Reproducibility of dynamometers in handrail format in evaluating handgrip strength and traction in young and older adults.

BACKGROUND: The aim of the present study was twofold: (1) to assess the reproducibility of two dynamometers in handrail format to measure handgrip strength and traction force in the young and older adults; (2) to compare the handgrip strength and traction of these two populations. APPROACH: Twenty-four volunteers (12 older adults and 12 young adults) performed a functional effort related to handgrip strength and traction force during stair climbing. The participants were evaluated two times (separated by one week) using a coupled dynamometer that quantifies the muscular effort in grip and traction simultaneously to simulate stair climbing in bus service. RESULTS: The young adults performed significantly better (p < 0.04) than the older adults in both handgrip and traction efforts (medium to large effect size), with excellent reliability (Intraclass Coefficient Correlation > 0.9) and low error of measure. The dynamometers were able to discriminate the two population groups (sensitive validity) and showed excellent reproducibility estimates for handgrip and traction strength in both young and older adults. CONCLUSION: These instruments could be useful in assessing handgrip and traction strength needed to climb stairs, especially for the older adults, who normally have more difficulty performing this task.

How many balance task trials are needed to accurately assess postural control measures in older women?

Taking the average of different trials is recommended for better balance assessment, but few studies have really proven this point under different balance conditions. OBJECTIVE: To assess the effects of averaging trials of five different balance tasks on postural control measures in older women. METHODS: A total of 90 older women (means: Age: 68 years; Weight: 67 kg; Height: 1.56 m; Body mass index, 27 kg/m2) participated in this study. The participants completed five balance tasks with three performance trials for each task on a force platform in random order. The participants completed a total of three 30-s trials of tasks with 30 s of rest between trials. Repeated measure ANOVA and coefficient of variation were computed to compare differences for one trial vs. averaging across two or three trials on center of pressure (COP) sway values. RESULTS: There were no significant differences (P > 0.05) in COP sway values when comparing one vs. the average of two or three trials for all balance tasks. However, the coefficient of variation was higher for three trials (10-40%) than two (6-37%) or one trial (3-23%) for COP parameters. CONCLUSIONS: Based on reduction of variability, the present study recommends the averaging of a minimum of two trials for balance assessment in older women. The results of the current study have implications for balance assessment in older people in fall prevention programs.

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.

Can functional exercise capacity discriminate older individuals with poor postural control? / A capacidade funcional de exercício pode discriminar idosos com pior controle postural? / La capacidad funcional de ejercicio puede discriminar ancianos con mal control postural?

Postural instability can be related to functional limitations as a result of the aging process. This study aimed to compare functional exercise capacity and postural control in older adults. Participants were allocated into three groups according to their functional exercise capacity based on the six minute walking test (6MWT): 1) Low performance group (LP: distance walked ≤ 80% of the predicted value n = 19), 2) Normal performance group (NP: distance walked 81-100% of the predicted value n = 21) and, 3) High performance group (HP: distance walked >100% of the predicted value n = 23). All groups performed three trials of a one-leg stance for 30s on a force platform. LP showed worse postural control in comparison to NP and HP, and significant differences (p < .05) were found between groups for area, velocity antero-posterior of center of pressure and time limit variables during the one-leg stance task. These results have implications for rehabilitation management with regard to exercise, balance assessment and intervention in older adults.

Instabilidade postural pode estar relacionada com as limitações funcionais, como um resultado do processo de envelhecimento. Este estudo teve como objetivo comparar a capacidade funcional de exercício e o controle postural em indivíduos idosos. Os participantes foram separados em três grupos de acordo com sua capacidade funcional de exercício baseada no teste de caminhada de seis minutos (TC6min): 1) grupo baixo desempenho (BD: distância caminhada ≤ 80% do valor predito n = 19), 2) grupo normal desempenho (ND : distância caminhada 81-100% do valor predito n = 21) e, 3) grupo alto desempenho (AD: distância caminhada >100% do valor predito n = 23). Todos os grupos realizaram três testes com apoio unipodal permanecendo por 30s sobre a plataforma de força. BD apresentou pior equilíbrio postural em comparação com ND e AD; com diferenças significativas (p < 0,05) encontradas entre os grupos para os parâmetros de área e velocidade antero-posterior do centro de pressão e a variável tempo-limite durante a posição unipodal. Estes resultados têm implicações para estratégias de reabilitação no que diz respeito ao exercício, avaliação do equilíbrio e intervenção em idosos.

