Erschienen in:
01.02.2003 | Original Article
Electromechanical assessment of ankle
stability
verfasst von:
Mora Isabelle, Quinteiro-Blondin Sylvie, Pérot Chantal
Erschienen in:
European Journal of Applied Physiology
|
Ausgabe 6/2003
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Abstract
The goal of this study was to approach ankle instability by
measuring the electromechanical delay of the peroneal muscles (foot pronators).
For that purpose, supramaximal electrical stimulation of common peroneal nerve
was applied when the subject was standing on a force plate in bipedal stance or
monopedal stance, postures requiring greater ankle stabilization. The
electromechanical delay (EMD) was defined as the time interval between the
onset of the peroneus longus (PL) electromyogram detected by surface electrodes
and the onset of the lateral ground reaction force (Fy) measured on a force
plate. Ten healthy subjects (control group, C-G) and ten subjects with
functional ankle instability ("FAI" group, FAI-G) performed the tests. In C-G,
the mean EMD values decreased significantly (P<0.001) from the bipedal [10.54 (0.71) ms; mean
(SD)] to the monopedal stance [8.67 (0.63 ms)]. Since a monopedal stance is
known to require higher leg muscle tone resulting in a higher ankle stiffness,
these results indicate that PL EMDs are sensitive to musculo-tendinous
stiffness. They validate the choice of a PL EMD measurement as an indirect
index of musculo-tendinous stiffness at the ankle. In both bipedal and
monopedal stance conditions, EMD values were significantly higher in FAI
subjects. They ranged from 12.64 (1.14) ms in the bipedal stance to 10.85
(1.07) ms in the monopedal stance. This suggests a lower musculo-tendinous
stiffness at the ankle, which may contribute to the ankle instability.