Swimming, better than tennis, develops sensorimotor adaptabilities involved in postural balance in 5-6-year-old children.

PURPOSE: The present study aimed to evaluate the postural balance of young tennis players and young swimming practitioners in static and dynamic conditions. METHODS: Thirty-six children (5-6 years old) participated in 3 groups: 12 tennis players, 12 swimming practitioners and 12 controls. Static and dynamic [in medial lateral (ML) and anterior posterior (AP) planes] postural balance were assessed by the centre of pressure sways using a stabilometric force platform in the eyes opened (EO) and eyes closed (EC) conditions. RESULTS: In the EO condition, swimming practitioners and tennis players had a significantly lower (p < 0.05) centre of pressure mean velocity (CoPVm) compared to controls in both static and dynamic medial-lateral (D-ML) postures. In the D-ML posture, swimming practitioners showed lower CoPVm compared to tennis players. However, in the EC condition, only the swimming practitioners showed better static and D-ML postural balance (p < 0.05) compared to their counterparts. In the static posture, the Romberg index value was significantly higher (p < 0.05) in tennis players compared to the two other groups. CONCLUSION: Tennis players developed a higher reliance on vision to maintain balance, whereas swimming practitioners were more stable in challenging postural conditions. Clinicians should consider incorporating swimming training rather than tennis as an appropriate balance training in fall-prevention programs.

Regular physical activity reduces the effects of Achilles tendon vibration on postural control for older women.

The aim was to determine in what extent physical activity influences postural control when visual, vestibular, and/or proprioceptive systems are disrupted. Two groups of healthy older women: an active group (74.0 ± 3.8 years) who practiced physical activities and a sedentary group (74.7 ± 6.3 years) who did not, underwent 12 postural conditions consisted in altering information emanating from sensory systems by means of sensory manipulations (i.e., eyes closed, cervical collar, tendon vibration, electromyostimulation, galvanic vestibular stimulation, foam surface). The center of foot pressure velocity was recorded on a force platform. Results indicate that the sensory manipulations altered postural control. The sedentary group was more disturbed than the active group by the use of tendon vibration. There was no clear difference between the two groups in the other conditions. This study suggests that the practice of physical activities is beneficial as a means of limiting the effects of tendon vibration on postural control through a better use of the not manipulated sensory systems and/or a more efficient reweighting to proprioceptive information from regions unaffected by the tendon vibration.

Pilates versus Zumba training effects on postural control under conflicting sensory conditions in postmenopausal women.

The current study aimed to compare the effects of Pilates versus Zumba training on postural performance in middle-aged postmenopausal women. Fifty-seven eligible women, aged between 50 and 60 years, were randomized into three groups: Zumba (ZG) group, Pilates (PG) group or control (CG) group. Postural control was assessed using a force platform under 4 sensory manipulation conditions: on firm and foam surfaces with eyes opened (EO) and closed (EC). Our results showed more marked adaptations in favor of ZG concerning postural performance compared to PG. For the PG, postural control was significantly improved only in simple postural conditions on the firm surface with EO (p < 0.1) and EC (p < 0.05) conditions. However, postural control of the ZG significantly improved in both the simple and complex postural conditions, even under conflicting sensory situations (firm surface/EO (p < 0.001; 95 % CI: [1.34, 4.46]), EC (p < 0.001; 95 % CI: [2.13, 5.24])); foam surface/EO (p < 0.01; 95 % CI: [0.70, 8.57]), EC (p < 0.01; 95 % CI: [0.65, 8.52])). In conclusion, Zumba training seems to be more effective and a better strategy to promote postural control in daily living activities and autonomy in postmenopausal women than Pilates training. These findings are useful for public health practitioners in designing physical interventions for balance disorders.

Focal clusters of peri-synaptic matrix contribute to activity-dependent plasticity and memory in mice.

