Is there a relationship between complaints of impaired balance and postural control disorder in community-dwelling elderly women? A cross-sectional study with the use of posturography

Age-Related Differences in Intermuscular Coherence EMG-EMG of Ankle Joint Antagonist Muscle Activity during Maximal Leaning

BACKGROUND

Intermuscular synchronization is one of the fundamental aspects of maintaining a stable posture and is of great importance in the aging process. This study aimed to assess muscle synchronization and postural stabilizer asymmetry during quiet standing and the limits of stability using wavelet analysis. Intermuscular synchrony and antagonistic sEMG-sEMG (surface electromyography) coherence asymmetry were evaluated in the tibialis anterior and soleus muscles.

METHODS

The study involved 20 elderly (aged 65 ± 3.6) and 20 young (aged 21 ± 1.3) subjects. The task was to perform a maximum forward bend in a standing position. The prone test was divided into three phases: quiet standing (10 s), dynamic learning, and maintenance of maximum leaning (20 s). Wavelet analysis of coherence was performed in the delta and beta bands.

RESULTS

Young subjects modulated interface coherences to a greater extent in the beta band. Analysis of postural stability during standing tasks showed that only the parameter R2b (the distance between the maximal and minimal position central of pressure), as an indicator for assessing the practical limits of stability, was found to be significantly associated with differences in aging.

CONCLUSION

The results showed differences in the beta and delta band oscillations between young and older subjects in a postural task involving standing quietly and leaning forward.

Diagnostic Accuracy of Clinical Tests for the Indirect Assessment of Hip Abductor Muscle Strength in Community-Dwelling Older Women

OBJECTIVE

The objective of this study was to determine the accuracy of 3 clinical tests (lateral step [LS], tandem gait [TG], and single-leg stance [SS]) in identifying older women with reduced hip abductor muscle strength and to determine the post-test probability of each test and of their combination in changing the certainty of diagnosis.

METHODS

In this cross-sectional study, a total of 123 older women received clinical testing to obtain the variables LS height, time for TG execution, percentage of errors in TG, and time of permanence on SS and were tested for isometric hip abductor peak torque using an isokinetic dynamometer. Only the dominant lower limb was evaluated. Multiple linear regression analysis with adjustment was performed to determine the association among variables, followed by the receiver operating characteristic curve to identify clinical variables that can discriminate older women with reduced abductor muscle strength. Post-test probability was then calculated based on the receiver operating characteristic curve data.

RESULTS

Although the 4 clinical variables showed correlation with abductor peak torque, only LS and TG time were able to discriminate reduced abductor muscle strength with low accuracy (area under the curve was between 0.5 and 0.7). However, the combination of LS and TG time increased post-test probability from 47% (prevalence of weakness in the population) to 76% when both tests were positive and reduced it from 47% to 18% when both tests were negative.

CONCLUSION

The combination of the LS test and TG time is useful for the indirect assessment of hip abductor strength in community-dwelling older women.

IMPACT

Hip abductor muscle strength is extremely important for function in older women. This study presents clinicians with simple, fast, and inexpensive methods for assessing hip abductor muscle strength.

Accuracy of the step test to evaluate lower limb muscle strength in community-dwelling older women

OBJECTIVE

to investigate the accuracy of the step test (ST) to evaluate total lower limb muscle strength (LLMS) in older women.

DESIGN

observational cross-sectional study.

METHODS

119 community-dwelling older women were submitted to the ST and LLMS evaluation (isometric peak torque of eight muscle groups of the dominant lower limb). The capacity of the ST to discriminate older women with reduced LLMS was measured using ROC curve, followed by the posttest probability (PoTP) calculation.

RESULTS

a ST score of 0.24 cm per cm of participant's height presents a sensitivity of 63.3%, specificity of 77%; enhances the PoTP from 48% to 72% for positive test and decreases the PoTP from 48% to 31% for negative test.

CONCLUSION

the ST may complement the clinical screening of reduced LLMS in older women, given that it is a simple and quick low-cost test and allows the evaluation of each lower limb separately.

