and 52 controls was quantified by measuring the ankle resistance to imposed sinusoidal rotary displacements at nine different oscillation frequencies. For each frequency, the resulting torque response of the ankles was decomposed into elastic and viscous components of the total stiffness. The self-perceived stiffness intensity of the ankles was assessed in fibromyalgia subjects by means of a visual analogue scale. Two-way ANOVA test indicated a significant effect of fibromyalgia (P < 0.001) and age (P < 0.001) on elastic stiffness results and a significant effect of age (P < 0.001) on viscous stiffness results. Post hoc Holm-Sidak test indicated that younger and middle-aged fibromyalgia subjects had a significant elastic stiffness increase of more than two times that of controls (P = 0.038 and P < 0.001, respectively). Middle-aged fibromyalgia subjects had a significant viscous stiffness increase of 1.2 times that of controls (P = 0.038). No significant differences in stiffness were observed between older fibromyalgia subjects and controls. In conclusion, the self-perceived stiffness increase of ankle reported by younger and middle-aged fibromyalgia subjects is due to changes in elastic and/or viscous musculoarticular structures around the ankle. The absence of changes in older fibromyalgia subjects is probably related to the ageing process of controls.

RCT Entities:   Population Interventions Outcomes