Inestabilidad postural puede estar relacionada con las limitaciones funcionales como resultado del proceso de envejecimiento. Este estudio tuvo como objetivo evaluar la comparación entre la capacidad funcional del ejercicio en el control postural de las personas de edad avanzada. Los participantes fueron divididos en tres grupos de acuerdo a su capacidad de ejercicio funcional basado en la Prueba de Caminada de seis minutos (PC6M): 1) grupo Bajo Rendimiento (BR: distancia recorrida ≤ 80% del valor predijo, n = 19), 2) grupo Normal Rendimiento (NR: distancia recorrida 81-100% del valor predijo, n = 21) y 3) grupo Alto Rendimiento (AR: distancia recorrida >100% del valor predijo, n = 23). Todos los grupos realizaron tres pruebas sobre un solo pie por 30s en la plataforma de fuerza. BR presentó un mal equilibrio postural en comparación con NR y AR; con diferencias significativas (p < 0,05) encontrado entre los grupos de los parámetros área y velocidad antero-posterior del centro de presión y el límite de tiempo para la postura de una sola pierna. Estos resultados tienen implicaciones para las estrategias de rehabilitación en relación con el ejercicio, la evaluación del equilibrio y la intervención en los ancianos.

Relationship between foot posture measurements and force platform parameters during two balance tasks in older and younger subjects.

[Purpose] The aim of this study was to compare age-related differences in balance and anthropometric posture measurements of the foot and to determine any relationship between them. [Subjects and Methods] Sixty-eight older and 42 younger adults participated in this study. Foot posture was tested for four domains: 1) hallux flexion and extension range of motion using a goniometer, 2) navicular height and 3) length of the foot using a pachymeter, and 4) footprint (width of forefoot, arch index and hallux valgus). Balance was tested under two conditions on a force platform: bipodal in 60-s trials and unipodal in 30-s trials. The sway area of the center of pressure and velocity in the anteroposterior and mediolateral directions were computed. [Results] Older individuals showed significantly poorer balance compared with younger adults under in the unipodal condition (center of pressure area 9.97 vs. 7.72 cm(2)). Older people presented a significantly lower hallux mobility and higher values for width of the forefoot and transverse arch index than younger adults. The correlations between all foot posture and center of pressure parameters varied across groups, from weak to moderate (r -0.01 to -0.46). Low hallux mobility was significantly related to higher center of pressure values in older people. [Conclusion] These results have clinical implications for balance and foot posture assessments.

Effect of trunk extensor fatigue on the postural balance of elderly and young adults during unipodal task.

Muscle fatigue can influence the various mechanisms that regulate balance. Few studies have investigated the effects of trunk extensor muscle fatigue on postural control. The purpose of this study was to evaluate the impact of trunk extensor fatigue during a one-leg balance test in young and elderly adults, as well as to determine the time necessary to recover posture control after fatigue. A total of 36 subjects (18 elderly and 18 young adults) participated in the study. Subjects were tested on a force platform to assess the postural control parameters associated with center of pressure (COP) movements, before and after a fatiguing trunk extension-flexion exercise on a roman chair carried out to exhaustion. Post-fatigue effects and postural control recovery were investigated at different times in minutes (MIN): immediately post-fatigue (postIME), after 5 (rec5MIN), 10 (rec10MIN), and 20 min (rec20MIN). Elderly subjects had greater sway (P < 0.05) than young adults in all COP parameters. In both groups, there was an increase in postIME sway compared with pre-fatigue values for all COP parameters. However, the differences were significant only for the COP velocity parameter, with more pronounced effects in young adults that did not return to pre-fatigue values at the end of rec20MIN. The present study demonstrated a significant effect of trunk extensor muscle fatigue on postural control, which was more evident in young adults than in the elderly.