Recent findings show that effective integration of novel information in the brain requires coordinated processes of homo- and heterosynaptic plasticity. In this work, we hypothesize that activity-dependent remodeling of the peri-synaptic extracellular matrix (ECM) contributes to these processes. We show that clusters of the peri-synaptic ECM, recognized by CS56 antibody, emerge in response to sensory stimuli, showing temporal and spatial coincidence with dendritic spine plasticity. Using CS56 co-immunoprecipitation of synaptosomal proteins, we identify several molecules involved in Ca2+ signaling, vesicle cycling, and AMPA-receptor exocytosis, thus suggesting a role in long-term potentiation (LTP). Finally, we show that, in the CA1 hippocampal region, the attenuation of CS56 glycoepitopes, through the depletion of versican as one of its main carriers, impairs LTP and object location memory in mice. These findings show that activity-dependent remodeling of the peri-synaptic ECM regulates the induction and consolidation of LTP, contributing to hippocampal-dependent memory.

Effects of Music Listening on Postural Balance in Adolescents with Visual Impairment.

We aimed to investigate the effect of music on visually impaired adolescents' postural balance across different somatosensory and vestibular input conditions. We recruited 19 adolescent participants (9 males, 10 females) with severe congenital visual impairment. We recorded their mean center of pressure velocity (CoPVm) during static upright bipedal standing under somatosensory (firm and foam surfaces) and vestibular (head facing forward (HFF), head rotated 90° to the right (HRR), and head rotated 90° to the left (HRL)) perturbations in three auditory conditions (no-music, listening to Jupiter, and listening to their preferred music). We found that CoPVm decreased significantly when listening to both Jupiter and preferred music, compared to the no-music condition on both firm (p < .05) and foam (p < .001) surfaces and with the HFF (p < .05), rotated to the right (p < .001) or rotated to the left (p < .001). Moreover, CoPVm values increased significantly with somatosensory manipulation (p < .001) in all the auditory conditions and with vestibular manipulation (p < .01) only in the no-music condition. We concluded that listening to both Jupiter and preferred music improved postural balance in visually impaired adolescents, even in challenged postural conditions.

Visual, Vestibular, and Proprioceptive Dependency of the Control of Posture in Chronic Neck Pain Patients.

Sensory reweighting of postural control was compared in participants with and without neck pain. Center of pressure variables of 60 volunteers, the same in each group, were calculated under four standing conditions: (a) eyes open, neutral head posture; (b) foam interface, eyes open; (c) cervical extension, eyes open; and (d) cervical extension, eyes closed. All center of pressure variables except anterior posterior range/velocity increased significantly in Condition 2 compared with Conditions 1 and 3 (p < .001) and in Condition 4 compared with Conditions 1 and 3. The mediolateral range/velocity and path length in both groups, anterior posterior range in patients, and center of pressure area in the control group were significantly different between Conditions 2 and 4 (p < .001). No overweighting was observed on the vestibular or visual afferents in patients. Compensatory strategies seem to lie within the proprioceptive system.

The tightening parameters of the vibratory devices modify their disturbing postural effects.

The purpose was to specify the impact of two different forces exerted by vibratory devices on the Achilles tendon on postural balance. The postural balance of 13 participants was evaluated on a force platform in two 40 s bipedal stance conditions with closed eyes. Tendon vibrations (80 Hz) were triggered 10 s after the beginning of the postural evaluation and applied during 20 s. Two levels of the force exerted by the vibrators were calibrated using load cells to control the tightening parameters of the vibrators: a strong tightening (ST) condition at 45 N and a light tightening (LT) condition at 5 N. The soleus electromyographic (EMG) activity and the spatio-temporal parameters of displacement of the centre of foot pressure (COP) were analysed. To analyse the effects of the introduction, the adaptation and the end of the stimulation, non-parametric tests were used. The results indicated that the soleus EMG activity increased only in the ST condition. However, during the vibration the anteroposterior COP position was significantly more in a backward position in the LT condition. At the end of the vibration, COP parameters increased more in the LT condition than the ST condition. This study demonstrated that the effects of the vibration depended on the force exerted by the devices on the tendons. The ST increased the vibration effects on EMG activity through greater stimulating effects compared to the LT. However, the ST could also increase the ankle joint stiffness and/or somaesthetic sensory information, which attenuated the COP backward shift.

