Impairments In Balance Control Research Articles

Regulation of whole-body frontal plane balance varies within a step during unperturbed walking

This study sought to determine whether the need to actively control lateral balance is consistent within a step. Variability of the frontal plane COM-Ankle angle was calculated over 50 strides at discrete gait events for twenty-one healthy young adults to quantify active control of lateral balance within a step. Frontal plane COM-Ankle angle variability was found to vary significantly between all gait events, decreasing progressively within a step. This suggests that active control of lateral balance varies significantly within a step and that the greatest degree of active control occurs at heel-strike. The increased active control of lateral balance during heel-strike indicates a degree of preparation to ensure sufficient lateral balance control prior to more challenging events. These results provide insight into the mechanisms of lateral balance control and how to assess and treat locomotor balance control impairments.

Unraveling the Association Between SSRI Use and Falls

Selective serotonin reuptake inhibitors (SSRIs) are widely used to treat depression and are also associated with an increased falls risk. However, the biological mechanism underlying accidental falls with SSRI intake has yet to be elucidated. The present experimental study was designed to investigate whether obstacle avoidance skills in long-term (>90 days), senior paroxetine users (61 ± 5.8 years) are affected during gait, simple and challenging postural balance tasks, as well as during manual reaction time tasks. The performance of the paroxetine users was compared with healthy group-matched controls (60 ± 4.8 years). The results demonstrated impaired postural balance in the paroxetine users, especially during one-legged stance or under various dual-task conditions. Although the deficit in one-legged stance could indicate vestibular involvement, this was deemed unlikely because performance of standing on compliant surface with closed eyes remained unaffected. Paroxetine use also failed to affect manual reaction times or obstacle avoidance performance. It is suggested that paroxetine affects attentional capacities particularly in conjunction with balance control. Compared with healthy seniors, long-term senior users of paroxetine seem to be at an increased risk of falling due to impairments in balance control, especially when attention has to be divided between 2 concurrent activities.

F15 Balance control in Huntington's disease: is the berg balance scale a useful test for clinical and quantitative motor assessment?

BackgroundPatients with Huntington's disease (HD) develop a progressive impairment of stability of stance and walking (Rumpf et al. 2007), frequently resulting in falls and injuries. Objective assessment of postural control...

The Effectiveness of Active Exercise as an Intervention for Functional Ankle Instability

Functional ankle instability (FAI) is a term used to describe an ankle that easily 'gives way' with activity. There have been many proposed causes of FAI including joint proprioceptive deficiency, muscle weakness, balance control impairments, and delayed muscle reaction time, none of which has proven to be the exclusive cause of FAI. Treatment becomes difficult when the causative factor of the injury is obscure. This systematic review evaluates the clinical trials involving conservative exercise interventions in FAI and examines the changes induced by the exercise treatments to the various potential FAI factors. Sixteen articles describing the active exercise treatment of FAI were analysed using Sackett's levels of evidence and were examined for scientific rigor. From this review, it can be concluded that conservative treatment interventions including balance, proprioceptive and muscle strengthening exercises are effective for patients with FAI in decreasing the incidence of giving-way episodes, improving balance stability, and improving function.

Enhancing Human Balance Control by Apply Random Vibrations to the Ankle Tendons

Somatosensory function declines with age, and such changes have been associated with postural instability. Recently, it has been shown that input noise can enhance sensory and motor function. PURPOSE: The goal of this study was to investigate whether subsensory mechanical noise applied to the ankles via randomly vibrating wraps can be used to improve balance control in young and elderly subjects. METHODS: Two quiet standing experiments were performed. Experiment 1 investigated the application of four different amplitudes of noise to find the noise level that produced the largest reduction in postural sway in twelve healthy young subjects. Experiment 2 tested further the effect of this optimal noise level on balance control in a sample of fifteen healthy young and fifteen healthy elderly subjects. To characterize balance during quiet standing, five traditional sway parameters, five sway parameters that have been shown to be predictive of falls, and three random-walk sway parameters were computed for the noise and control (no noise) trials, respectively, for each subject. RESULTS: In Experiment 1, four of the five traditional sway parameters indicated that the optimal level of mechanical noise was 75% of the sensory threshold for the subjects tested. In Experiment 2, application of this optimal level of noise (75% of sensory threshold) resulted in a reduction in 12 of the 13 sway parameters in the young subjects and all of the sway parameters in the elderly subjects. For the main effect of stimulation, decreases in 10 of the sway parameters– five traditional, three fall-predictive, and two random-walk parameters-were statistically significant (p <0.05). The elderly subjects also showed greater improvements than the young in the anteroposterior range of sway (p= 0.047). CONCLUSION: These findings suggest that noise-based devices, such as randomly vibrating ankle wraps, could ameliorate age-related impairments in balance control. Supported by NIH Grant HD37880, AG08812 andHD40035.

