Postural Control In Healthy Subjects Research Articles

Spinal articulation exercise using an exercise ball enhances dynamic postural control

PurposeWe hypothesized that exercises that selectively utilize local muscles responsible for segmental movements of the spine might promote local muscle activity and dynamic postural balance. In this study, we examined the effects of selective local muscle exercises (spinal articulation exercise) on dynamic postural control in healthy subjects. MethodsThe effects of spinal articulation exercise were examined using a deflated exercise ball for the postural sway in healthy students who were assigned to an exercise or control group. The independent variable was the extent of exposure to selective local muscle exercise, and the dependent variable was dynamic postural control. A stabilometer, which measures dynamic postural control, was used to evaluate the effectiveness of the exercises. In addition, center of gravity movements were assessed using a Gravicorder G-620 stabilometer in which the subject was asked to shift their center of gravity between 2 circles on a computer monitor. Pre- and post-intervention dynamic postural control was statistically evaluated between the exercise group and control group using the Mann-Whitney test. ResultsThe post-intervention average COUNTS were significantly higher in the exercise group than in the control group (p = 0.003, r = 0.78). ENV. AREA was significantly smaller in the exercise group than in the control group (p = 0.036, r = 0.54). Furthermore, LNG/COUNTS were significantly smaller in the exercise group than in the control group (p = 0.024, r = 0.58). ConclusionsSpinal articulation exercise may be used to enhance the dynamic postural balance of healthy young adults.

Posture of Healthy Subjects Modulated by Transcutaneous Spinal Cord Stimulation.

Transcutaneous electrical stimulation of the spinal cord is used to restore locomotion and body weight support in patients with severe motor disorders. We studied the effects of this non-invasive stimulation on postural control in healthy subjects. Stimulation at the L1-L2 vertebrae was performed to activate the extensor muscles of the lower limbs. Because postural regulation depends on the cognitive style, the effects of the stimulation were analyzed separately in field-dependent (FD) and field-independent (FI) participants. During the study, FD and FI participants (N = 16, 25 ± 5 years, all right dominant leg) stood on a force platform in a soundproof chamber with their eyes closed. Stimulation was applied in the midline between the L1 and L2 vertebrae or over the left or right dorsal roots of the spinal cord; under the control condition, there was no stimulation. Stimulation destabilized posture in healthy subjects, whereas patients with movement disorders usually showed an improvement in postural control. In the FD participants, left dorsal root and midline stimulation increased several postural parameters by up to 30%. Dorsal root stimulation on the side of the supporting leg reduced postural control, while stimulation on the side of the dominant leg did not. No significant changes were observed in the FI participants.

Load-Induced Changes of Inter-Limb Asymmetries in Dynamic Postural Control in Healthy Subjects.

Inter-limb asymmetries are associated with a higher potential risk for non-contact injuries. Differences in function or performance between the limbs might lead to imbalances and promote instability, increasing the potential risk for injuries. Consequently, an investigation of inter-limb asymmetries should be included in injury risk assessment. Furthermore, since non-contact injuries mainly occur under loaded conditions, an investigation of load-induced changes of inter-limb asymmetries can provide additional information on the athlete’s potential injury risk. Therefore, the current study aimed to investigate the influence of physical load on inter-limb asymmetries in dynamic postural control, which is essential in situations with a high risk for non-contact injuries such as landing, cutting, or stopping. In total, dynamic postural control of 128 active and healthy subjects (64 males and 64 females, age: 23.64 ± 2.44, height: 176.54 ± 8.96 cm, weight: 68.85 ± 10.98 kg) was examined. Dynamic postural control was tested with the Y-Balance Test (YBT) before and after a loading protocol on a bicycle ergometer or a treadmill. The results showed no significant increase of the inter-limb asymmetries in anterior direction [F(1, 126) = 4.44, p = 0.04, η2p = 0.03]. Moreover, there is high variation between the subjects regarding the magnitude and the direction of the asymmetries and the changes due to load. Therefore, a more individual analysis considering the magnitude and the direction of the asymmetries is required. Thereby, considering different modifying factors, e.g., sex, injury history, and baseline level of asymmetries, can be helpful. Moreover, an analysis of the changes during load might provide further insights, reveal possible differences, and help detect the reasons and mechanisms underlying inter-limb asymmetries and asymmetrical loading.

Overload of anxiety on postural control impairments in chronic stroke survivors: The role of external focus and cognitive task on the automaticity of postural control.

