Influence of vision on gait initiation and first step kinematics in young and older adults.

The study investigated whether anticipatory postural adjustments (APAs) of gait initiation and kinematics of the first step are modified with absence of vision in relation to age. Twenty-two young and twenty-two older subjects initiated a self-paced gait with the vision available and deprived. APAs were measured by: (1) force platform and evaluated by maximal amplitude of the center of pressure (CoP) displacements; (2) two inertial sensors attached to the trunk and evaluated by maximal accelerations.

The Effects of Virtual Height Exposure on Postural Control and Psychophysiological Stress Are Moderated by Individual Height Intolerance.

Virtual reality (VR) enables individuals to be exposed to naturalistic environments in laboratory settings, offering new possibilities for research in human neuroscience and treatment of mental disorders. We used VR to study psychological, autonomic and postural reactions to heights in individuals with varying intensity of fear of heights. Study participants ( = 42) were immersed in a VR of an unprotected open-air elevator platform in an urban area, while standing on an unstable ground.

Age-Related Changes of the Anticipatory Postural Adjustments During Gait Initiation Preceded by Vibration of Lower Leg Muscles.

Gait initiation (GI) challenges the balance control system, especially in the elderly. To date, however, there is no consensus about the age effect on the anticipatory postural adjustments (APAs). There is also a lack of research on APAs in older adults after proprioceptive perturbation in the sagittal plane.

Postural stability after treadmill and overground walking in young and elderly.

Background: Ageing commonly disrupts the balance control and compensatory postural responses that contribute to maintaining balance and preventing falls during perturbation of posture. Improvement of compensatory postural responses during walking is one of the main goals in fall prevention programs which often include treadmill walking training. However, during treadmill walking, there is a sensory (visualsomatosensory and vestibular-somatosensory) conflict that can evoke aftereffects of self-motion sensation and could alter postural stability after training.

Parkinson's disease versus ageing: different postural responses to soleus muscle vibration.

Background: Impairments of postural stability occur with increasing age and in neurodegenerative diseases like the Parkinson's disease (PD). While changes in balance have been described in many studies under steady-state conditions, less is known about the dynamic changes in balance following sudden transition to different sensory inputs.

Research Question: The aim was to clarify different effects of age and Parkinson's disease on dynamic postural responses immediately after lower leg muscle stimulation offset.

Postural changes during quiet stance and gait initiation in slightly obese adults.

The study is aimed to examine balance control of slightly obese young adults during quiet stance and during gait initiation with and without crossing an obstacle. Forty-four young subjects were divided in two groups: control (BMI<25 kg/m(2)) and slightly obese (BMI from 25 to 35 kg/m(2)). Center of foot pressure (CoP) and kinematics of fifth lumbar vertebra (L5) were evaluated using a force plate and a motion capture system.

Effect of oral contraceptives intake on postural stability in young healthy women throughout the menstrual cycle.

The purpose of the study was to investigate the effect of oral contraceptives on static postural stability in young healthy women during their menstrual cycle. Twenty-three women with the regular menstrual cycle, using or not using oral contraceptives, participated in this study. Salivary progesterone and estradiol levels were measured during one menstrual cycle.

Breathing changes accompanying balance improvement during biofeedback.

The aim of this study was to determine whether respiration would be altered during visual biofeedback condition while standing on a foam surface. Fifty young, healthy subjects (24 men, 26 women) were divided into a spirometry group, in which additional spirometry analysis was performed, and a control group. All subjects were tested in two conditions: 1) standing on a foam surface and 2) standing on a foam surface with visual biofeedback (VF) based on the centre of pressure (CoP).

Postural stability and responses to vibrations in patients after anterior cruciate ligament surgical reconstruction.

The aim of the study was to evaluate the effect of surgical reconstruction of anterior cruciate ligament (ACL) on postural stability and responses to lower limb (LL) muscles vibrations. Centre of pressure (CoP) was measured in 17 subjects during stance on firm/foam surface with eyes open/closed and during unilateral vibrations of LL muscles (m. triceps surae - TS, m.

Velocity dependence of vestibular information for postural control on tilting surfaces.

Vestibular information is known to be important for postural stability on tilting surfaces, but the relative importance of vestibular information across a wide range of surface tilt velocities is less clear. We compared how tilt velocity influences postural orientation and stability in nine subjects with bilateral vestibular loss and nine age-matched, control subjects. Subjects stood on a force platform that tilted 6 deg, toes-up at eight velocities (0.

Diurnal changes of the postural control in young women without and with hormonal contraceptive treatment.

Objectives: The aim of this study was to investigate diurnal changes of the postural control in young women without and with hormonal contraceptive treatment.

Methods: The postural activity was assessed during stance from two accelerometers positioned at the level of the lumbar (L5) and thoracic (Th4) vertebra in twenty healthy young women non-using (13) and using (7) hormonal contraception.

Results: We observed a significant increase of trunk tilts in the morning in the group of women with hormonal contraception compared to control.

Effectiveness of different visual biofeedback signals for human balance improvement.

The aim of this study was to examine the effectiveness of visual biofeedback (VBF) signals from a force platform and accelerometer sensors placed on different body segments. The study was performed on 20 young subjects during standing on a firm and foam support surface with a VBF signal sensed from CoP, lower trunk (L5) and upper trunk (Th4). The VBF signal was controlled by 2D-movement of chosen body segment, which was presented as a red point on a monitor screen.

