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The present study aimed to investigate the sensitivity of detecting lower limb passive motion and use of additional sensory information from fingertip light touch for the postural control of older adults in comparison with young adults. A total of 11 older and 11 young adults (aged 68.1 ± 5.2 and 24.2 ± 2.2 years, respectively) underwent two tasks. We evaluated their sensitivity to passive ankle joint movement while seated in the first task. Participants then stood quietly on a force plate in a semi-tandem stance, for 30 s under two fingertip contact force conditions (no touch and light touch limited to 1 N). The results showed that the threshold of passive ankle displacement and body sway is higher in older adults than in young adults. The body sway reduced for both older and young adults with the addition of light touch at the fingertips. The maximum cross-correlation coefficient and time lags between body sway and fingertip light touch center of pressure was similar between both groups, suggesting that older adults used light touch to reduce body sway, similar to young adults. A higher threshold in detecting passive ankle joint movement may contribute to the increased body sway observed in older adults. These deficits may be compensated by additional sensory cues that would provide enhanced information used to control the upright stance., (Copyright © 2018. Published by Elsevier B.V.)

The application of subsensory noise stimulation over the lower limbs has been shown to improve proprioception and postural control under certain conditions. Whereas the effect specificity seems to depend on several factors, studies are still needed to determine the appropriate method for training and rehabilitation purposes. In the current study, we investigated whether the application of subsensory electrical noise over the legs improves proprioceptive function in young and older adults. We aimed to provide evidence that stronger and age-related differential effects occur in more demanding tasks. Proprioceptive function was initially assessed by testing the detection of passive ankle movement (kinesthetic perception) in twenty-eight subjects (14 young and 14 older adults). Thereafter, postural control was assessed during tasks with different sensory challenges: i) by removing visual information (eyes closed) and; ii) by moving the visual scene (moving room paradigm). Tests performed with the application of electrical noise stimulation were compared to those performed without noise. The results showed that electrical noise applied over the legs led to a reduction in the response time to kinesthetic perception in both young and older adults. On the other hand, the magnitude of postural sway was reduced by noise stimulation only during a more challenging task, namely, when the optical flow was changing in an unpredictable (nonperiodic) manner. No differential effects of stimulation between groups were observed. These findings suggest that the relevance of proprioceptive inputs in tasks with different challenges, but not the subjects' age, is a determining factor for sensorimotor improvements due to electrical noise stimulation., (Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.)

Objectives: The response time (RT) to kinesthetic perception has been used as a proprioceptive measurement, for example, in older individuals. However, the RT cannot provide information on impairments at specific stages of the respective sensorimotor processing. In the present study, electroencephalographic (EEG) signals were recorded during passive ankle movement with and without an associated perceptual task of movement detection. The main purpose was to analyze differences between young and older adults both in terms of RT and cortical responses. Putative differences in the latter were expected to point to changes in the processing associated with neural pathways or cortical regions in the older subjects., Methods: The EEG activity of nineteen older (OA, 65-76 years) and 19 young adults (YA, 21-32 years) was recorded during passive ankle movement, without motor voluntary response (NVR, sensory condition), and during a condition with voluntary motor response (VR, with measurement of the RT). Event-related potentials (ERP) and beta event-related desynchronization/synchronization (ERD/ERS) were recorded and analyzed in both experimental conditions., Results: The RT in OA was larger than in YA (P<0.0001). EEG analyses showed that the N1 amplitude was larger in the VR than in the NVR condition (P=0.006), whereas no difference for latency was obtained between conditions (P=0.376). Comparisons between the groups revealed attenuated (P=0.019) and delayed (P=0.001) N1 in the OA group, irrespective of the condition (no interaction group vs condition). Only OA showed correlations between RT and N1, with significant correlation for both amplitude (r=-0.603, P=0.006) and latency (r=0.703, P=0.001). The ERD/ERS analyses revealed a task-dependent group effect: in NVR, significant differences were obtained only for the ERS amplitude, which was attenuated in OA (P=0.003). In VR, larger (P=0.004) and delayed (P=0.003) ERD and attenuated (P=0.029) and delayed (P=0.017) ERS peaks were observed in the older group., Conclusions: The results suggest that a larger response time to proprioceptive stimuli in older adults is associated with a weaker and delayed proprioceptive afferent inflow to the cortex. In this scenario, older adults would need a higher cognitive effort (larger ERD) to process the sensory inputs when attempting to properly perform a sensorimotor task., Significance: ERP and ERD/ERS measurements during kinesthetic assessment provide new insights on identification of the origin of sensorimotor slowing in older adults., (Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.)