Relationship between force platform and two functional tests for measuring balance in the elderly / Relação entre plataforma de força e dois testes funcionais para medidas de equilíbrio em idosos

BACKGROUND: Clinical and laboratory methods have been developed to assess the different dimensions of postural control with the aim to increase the clinical relevance of decisions about balance deficit. Objectives: The purpose of this study was to correlate the force platform measurements with two functional tests used to evaluate balance in elderly. METHODS: A total of 124 physically independent elderly volunteers participated in this study. Subjects performed the following three tests: 1) a traditional functional balance test, named the one-leg standing test, which measures the time in seconds at this position; 2) a functionalagility/dynamic balance test, which quantifies the total time in seconds that a subject canstand up from a chair and move as quickly as possible around two cones; and 3) an unipodal balance test on a force platform. RESULTS: The one-leg standing test yielded a mean of 12 seconds (SD=9 s), while the mean time observed in the functional agility/dynamic balance test was 26 seconds (SD=6 s). The correlations between the balance parameters of force platform and two functional tests varied between -0.28 and 0.20, which shows a weak association between them. CONCLUSIONS: Our results support the idea that these functional tests do not necessarily furnish the same information regarding balance mechanisms as the force platform. This study contributes to the evaluation of balance in elderly and suggests that functional tests should be used with caution especially in regards to the purposes of the research and when conducting clinical assessments of the elderly.

CONTEXTUALIZAÇÃO: Diferentes métodos clínicos e laboratoriais têm sido desenvolvidos para avaliar as dimensões do controle postural a fim de aumentar a relevância clínica nas decisões quanto ao déficit de equilíbrio. Objetivos: Correlacionar as medidas de plataforma de força com dois testes funcionais usados para avaliar o equilíbrio em idosos. MÉTODOS: Cento e vinte e quatro idosos fisicamente independentes e voluntários participaram deste estudo. Os sujeitos realizaram três testes: 1) teste tradicional e funcional de equilíbrio estático, que mede o tempo-limite em segundos de apoio unipodal; 2) teste funcional de agilidade e equilíbrio dinâmico, que quantifica o tempo total em segundos para realizar uma tarefa de sentar, levantar e locomover-se o mais rápido possível em torno de dois cones e 3) teste de equilíbrio unipodal sobre uma plataforma de força. RESULTADOS: A média do tempo-limite para o teste funcional de equilíbrio estático foi de 12 segundos (DP=9s), enquanto a média de tempo para o teste funcional de agilidade e equilíbrio dinâmico foi de 26 segundos (DP=6s). As correlações entre os parâmetros de equilíbrio da plataforma de força e os testes funcionais variaram entre -0,28 e 0,20, sugerindo uma associação fraca entre eles. CONCLUSÕES: Os resultados suportam a ideia de que os dois testes funcionais não fornecem, necessariamente, a mesma informação que uma plataforma fornece quanto aos mecanismos de controle postural para equilíbrio. Este estudo colabora para a avaliação do equilíbrio em idosos e sugere que alguns testes funcionais deveriam ser usados com mais cautela quanto à sua indicação no alcance dos objetivos da pesquisa e na identificação dos possíveis déficits de equilíbrio, especialmente quando usados para avaliação clínica de idosos.

Relationship between force platform and two functional tests for measuring balance in the elderly.

BACKGROUND: Clinical and laboratory methods have been developed to assess the different dimensions of postural control with the aim to increase the clinical relevance of decisions about balance deficit. OBJECTIVES: The purpose of this study was to correlate the force platform measurements with two functional tests used to evaluate balance in elderly. METHODS: A total of 124 physically independent elderly volunteers participated in this study. Subjects performed the following three tests: 1) a traditional functional balance test, named the one-leg standing test, which measures the time in seconds at this position; 2) a functional agility/dynamic balance test, which quantifies the total time in seconds that a subject can stand up from a chair and move as quickly as possible around two cones; and 3) an unipodal balance test on a force platform. RESULTS: The one-leg standing test yielded a mean of 12 seconds (SD=9 s), while the mean time observed in the functional agility/dynamic balance test was 26 seconds (SD=6 s). The correlations between the balance parameters of force platform and two functional tests varied between -0.28 and 0.20, which shows a weak association between them. CONCLUSIONS: Our results support the idea that these functional tests do not necessarily furnish the same information regarding balance mechanisms as the force platform. This study contributes to the evaluation of balance in elderly and suggests that functional tests should be used with caution especially in regards to the purposes of the research and when conducting clinical assessments of the elderly.