Comparison of the reliance of the postural control system on the visual, vestibular and proprioceptive inputs in chronic low back pain patients and asymptomatic participants.

BACKGROUND: Although proprioception deficits have been documented in chronic low back pain (CLBP) patients, little is known about adaptive strategies to provide postural control in these patients. Substitution of unreliable proprioceptive information with other afferents might be considered plausible. RESEARCH QUESTION: Is the response of the postural control system dependent on the source of sensory afferents being manipulated in persons with and without CLBP? METHODS: Sixty persons with and without CLBP participated in this cross-sectional study. Center of pressure (COP) displacement range, velocity, path length and area were calculated under four sensory conditions: 1) normal upright standing; 2) upright standing on a foam with eyes open and head in neutral position; 3) upright standing with eyes open and 60° cervical extension and 4) upright standing with eyes closed and 60° cervical extension. A two-way repeated measures analysis of variance was used to compare COP masseurs under different conditions and between the groups. RESULTS: CLBP patients demonstrated fewer alterations to manipulation of both visual and vestibular afferents in terms of number of COP variables significantly altered. ML range and velocity in both groups and path length in the CLBP group were significantly different between conditions 2 and 4. In both groups, all COP variables except AP range increased significantly in condition 2 compared to conditions 1and 3 (p < 0.001). AP velocity was the only variable to be different between conditions 1 and 3 in both CLBP (p = 0.025) and control (p < 0.001) groups. Between group differences were significant on AP velocity (p = 0.019). SIGNIFICANCE: No overweighting was observed in the vestibular or visual afferents in CLBP patients. Compensatory strategies seem to lie within proprioceptive system by reweighting afferents from different body segments. The postural control system behaved more robustly in CLBP patients while AP COP velocity was found as the most sensitive and discriminating parameter.

Perception of postural verticality in roll and pitch while sitting and standing in healthy subjects.

Assessment of verticality perception is increasingly used in patients with disorders of upright body orientation, e.g. in pusher behavior after hemispheric stroke or in retropulsion in neurovascular or degenerative diseases. The subjective postural vertical (SPV) assesses the individual's perceived upright body orientation in space and can be determined in a sitting or a standing position. As somatosensory input differs between sitting and standing, we suppose a different representation of verticality. Thus, the aim of this study was to compare the SPV while sitting and while standing, and to determine the influence of proprioceptive and visual stimulations on the SPV in both positions. Twenty healthy subjects (18-40 years, 9 female) participated in two experiments. In experiment 1 the SPV was assessed in the pitch and roll planes while sitting and standing. In experiment 2 we additionally applied somatosensory Achilles tendon vibration and visual optokinetic stimulation. Results of experiment 1 revealed no difference of the SPV error between sitting and standing. Though, we found an increased SPV variability while sitting. Experiment 2 showed no effect of sensory manipulation in the pitch plane, but an effect of optokinetic stimulation in the roll plane. The tilt in direction of the visual stimuli was more pronounced while sitting. Optokinetic stimulation also resulted in a larger SPV variability in roll, indicating larger insecurity in verticality estimation during stimulation. In conclusion, even though the SPV assessment while sitting and standing resulted in similar mean values, the larger variability and the higher sensitivity to visual stimuli while sitting suggest different strategies for verticality estimation while sitting and while standing.

Right cerebral hemisphere specialization for quiet and perturbed body balance control: Evidence from unilateral stroke.

