Bi-lateral reactive force patterns in postural sway activity of normal subjects

Abstract

Postural activity of normal subjects while standing still, as measured via the reactive foot-ground reactive forces, was investigated separately for each of the supporting legs, to provide detailed information on the individual activity of each side. Such information is not accessible if the overall reactive forces on the whole body are measured instead. Twenty-three normal adult subjects (average age 41 years) took part in the measuring tests, which were made on two collaterally installed force platforms. From the force traces obtained, the following parameters were determined: timings and amplitudes of the waveforms, separately for each foot and sequence of the force vectors on both feet and in relation to each other. Weight-bearing imbalance was defined in the vertical direction to express the difference between the average forces supported by each of the legs. Two parameters were defined by combining the force results obtained on each of the legs in the horizontal plane: sway total activity, representing the resultant of the added vector-norms in the anteroposterior and mediolateral directions, respectively; and asymmetry, representing the resultant of the subtracted above vector norms. The results indicated that, although the force traces were synchronous to each other, different vectorial force patterns were found, indicating different levels of stabilizing activities on each of the legs. This was also demonstrated by the fact that sway total activity was found considerably higher than the net reactive forces acting on the whole body during sway.(ABSTRACT TRUNCATED AT 250 WORDS)

Dynamic stability differences in fall-prone and healthy adults

“…mean velocity Maki et al, 1990), or area circumscribed by the CoP trajectory (Hasan et al, 1990;Hufschmidt et al, 1980;Maki et al, 1990;Motta et al, 1991), among others. Frequency-domain estimates include a variety of summary statistics describing the spectral distribution of the CoP (Era and Heikkinen, 1985;Maki et al, 1990;Mauritz et al, 1979;Mizrahi and Susak, 1989;Motta et al, 1991). These CoP statistics are often used because they represent the generalized control forces necessary to maintain the center-of-mass (CoM) over the base-of-support (Peterka, 2003;Sliwinski et al, 2004).…”

Use of Stabilometric Platform and Evaluation of Methods for Further Measurments – A Pilot Study

“…This was reported also by different authors (15,17). Some of specific conditions are treated in detail (below).…”

Two-dimensional coherence for measurement of asymmetry in postural steadiness

“…Lower values of 2D-MSC suggest a disorder in the Table 1 Average The most common method to assess symmetry using dual-plate tests of postural steadiness is by tests of weight-bearing imbalance. Weight-bearing imbalance is of value in the assessment of asymmetries of postural control and disease [6,[15][16][17]. Particularly in hemiplegia, weight-bearing imbalance is likely to be of value in the assessment of progress in rehabilitation to increase the use of the hemiparetic limb in standing and walking.…”

“…The use of a two-plate force platform to measure the COP separately under each foot [14] has been shown to be of value in the evaluation of asymmetries in postural control in aging and disease [15][16][17][18]. The most common method has been to quantify the imbalance in weight bearing between the feet.…”