The effect of unilateral muscle fatigue of hip abductor muscles on balance and functional capacity in community-dwelling older women

BACKGROUND

Hip abductor muscles are important for the maintenance of postural stability, mainly on the mediolateral direction and unipodal support conditions. The objective of the present study was to evaluate the effect of unilateral induced fatigue of hip abductor muscles on balance and functional capacity of older women.

METHODS

The study included physically independent women aged 60-75 years. We assessed static balance with the single limb stance test (SLS) and evaluated functional capacity with the maximum gait speed (MGS) and step test (ST). We ran the protocol of hip abductor muscle fatigue with a Biodex isokinetic dynamometer. Assessment of balance and functional capacity happened before and after the muscle fatigue protocol. We applied the t-test for repeated measures to determine whether unilateral hip abductor muscle fatigue influences the performance in the tests (SLS, MGS and ST).

RESULTS

The protocol of hip abductor muscle fatigue negatively affected all three evaluated tasks: SLS (p = 0.000), ST (p = 0.000) and MGS (p = 0.000). However, the single limb stance test was the most task affected (effect size = 0.51, pre- and post-fatigue difference = 28.1 %).

CONCLUSION

After the unilateral muscle fatigue of hip abductors, we observed the worst performance on clinical tests, mainly regarding the SLS test, which shows the involvement of hip abductors during usual motor tasks. However, the small magnitude of the limitation of functional tests (MGS and ST) suggests the presence of postural compensations.

Risk factors for future falls among community-dwelling older adults without a fall in the previous year: A prospective one-year longitudinal study

INTRODUCTION

One of the main risk factor for falls is a history of falls itself. Henceforth, preventing a fall is an important strategy for the prevention of new ones. The objective of the present study was to determine whether personal self-perception questions and functional tests might represent risk factors for a fall during the year following a year without any falls among independent community-dwelling older adults, considering a period of 12 prospective months.

METHODS

A total of 101 community-dwelling older adults without a fall in the previous year underwent an initial evaluation (sample characterization, self-perception questionnaire and functional tests) and monthly monitoring of prospective fall episodes by telephone contact. We determined the association between the occurrence of prospective falls (dependent variable) and personal questions and functional tests (independent variables) with multiple binary logistic regression adjusted for confounding variables.

RESULTS

Only age (p = 0.005) and self-perception of general health (p = 0.019) showed association with the occurrence of prospective falls.

CONCLUSION

Our results showed that the only factors bearing an association with the occurrence of prospective falls were age and general health self-perception, which demonstrates the importance of administrating self-perception measures in clinical practice or in epidemiological studies for the prevention of a fall during the year following a year without any falls in older adults.

Analysis of Ankle sEMG on Both Stable and Unstable Surfaces for Elderly and Young Women-A Pilot Study

Body aging is frequently accompanied with numerous consequences such as increased tendency to falls, which may be connected not only with the impaired ability of keeping balance, but also with some limitations of the system responsible for the maintenance of balance. The aim of this study was defining the importance of muscle activity in the ankle joint when standing on stable and unstable surfaces with eyes open and closed as well as examining indications of the influence of body aging on the activity of the selected muscles. The study was carried out on a group of 20 healthy women divided into two age groups (aged 24 ± 3.6 years and aged 64 ± 4.2 years). The activity of muscles stabilizing the ankle joint while standing on different types of surfaces was tested with an EMG (surface electromyography) on both elderly and young women during trials with open and closed eyes. The tests showed higher activation in the evaluated muscles of the anterior group (tibialis anterior (TA), peroneus longus (PL)) of elderly women. For the posterior shin muscles of both groups, a higher activation was observed in the gastrocnemius lateralis muscle (GL) of elderly women, whereas gastrocnemius medialis muscle (GM) showed highly comparable activity. The results obtained in this work confirm the importance of proprioception training and muscle strength in the rehabilitation of older people as well as in prophylactic exercise aimed toward the prevention of ankle injuries.