Patterns of adaptive changes to the exposure to a sinusoidal visual stimulus can be influenced by stimulus characteristics as well as the integrity of the sensory and motor systems involved in the task. Sensorimotor deficits due to aging might alter postural responses to visual manipulation, especially in more demanding tasks. The purpose of this study was to compare postural control between young and older adults at different levels of complexity and to examine whether possible sensory and/or motor changes account for postural performance differences in older adults. Older and young adults were submitted to the following tests: postural control assessments, i.e., body sway during upright stance and induced by movement of a visual scene (moving room paradigm); sensory assessments, i.e., visual (acuity and contrast sensitivity) and somatosensory (tactile foot sensitivity and detection of passive ankle motion); and motor assessments, i.e., isometric ankle torque and muscular activity latency after stance perturbation. Older adults had worse sensory and motor performance, larger body sway amplitude during stance and stronger coupling between body sway and moving room motion than younger adults. Multiple linear regression analyses indicated that the threshold for the detection of passive ankle motion contributed the most to variances in body sway and this contribution was more striking when visual information was manipulated in a more unpredictable way. The present study suggests that less accurate information about body position is more detrimental to controlling body position, mainly for older adults in more demanding tasks.

The purpose of the present study was to examine how children's postural control is affected by different visual cues. Sixteen children, ages 8 and 12 years, and eight adults participated in the study. Each was asked to stand upright inside a moving room, which oscillated at 0.2 Hz, while facing the frontal wall at two distances: 75 and 150 cm, under monocular and binocular vision conditions. Vision manipulation induced corresponding body sway in all participants, but vision effect was the smallest in the monocular vision condition, at the greater distance (150 cm) from the front wall. More importantly, however, the influence of visual manipulation on body sway was age-dependent, with the younger children showing less visually induced body sway than the older children and adults. This aging effect was more dramatic in the monocular vision condition. These results suggest that development of the visual system is not fully completed until the age of 12 years and that eye movement and binocular vision might play an important role in how visual cues are coupled to body sway.

The aim of the study was to examine how individuals of different ages react to forward balance perturbations. Thirty-six volunteers, divided into four groups [young (YA), middle-age (MA(40) and MA(50)), and old (OA) adults], stood on a platform that was either kept stationary, moved backward, or moved forward. EMG onset, EMG time-to-peak, iEMG, and agonist-antagonist co-activation, as well as cumulative angular excursion, maximum center of mass (CM) backward displacement, and CM time-to-reversal were assessed after forward translations. Postural synergies were assessed using principal component analysis (PCA). The results showed that OA activated their muscles later than YA [TA=25 ms, RF=17 ms] and OA and MA(50) reached the peak of activation later than YA [MA(50):TA=23 ms, RF=32 ms, OA:TA=28 ms, RF=21 ms]. Moreover, OA kept a higher level of activation longer than all younger groups. No differences among groups were observed in co-activation, kinematic, and PCA variables. We conclude that changes in temporal EMG patterns can be seen in the fifth decade. However, such changes have no effect on the CM horizontal displacement and CM time-to-reversal after perturbation, which cannot be justified by the use of different postural synergies, suggesting that temporal aspects of muscle activation could play a minor role in controlling excessive CM displacements after perturbations., (Copyright (c) 2009 Elsevier Ltd. All rights reserved.)

The aim of this work was to compare cortical beta oscillatory activity between young (YA) and older (OA) adults during the assessment of ankle proprioception. We analyzed the response time (RT) to kinesthetic perception and beta event-related desynchronization/synchronization (ERD/ERS) in response to passive ankle movement applied at a slow speed, 0.5°/s. The relationship between ERD/ERS and RT was investigated by classifying the signals into fast-, medium-, and slow-RT. The results showed a temporal relationship between beta oscillation changes and RT for both groups, i.e., earlier ERD and ERS were obtained for trials with faster response time. ERD was larger and delayed in OA compared to the YA, and beta ERS was present only for OA. These findings suggest that a less efficient proprioceptive signaling reaching the brain of OA requires a higher level of brain processing and hence the differences in ERD potentials between YA and OA. Furthermore, the occurrence of ERS in OA might represent a compensatory strategy of active cortical resetting for adequate sensorimotor behavior due to the age-related reduced peripheral input and neuromuscular impairments. Altered balance between excitatory and inhibitory intracortical activity in older adults presumably explains the changes in beta oscillations. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to compare the performance of the sensory and motor systems and the contributions of possible differences to postural control. Methods: Twenty older adults (68.9±3.7 years of age) and twenty young adults (21.9±2.1 years of age) underwent visual, somatosensory (tactile and kinesthetic sensitivity), motor tests (joint torque and muscle activation latency) and postural control assessments (upright semi-tandem posture). Results: MANOVA and ANOVA indicated that older adults had a poorer performance in the sensory tests: visual acuity (p=0.001), visual contrast sensitivity (p=0.009), tactile sensitivity (p<0.001) and kinesthetic sensitivity of the knee (p<0.001) and ankle (<0.001); and in the motor tests: female (p=0.010) and male (p<0.001) knee flexion torque; female (p=0.002) and male (p<0.001) knee extension torque; female (p=0.029) and male (p=0.006) ankle dorsiflexion torque; female (p=0.004) and male (p=0.004) ankle plantar flexion torque; and muscle activation latency (p<0.001 ). The older adults also had greater body sway amplitude on the anterior-posterior direction (p=0.035). Multiple regression analysis revealed that perception of passive motion was the only variable that contributed to greater body sway on the anterior-posterior direction among older adults (R2=0.142; p<0.05). Conclusions: There are differences in sensory and motor performance between young adults and older adults, and attention should be directed toward the contribution of the proprioceptive system to postural control among older adults. [ABSTRACT FROM AUTHOR]