BackgroundDespite the high prevalence of anxiety among chronic stroke survivors and evidence of its negative effects on postural control in healthy subjects, it is unclear whether anxiety also affects postural control in these patients. Recent evidence of improved postural control of healthy subjects by distracting the attention using an external focus (EF) or cognitive task, raises the question of whether similar benefits would be observed in stroke survivors. Thus, the current study aimed to investigate the effects of anxiety and distracting the attention on postural control of chronic stroke survivors in terms of both postural sway measures and neuromuscular regulation.MethodsPostural sway measures and ankle muscle activity of chronic stroke survivors with the high and low level of anxiety (HA-stroke (n = 17), and LA-stroke (n = 17), respectively) and age-, sex-, height-, and weight-matched healthy subjects (n = 17) were assessed while standing on rigid and foam surfaces under following conditions: baseline, internal focus (IF), EF, simple and hard cognitive tasks (SC and HC, respectively).ResultsStroke survivors, particularly HA-stroke participants, showed greater postural sway measures (i.e. postural instability) and enhanced co-contraction of ankle muscles (i.e. stiffening of the neuromuscular system) compared with healthy subjects. As opposed to baseline and IF conditions, postural instability and neuromuscular stiffening significantly reduced in EF condition and decreased more in cognitive task conditions, particularly HC condition.ConclusionsThe results suggest that anxiety enhances stroke-induced postural instability promoting improper neuromuscular control of posture with stiffening strategy, which can be alleviated by EF and cognitive tasks.

Can action observation modulate balance performance in healthy subjects?

BackgroundAction observation activates brain motor networks and, if followed by action imitation, it facilitates motor learning and functional recovery in patients with both neurological and musculoskeletal disorders. To date, few studies suggested that action observation plus imitation can improve balance skills; however, it is still unclear whether the simple repetitive observation of challenging balance tasks is enough to modify postural control. Thus, the primary aim of this study was to investigate whether repetitive action observation of balance exercises without imitation has the potential to improve balance performance; the secondary aim was to estimate the different training effects of action observation, action observation plus imitation and balance training relative to a control condition in healthy subjects.MethodsSeventy-nine healthy young adults were randomly assigned to 4 groups: action observation, action observation plus imitation, balance training and control. The first three groups were trained for about 30 minutes every day for three weeks, whereas the control group received no training. Center of pressure path length and sway area were evaluated on a force platform at baseline and after training using posturographic tests with eyes open and closed.ResultsAs expected, both action observation plus imitation and balance training groups compared to the control group showed balance improvements, with a medium to large effect size performing balance tasks with eyes open. Action observation without imitation group showed a balance improvement with eyes open, but without a significant difference relative to the control group.ConclusionsBoth action observation plus imitation and balance training have similar effects in improving postural control in healthy young subjects. Future studies on patients with postural instability are necessary to clarify whether AOT can induce longer lasting effects. Action observation alone showed a trend toward improving postural control in healthy subjects, suggesting the possibility to study its effects in temporarily immobilized diseased subjects.

Effects of nanotechnology-based devices on postural control in healthy subjects.

The aim of the present preliminary randomized controlled study was to ascertain whether the use of newly developed nanotechnologies-based patches can influence posture control of healthy subjects. Thirty healthy female subjects (age 39.4 years, BMI 22.74 kg/m2) were randomly assigned to two groups: one with active patches and a control group with sham patches. Two patches were applied with a tape: one on the subject's sternum and the other on the C7 apophysis. Body sway during quiet upright stance was recorded with a dynamometric platform. Each subject was tested under two visual conditions, eyes open and closed. We used a blocked stratified randomization procedure conducted by a third party. Subjects wearing the sham patches showed a significant increase of the center of pressure sway area after 4 hours when they performed the habitual moderate-intensity work activities. In the active patch group, a decrease of the sway path was evident, providing evidence of an enhanced balance control. Our preliminary findings on healthy subjects indicate that nanotechnological devices generating ultra-low electromagnetic fields can improve posture control.