Community-dwelling adults with a history of falling report lower perceived postural stability during a foam eyes closed test than non-fallers

Perceived postural stability has been reported to decrease as sway area increases on firm surfaces. However, changes in perceived stability under increasingly challenging conditions (e.g., removal of sensory inputs) and the relationship with sway area are not well characterized. Moreover, whether perceived stability varies as a function of age or history of falls is unknown. Here we investigate how perceived postural stability is related to sway area and whether this relationship varies as a function of age and fall history while vision and proprioceptive information are manipulated. Sway area was measured in 427 participants from the Baltimore Longitudinal Study of Aging while standing with eyes open and eyes closed on the floor and a foam cushion. Participants rated their stability [0 (completely unstable) to 10 (completely stable)] after each condition, and reported whether they had fallen in the past year. Perceived stability was negatively associated with sway area (cm²) such that individuals who swayed more felt less stable across all conditions (β = - 0.53, p < 0.001). Perceived stability decreased with increasing age (β = - 0.019, p < 0.001), independent of sway area. Fallers had a greater decline in perceived stability across conditions (F = 2.76, p = 0.042) compared to non-fallers, independent of sway area. Perceived postural stability declined as sway area increased during a multisensory balance test. A history of falling negatively impacts perceived postural stability when vision and proprioception are simultaneously challenged. Perceived postural stability may provide additional information useful for identifying individuals at risk of falls.

One-legged stance sway of older adults with and without falls

Postural instability is a common problem among older people, and it is associated with mobility impairments, activity limitation and fear of falling. The evaluation of postural control can contribute to the early detection of balance deficits and help health professionals to manage this problem to prevent falls in older adults. The aim of this study was to identify center of pressure cut-offs to differentiate between older adults with and without falls in the past 12 months. The participants were 170 older adults (mean age 67 years, 50 fallers and 120 non-fallers). Center of pressure area and sway velocity in the anterior-posterior and medio-lateral directions were assessed using a force platform during three 30s one-legged stance trials with eyes open. The mean across trials was used for analysis. The time-limit (how long the participant was able to stay in one-legged stance, up to 30s) was also assessed. Fallers had poorer postural control than non-fallers (effect size ≥ 0.52, P <0.05). The cut-offs identified were 10.3 cm² for Center of pressure area, 2.9 cm/s for velocity in the anterior-posterior, and 3.4 cm/s for medio-lateral velocity. The force platform parameters obtained an area under the curve of 0.72, with sensitivity of 78% and specificity of 68%. There were no significant differences between non-fallers and fallers for time-limit variable (17 seconds vs. 18 seconds). Force platform parameters during one-legged stance were associated with history of falls in older adults. The cut-offs obtained acceptable area under curve, sensitivity and specificity, with center of pressure area presenting the best performance to differentiate between fallers and non-fallers.

Fatores associados às alterações de equilíbrio em idosos residentes no município de São Paulo em 2006: evidências do Estudo Saúde, Bem-Estar e Envelhecimento (SABE)

RESUMO: Objetivo: O objetivo deste estudo foi investigar a influência dos fatores demográficos, de condições de saúde e de estilo de vida nas alterações do equilíbrio corporal dos idosos residentes no município de São Paulo em 2006. Métodos: O estudo foi desenvolvido com base em dados provenientes do Estudo Saúde,Bem-Estar e Envelhecimento (SABE). Foram selecionados todos os indivíduos com 60 anos e mais de idade, de ambos os sexos. A amostra considerada era de 1.226 indivíduos, representando 930.639 idosos. A variável dependente foi a alteração de equilíbrio corporal do idoso. Para mensurá-la utilizou-se parte do Short Physical Performance Battery (SPPB). As variáveis independentes foram classificadas em três grupos: demográficas, de condições de saúde e de estilo de vida. Para estimar a associação entre as alterações de equilíbrio com as variáveis demográficas, de saúde e de estilo de vida em idosos foi realizada uma análise de regressão logística binária múltipla. Resultados: Idade, dificuldades em pelo menos uma mobilidade e realização de atividade física regular exercem uma significativa influência no equilíbrio corporal dos idosos (p < 0,05). A idade foi o determinante mais fortemente relacionado. Ter idade entre 75 a 79 anos e 80 anos e mais aumenta em 3,77 e 5,31vezes a chance, respectivamente, de os idosos apresentarem alterações de equilíbrio em comparação às idades de 60 a 64 anos. Conclusão: Medidas preventivas e que visam reverter um quadro de instabilidade corporal devem ser preconizadas e incorporadas na agenda de atenção à saúde dos idosos.