Noise‐enhanced balance control in patients with diabetes and patients with stroke

Somatosensory function declines with diabetic neuropathy and often with stroke, resulting in diminished motor performance. Recently, it has been shown that input noise can enhance human sensorimotor function. The goal of this study was to investigate whether subsensory mechanical noise applied to the soles of the feet via vibrating insoles can be used to improve quiet-standing balance control in 15 patients with diabetic neuropathy and 15 patients with stroke. Sway data of 12 healthy elderly subjects from a previous study on vibrating insoles were added for comparison. Five traditional sway parameters and three sway parameters from random-walk analysis were computed for each trial (no noise or noise). Application of noise resulted in a statistically significant reduction in each of the eight sway parameters in the subjects with diabetic neuropathy, the subjects with stroke, and the elderly subjects. We also found that higher levels of baseline postural sway in sensory-impaired individuals was correlated with greater improvements in balance control with input noise. This work indicates that noise-based devices could ameliorate diabetic and stroke impairments in balance control.

Postural balance and health-related factors in middle-aged and older women with injurious falls and non-fallers.

Older fallers aged over 70 years have shown impaired balance abilities, but it is unclear if impairment in balance control can be detected among fallers who are in their 50's and 60's. The aim of this study was to analyze possible differences in balance control and other health-related factors between female fallers and non-fallers aged 50-68 years. Women 50-68 years of age (N=40) who had fallen outside and needed medical attention were recruited through a larger fall accident study. Non-fallers (N=97) were women representing the same age group who had not fallen during the preceding 12 months. A battery of standing force platform balance tests were administered together with an interview on health status, use of medication, dizziness, vision, hearing, and physical activity. Significant differences were not found between women with injurious falls and non-fallers in the various balance tests. In the younger age group (50-58 years), chronic illnesses, use of medication, dizziness, and self-reported problems with vision and hearing were more common in fallers than in non-fallers. Our results suggest that, in active and independent women aged 50-68 years, it is not possible to use standing force platform balance tests to detect differences between fallers and non-fallers. However, younger women (50-58 years) with injurious falls reported more health-related problems than other groups, a fact which should be taken into consideration to prevent further development of fall-related problems.

Vibrating insoles and balance control in elderly people

Somatosensory function declines with age, and such changes have been associated with diminished motor performance. Input noise can enhance sensory and motor function. We asked young and elderly participants to stand quietly on vibrating gel-based insoles, and calculated sway parameters and random-walk variables. In our 27 participants, application of noise resulted in a reduction in seven of eight sway parameters in young participants and all of the sway variables in elderly participants. Elderly participants showed greater improvement than young people in two variables, mediolateral range (p=0.008), and critical mean square displacement (p=0.012). Noise-based devices, such as randomly vibrating insoles, could ameliorate age-related impairments in balance control.

Neural factors underlying reduced postural adaptability in children with cerebral palsy.

This study aimed to test mechanisms underlying impairments in balance control in children with cerebral palsy. We hypothesized that balance loss during large/fast perturbations could be due to reduced contraction of agonist muscles, delay in muscle contraction or simultaneous contraction of antagonist muscles, reducing the efficiency of the agonist burst. Electromyograms were recorded as children recovered from balance threats of varying magnitudes/velocities. In typically developing children muscle response magnitudes increased with larger/faster perturbations, while in children with cerebral palsy they did not. There was no difference in muscle onset latency or antagonist co-contraction between groups. Thus the primary constraint on balance recovery in these children is insufficient levels of contraction of agonist postural muscles.

Response preparation and posture control. Neuromuscular changes in the older adult.

Experiments comparing the characteristics of neuromuscular responses underlying balance control in young and old adults have shown a number of differences between the two populations. Postural muscle response latencies of the ankle musculature activated by external threats to balance are slightly, but significantly, longer in the latter population. In addition, some aging subjects show a temporal reversal of proximal and distal muscle response onset in some trials. There is also a breakdown of the correlation of the amplitude of the muscle responses within a synergy in some of the older subjects tested. Older adults also exhibited cocontraction of agonist and antagonist muscles within a response synergy to a greater extent than young adults. This stiffening of the joints by antagonist cocontraction could be a compensation for the lack of the ability to fine-tune the postural responses to the same degree as the young adults. Analysis of sensory integration abilities showed an impairment in balance control under conditions of reduced or conflicting sensory information. When they were given inappropriate visual and somatosensory inputs, half of the older adults lost balance on the first trial. In most instances, however, the older adults were able to maintain balance during a second trial consisting of the same sensory stimuli. When visual cues were reduced by restricting the visual field to either central or peripheral visual cues, we found no difference in postural muscle response latencies. However, the aging adult group showed more losses of balance than the younger group with peripheral vision removed or with eyes closed. In addition, there was a strong correlation between the subjects that showed stronger deficits on an initial neurological exam and the number of times that balance was lost. Studies on changes in the linkage between postural and voluntary muscle interactions during voluntary arm movements in older adults indicate an increase in the latency of feed-forward activation of postural muscles. However, voluntary muscle response onset latencies show greater increases in the old compared to the young. This suggests that deterioration of the speed of activation of the postural control system is not the only factor that limits the speed of voluntary movement onset. Measurements have not yet been made on the amplitude regulation of feed-forward responses of postural muscles during a voluntary task. It may be that the regulation of the speed of activation of the two systems is less important than the fine tuning of the correlation of appropriate response amplitudes between the two systems.(ABSTRACT TRUNCATED AT 400 WORDS)