神経リハビリテーションにおける近赤外分光法の応用

Functional Near-Infrared Spectroscopy (fNIRS) is a characteristically functional neuroimaging technique which enables us to measure the daily tasks related to cortical activation including gait and postural task. Using fNIRS, it was found that the medial sensorimotor and supplementary motor area play an important role in gait and postural control in healthy subjects. In addition, it was also revealed that the individual balance ability was correlated with the cortical activation in the supplementary motor area during the postural task. These findings supported the notion that the supplementary motor area is one of the key structures for balance recovery in stroke patients. Not only can fNIRS effectively monitor the functional reorganization of the central nervous system, but fNIRS has also been used as a therapeutic tool. With recent advances in technique enabling real-time decoding of brain activity, functional neuroimaging can now be used as a neurofeedback tool, in which the voluntary modulation of cortical activation is available. After we developed a working fNIRS mediated neurofeedback system and confirmed its neuromodulation effect in healthy subjects, we investigated its clinical efficacy as a therapeutic tool for augmenting the functional recovery after stroke. Our pilot randomized control study revealed the promising result that neurofeedback intervention could improve finger function in chronic stroke patients including patients with moderate to severe paresis. These findings provide a new therapeutic possibility for those patients who gain only limited functional recovery from conventional rehabilitative interventions in the chronic stage.

Talocrural Joint Mobilization's Lack of Effect on Postural Control in Healthy Subjects

Talocrural Joint Mobilization's Lack of Effect on Postural Control in Healthy Subjects

The effect of a simulated knee joint effusion on postural control in healthy subjects

Palmieri RM, Ingersoll CD, Cordova ML, Kinzey SJ, Stone MB, Krause BA. The effect of a simulated knee joint effusion on postural control in healthy subjects. Arch Phys Med Rehabil 2003;84:1076-9. Objective:To determine the effects of a simulated knee joint effusion on center of pressure (COP) path and mean power frequency (MPF) during standing. Design:Quasi-experimental design. Setting:Sports injury research laboratory in a university setting. Participants:Twenty healthy volunteers, 10 of whom (age, 20.1±2.4y; height, 168.0±8.1cm; weight, 70.4±13.3kg) were assigned to an effusion group and 10 of whom (age, 25±3.8y; height, 169.4±8.9cm; weight, 74.7±7.7kg) were assigned to a control group. Interventions:COP data were collected before and after a 60-mL injection of sterile saline into the knee joint space. Main Outcome Measures:COP path and mediolateral and anteroposterior MPF. Results:COP path decreased after the effusion (pre-effusion mean, 92.2±21.9cm; posteffusion mean, 77.27±23.0cm). No change was found within the control group for COP path (P>.05). No differences were detected before or after joint effusion when the MPF was examined (P>.05). Conclusions:Possible explanations for the improved postural control after the effusion include additional somatosensory feedback, an augmented neural drive to the soleus, and/or increased capsular tension.

Effect of Rear-Foot Orthotics on Postural Control in Healthy Subjects

Objective:To identify changes in sagittal- and frontal-plane center of pressure (COP) excursion length and velocity during single-leg stance under 6 orthotic conditions.Design:1 × 6 repeated-measures.Setting:University biomechanics laboratory.Participants:Fifteen healthy young adults without excessive forefoot, arch, or rear-foot malalignments.Measurements:Selected variables of COP length and velocity were calculated in both the frontal and sagittal planes during three 5-second trials of quiet unilateral stance.Methods:Postural control was assessed under 6 conditions: shoe only and 5 orthotics.Results:The medially posted orthotic caused the least frontal COP length and velocity, and the Cramer Sprained Ankle Orthotic® caused the greatest frontal-plane sway. No significant differences were found between the different orthotic conditions in sagittal-plane measures.Conclusions:Differently posted rear-foot orthotics had various effects on frontal-plane postural control in healthy participants. Further research is needed on pathological populations.

Organizing Sensory Information for Postural Control in Altered Sensory Environments

Healthy human subjects can maintain adequate balance despite distorted somatosensory or visual feedback or vestibular feedback distorted by a peripheral vestibular disorder. Although it is not precisely known how this sensorimotor integration task is achieved, the nervous system coordinates information from multiple sensory systems to produce motor commands differently in different sensory environments. These different ways of coordinating sensory information and motor commands can be thought of as “sensorimotor states”. The way the nervous system distributes the monitoring of postural sway among states is analysed in this paper as a logical structure of transitions between states. The form of the transition structure is specified and distinguished from a finite state machine. The hypothesis that the nervous system could use a transition structure to maintain balance is tested by developing transition structures which are consistent with a set of experimental observations of postural control in healthy subjects and three groups of patients with peripheral vestibular disease.