T. Ledin et Lm. Odkvist, EFFECTS OF INCREASED INERTIAL LOAD IN DYNAMIC AND RANDOMIZED PERTURBED POSTUROGRAPHY, Acta oto-laryngologica, 113(3), 1993, pp. 249-252
Muscular weakness is present in many diseases. The present study attem
pted to model a relative weakness of postural control muscles by loadi
ng the subjects with extra weight, and the effects on EquiTest dynamic
posturography and randomized perturbed posturography were assessed. T
en healthy subjects aged 15-39 years (mean 26 years) were used. Their
weights ranged 53-82 kg. Equilibrium was measured with and without an
extra 20% of body weight attached to the upper part of the trunk by me
ans of pieces of lead metal placed in a specially sewn shirt. Dynamic
posturography (EquiTest) comprises a sensory organization test in whic
h the support surface and visual surround are either stable or referen
ced to the patient's sway, his or her eyes open or closed. In a moveme
nt coordination part the platform makes active movements. Antero-poste
rior sway on a stable support surface with absent or distorted visual
cues was marred, and the correction pattern was altered on a movable s
upport surface when the vision was absent. Furthermore, the EquiTest a
pparatus was driven by special software to produce randomized antero-p
osterior movements during 45 s. In addition to stable conditions, smal
l and large amplitude perturbations were used. The subject's ability t
o remain in equilibrium was estimated by the sway velocity and a confi
dence ellipse sway area during 45 s. During weightbearing, sway areas
were larger on the stable support surface both with and without vision
. Postural sway velocity was lower when vision was absent both using s
mall and large amplitudes. In conclusion, increased inertial load dete
riorates balance on a stable support surface both with and without vis
ion, and makes postural corrections slower when the environment is act
ively moving in absence of vision.