Background: Ageing is characterized by a number of physical changes that contribute to a decline in the ability to perform daily tasks. Stretching has been proposed to reduce hip flexion contracture and increase hip and pelvis range of motion, thus improving gait performance. Objective: The purpose of this study was to determine whether a supervised stretching program designed to improve the range of motion of the lower limbs alters gait kinematics in older adults. Methods: Twenty healthy older adult women (65.9 ± 4.2 years old and BMI 24.9 ± 3.5) were divided into 2 groups. The experimental group undertook 12 sessions of stretching exercises, whereas the control group did not engage in any physical activity. Gait performance was assessed at the beginning of the experiment and after the 4-week intervention period. Results: Those in the experimental group showed increased step length, higher velocity and reduced double support time after training. In addition, participants involved in the stretching program showed greater anterior and lateral pelvis tilt and also greater rotation (p < 0.05). Conclusions: Based on our results, we can suggest that a supervised stretching program is effective to alter a number of gait variables. Moreover, after the stretching protocol, aged participants displayed gait parameters which were similar to those reported in young healthy adults. Therefore, stretching can be used as an effective means to improve range of motion and reverse some age-related changes that influence gait performance. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Aging is characterized by a decline in the postural control performance, which is based on a coherent and stable coupling between sensory information and motor action. Therefore, changes in postural control in elderlies can be related to changes in this coupling. In addition, it has been observed that physical activity seems to improve postural control performance in elderlies. These improvements can be due to changes in the coupling between sensory information and motor action related to postural control. Objective: The purpose of this study was to verify the coupling between visual information and body sway in active and sedentary elderlies. Methods: Sixteen sedentary elderlies (SE), 16 active elderlies (AE) and 16 young adults (YA) were asked to stand upright inside a moving room in two experimental conditions: (1) discrete movement and (2) continuous movement of the room. Results: In the continuous condition, the results showed that the coupling between the movement of the room and body sway was stronger and more stable for SE and AE compared to YA. In the discrete condition, SE showed larger body displacement compared to AE and YA. Conclusions:SE have more difficulty to discriminate and to integrate sensory information than AE and YA indicating that physical activity may improve sensory integration. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to investigate the adaptive process in the coupling between visual information and body sway in children postural control. Twenty-seven children from 4-, 8- and 12-year-olds and ten adults stood upright inside of a moving room. In the first 2min, the room was moved continuously at frequency of 0.2Hz, velocity of 0.6cm/s and amplitude of 0.5cm. In the minute subsequent the room was moved with velocity of 3.5 and amplitude of 3.2 and in the last 2min with velocity of 0.6cm/s and amplitude of 0.5cm. Gain, phase, SFSA and transient gain were used to examine the relationship between sensory information and body sway. The results showed that children and adults were capable to adapt to the changes of visual stimulus, downweighting the visual information influences when the room''s amplitude/velocity increased. However, the young children did not show calibrated response to the 12-year-old children and adults level, being more influenced by the visual stimulus. [Copyright &y& Elsevier]

Abstract: The literature shows conflicting results regarding older adults’ (OA) postural control performance. Differing task demands amongst scientific studies may contribute to such ambiguous results. Therefore, the purpose of this study was to examine the performance of postural control in older adults and the relationship between visual information and body sway as a function of task demands. Old and young adults (YA) maintained an upright stance on different bases of support (normal, tandem and reduced), both with and without vision, and both with and without room movement. In the more demanding tasks, the older adults displayed greater body sway than the younger adults and older adults were more influenced by the manipulation of the visual information due to the room movement. However, in the normal support condition, the influence of the moving room was similar for the two groups. These results suggest that task demand is an important aspect to consider when examining postural control in older adults. [Copyright &y& Elsevier]