Age-related changes in postural responses to backward platform translation.

The aim of the study was to investigate age-related changes in postural responses to platform translation with 3 various velocities. We focused on the influence of linear velocity using the smoothed profile of platform acceleration (till 100 cm.s(-2)).

The age-related changes of trunk responses to Achilles tendon vibration.

The contribution of different sensory modalities to balance control is modified by age. Postural responses to Achilles tendon vibration were investigated in order to understand the influence of age on proprioceptive input from lower legs in human stance. Postural responses to bilateral vibrations of Achilles tendon with 10s duration were recorded at three frequencies (40, 60 and 80 Hz) in 9 healthy young (range, 24-27 years) and in 9 healthy older adults (59-70 years).

Velocity of body lean evoked by leg muscle vibration potentiate the effects of vestibular stimulation on posture.

To investigate the vestibular and somatosensory interaction in human postural control, a galvanic vestibular stimulation of cosine bell shape resulting in a small forward or backward body lean was paired with three vibrations of both soleus muscles. The induced body lean was registered by the position of the center of foot pressure (CoP). During a quiet stance with eyes closed the vibration of both soleus muscles with frequency (of) 40 Hz, 60 Hz and 80 Hz resulted in the body lean backward with velocities related to the vibration frequencies.

Age-related changes of human balance during quiet stance.

Certain aspects of balance control change with age, resulting in a slight postural instability. We examined healthy subjects between 20-82 years of age during the quiet stance under static conditions: at stance on a firm surface and/or on a compliant surface with eyes either open or closed. Body sway was evaluated from centre of foot pressure (CoP) positions during a 50 sec interval.

Effects of linear versus sigmoid coding of visual or audio biofeedback for the control of upright stance.

Although both visual and audio biofeedback (BF) systems for postural control can reduce sway during stance, a direct comparison between the two systems has never been done. Further, comparing different coding designs of audio and visual BF may help in elucidating how BF information is integrated in the control of posture, and may improve knowledge for the design of innovative BF systems for postural control. The purpose of this paper is to compare the effects of linear versus sigmoid coding of trunk acceleration for audio and visual BF on postural sway in a group of eight, healthy subjects while standing on a foam surface.

Human postural response to lower leg muscle vibration of different duration.

Body lean response to bilateral vibrations of soleus muscles were investigated in order to understand the influence of proprioceptive input from lower leg in human stance control. Proprioceptive stimulation was applied to 17 healthy subjects by two vibrators placed on the soleus muscles. Frequency and amplitude of vibration were 60 Hz and 1 mm, respectively.

Somatosensory influence on postural response to galvanic vestibular stimulation.

We investigated how postural responses to galvanic vestibular stimulation were affected by standing on a translating support surface and by somatosensory loss due to diabetic neuropathy. We tested the hypothesis that an unstable surface and somatosensory loss can result in an increase of vestibulospinal sensitivity. Bipolar galvanic vestibular stimulation was applied to subjects who were standing on a force platform, either on a hard, stationary surface or during a backward platform translation (9 cm, 4.

Modification of human postural responses to soleus muscle vibration by rotation of visual scene.

Sensory interaction in posture control in 20 healthy subjects was investigated by postural responses to differently timed proprioceptive and visual stimulation. As proprioceptive stimulation was used both soleus muscles vibration. Visual stimulation was rotating disc moving in forward and backward direction.

Velocity of head movements and sensory-motor adaptation during and after short spaceflight.

To investigate to time course of sensory-motor adaptation to microgravity, we tested spatially-directed voluntary head movements before, during and after short spaceflight. We also tested the re-adaptation of postural responses to sensory stimulation after space flight. The cosmonaut performed in microgravity six cycles of voluntary head rotation in pitch, roll and yaw directions.

Vestibular and somatosensory interaction during recovery of balance instability after spaceflight.

The aim of our contribution was to characterize vestibular and somatosensory influence on human balance recovery during readaptation to the earth conditions after spaceflight. We tested how post-spaceflight postural reactions to galvanic stimulus (related to vestibular input) and to vibration of the lower leg muscles (somatosensory input) were changed.

Vestibular stimulation affects medium latency postural muscle responses.

This study explores whether galvanic vestibular stimulation can alter automatic postural muscle responses triggered 100 ms after surface translations. Our previous study concluded that a step of bipolar, galvanic vestibular stimulation delivered 500 ms prior to a platform translation tilted the internal representation of vertical because subjects' final center of foot pressure and center of mass equilibrium position shifted toward the anode and this tilt was larger than the sum of effects for platform translations and galvanic alone. In the current study, we show that 0.

Human postural responses to different frequency vibrations of lower leg muscles.

We analyzed human postural responses to muscle vibration applied at four different frequencies to lower leg muscles, the lateral gastrocnemius (GA) or tibialis anterior (TA) muscles. The muscle vibrations induced changes in postural orientation characterized by the center of pressure (CoP) on the force platform surface on which the subjects were standing. Unilateral vibratory stimulation of TA induced body leaning forward and in the direction of the stimulated leg.