The limits of equilibrium in young and elderly normal subjects and in parkinsonians

Schieppati, Marco; Hugon, M; Grasso, Margherita; Nardone, Antonio; Galante, Massimo

doi:10.1016/0013-4694(94)00036-k

Cited by 67 publications

(93 citation statements)

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“…10 min after treadmill walking, the subjective vertical has returned to normal, regardless of vision availability during the stance trials. This recovery may be connected to the mismatch between other sensory inputs that also contribute to the body reference, like vestibular and plantar sole skin aVerents (Duclos et al 2004;Kavounoudias et al 1998), or to the need for reducing the eVort of the leg muscles maintaining the inclined posture (Schieppati et al 1994). …”

Section: Discussionmentioning

confidence: 98%

Quiet stance control is affected by prior treadmill but not overground locomotion

Zanetti

Schieppati

2007

Eur J Appl Physiol

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Treadmill locomotion is different with respect to overground walking and may require an adapted control mode. The relevant neural computational effort may produce lasting effects encroaching upon the performance of a subsequent postural task. The hypothesis of the present study was that, contrary to overground walking, treadmill walking has effects on quiet stance variables, in the assumption that the imposed locomotor activity is more critical to stance control than natural walking. Nine young subjects performed three different walking sessions: treadmill with eyes closed, treadmill with eyes open, overground walking with eyes open. Body sway area and sway path and the position of the centre of foot pressure during stance were recorded by a dynamometric platform under control, post-walking and post-recovery conditions, alternatively with eyes closed and eyes open. At variance with overground walking, treadmill locomotion produced an effect on body orientation in space during the subsequent stance trials. This consisted in a forward inclination of the body, not accompanied by increased body sway, lasting for a few minutes. Presence or absence of vision during treadmill locomotion did not induce differences in the amplitude or time-course of the post-effect. We argue that body inclination would be the consequence of a change in the postural reference produced by a message arising from treadmill locomotion itself, possibly connected to particularities in the control mode of this type of walking.

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Section: Discussionmentioning

confidence: 98%

Quiet stance control is affected by prior treadmill but not overground locomotion

Zanetti

Schieppati

2007

Eur J Appl Physiol

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“…A second explanation for insufficient postural adjustments could be a deficiency in the mechanisms for postural control. 13 This hypothesis does not seem to be able to explain the inadequate postural adjustments noted for the lateral step task in which the equilibrium is never compromised. A third explanation could be a difficulty coordinating two tasks in the course of the same motor act.…”

Section: Cause Of the Deficit In Postural Adjustments In Patients Witmentioning

confidence: 93%

“…[8][9][10] Several hypotheses have been proposed to explain the impairment of gait initiation in patients with PD. It could be a primary deficiency in energizing and producing a movement of sufficient strength, 11,12 a deficiency of postural control, [13][14][15][16] or a defect in coordination between different tasks during the same motor act. Thus, a precise coordination between forward and lateral transfer of the center of gravity and the gait initiation is needed to initiate a step.…”

mentioning

confidence: 99%

Lateral leg raising in patients with Parkinson's disease: Influence of equilibrium constraint

Tonolli¹,

Aurenty²,

Lee

et al. 2000

Mov. Disord.

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“…In contrast, sizeable forward and backward initial standing postures increased CoM displacements respectively in the forward and backward directions. However, a slightly forward leading posture can be considered as the normal human standing posture (Schieppati et al 1994;Gatev et al 1999). Consequently, if the role of APAs is to stabilise the CoM, we should observe a small backward body till before forward arm-raising movement in order to align the CoM vertical projection with the ankle joint axis of rotation.…”

Section: Apas and Com Stabilisationmentioning

confidence: 99%

Simulating mechanical consequences of voluntary movement upon whole-body equilibrium: the arm-raising paradigm revisited

2001

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Voluntary arm-raising movement performed during the upright human stance position imposes a perturbation to an already unstable bipedal posture characterised by a high body centre of mass (CoM). Inertial forces due to arm acceleration and displacement of the CoM of the arm which alters the CoM position of the whole body represent the two sources of disequilibrium. A current model of postural control explains equilibrium maintenance through the action of anticipatory postural adjustments (APAs) that would offset any destabilising effect of the voluntary movement. The purpose of this paper was to quantify, using computer simulation, the postural perturbation due to arm raising movement. The model incorporated four links, with shoulder, hip, knee and ankle joints constrained by linear viscoelastic elements. The input of the model was a torque applied at the shoulder joint. The simulation described mechanical consequences of the arm-raising movement for different initial conditions. The variables tested were arm inertia, the presence or not of gravity field, the initial standing position and arm movement direction. Simulations showed that the mechanical effect of arm-raising movement was mainly local, that is to say at the level of trunk and lower limbs and produced a slight forward displacement of the CoM (1.5 mm). Backward arm-raising movement had the same effect on the CoM displacement as the forward arm-raising movement. When the mass of the arm was increased, trunk rotation increased producing a CoM displacement in the opposite direction when compared to arm movement performed without load. Postural disturbance was minimised for an initial standing posture with the CoM vertical projection corresponding to the ankle joint axis of rotation. When the model was reduced to two degrees of freedom (ankle and shoulder joints only) the postural perturbation due to arm-raising movement increased compared to the four-joints model. On the basis of these results the classical assumption that APAs stabilise the CoM is challenged.

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The limits of equilibrium in young and elderly normal subjects and in parkinsonians

Cited by 67 publications

References 0 publications

Quiet stance control is affected by prior treadmill but not overground locomotion

Quiet stance control is affected by prior treadmill but not overground locomotion

Lateral leg raising in patients with Parkinson's disease: Influence of equilibrium constraint

Simulating mechanical consequences of voluntary movement upon whole-body equilibrium: the arm-raising paradigm revisited

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