Our aim in this investigation was to assess the relative importance of each cerebral hemisphere in quiet and perturbed balance, based on uni-hemispheric lesions by stroke. We tested the hypothesis of right cerebral hemisphere specialization for balance control. Groups of damage either to the right (RHD, n=9) or the left (LHD, n=7) cerebral hemisphere were compared across tasks requiring quiet balance or body balance recovery following a mechanical perturbation, comparing them to age-matched nondisabled individuals (controls, n=24). They were evaluated in conditions of full and occluded vision. In Experiment 1, the groups were compared in the task of quiet standing on (A) rigid and (B) malleable surfaces, having as outcome measures center of pressure (CoP) amplitude and velocity sway. In Experiment 2, we evaluated the recovery of body balance following a perturbation inducing forward body oscillation, having as outcome measures CoP displacement, peak hip and ankle rotations and muscular activation of both legs. Results from Experiment 1 showed higher values of CoP sway velocity for RHD in comparison to LHD and controls in the anteroposterior (rigid surface) and mediolateral (malleable surface) directions, while LHD had lower balance stability than the controls only in the mediolateral direction when supported on the rigid surface. In Experiment 2 results showed that RHD led to increased values in comparison to LHD and controls for anteroposterior CoP displacement and velocity, time to CoP direction reversion, hip rotation, and magnitude of muscular activation in the paretic leg, while LHD was found to differ in comparison to controls in magnitude of muscular activation of the paretic leg and amplitude of mediolateral sway only. These results suggest that damage to the right as compared to the left cerebral hemisphere by stroke leads to poorer postural responses both in quiet and perturbed balance. That effect was not altered by manipulation of sensory information. Our findings suggest that the right cerebral hemisphere plays a more prominent role in efferent processes responsible for balance control.

Vestibular Adaptations Induced by Gentle Physical Activity Are Reduced Among Older Women.

The aim of this study was to compare the ability of older individuals to maintain an efficient upright stance in contexts of vestibular sensory manipulation, according to their physical activity status. Two groups of healthy older women (aged over 65) free from any disorders (i.e., neurological, motor and metabolic disorders) and vestibular disturbances, participated in this study. One group comprised participants who regularly practiced gentle physical activities, i.e., soft gym, aquarobic, active walking, ballroom dancing (active group, age: 73.4 (5.8) years, n = 17), and one group comprised participants who did not practice physical activities (non-active group, age: 73.7 (8.1) years, n = 17). The postural control of the two groups was compared in a bipedal reference condition with their eyes open and two vestibular sensory manipulation conditions (i.e., bipolar binaural galvanic vestibular stimulation (GVS) at 3 mA, in accordance with two designs). The main results indicate that there was no difference between the active and the non-active groups in all the conditions. It is likely that the aging process and the type of physical practice had limited the ability of the active group to counteract the effects of vestibular sensory manipulation on postural control more efficiently than the non-active group.

The effect of vision elimination during quiet stance tasks with different feet positions.

Literature confirms the effects of vision and stance on body sway and indicates possible interactions between the two. However, no attempts have been made to systematically compare the effect of vision on the different types of stance which are frequently used in clinical and research practice. The biomechanical changes that occur after changing shape and size of the support surface suggest possible sensory re-weighting might take place. The purpose of this study was to assess the effect of vision on body sway in relation to different stance configurations and width. Thirty-eight volunteers performed four quiet stance configurations (parallel, semi-tandem, tandem and single leg), repeating them with open and closed eyes. Traditional parameters, recurrence quantification analysis and sample entropy were analyzed from the CoP trajectory signal. Traditional and recurrence quantification analysis parameters were affected by vision removal and stance type. Exceptions were frequency of oscillation, entropy and trapping time. The most prominent effect of vision elimination on traditional parameters was observed for narrower stances. A significant interaction effect between vision removal and stance type was present for most of the parameters observed (p<0.05). The interaction effect between medio-lateral and antero-posterior traditional parameters differed in linearity between stances. The results confirm the effect of vision removal on the body sway. However, for the medio-lateral traditional parameters, the effects did not increase linearly with the change in width and stance type. This suggests that removal of vision could be more effectively compensated by other sensory systems in semi-tandem stance, tandem and single legged stance.