Hip, Knee, and Ankle Functional Demand During Habitual and Fast-Pace Walking in Younger and Older Women.

This study compared functional demand (FD) between older and younger women walking at habitual and fast speed and determined strength thresholds necessary to maintain FD below 80%. FD was calculated by expressing walking flexion and extension joint torques of the ankle, knee, and hip as a percentage of maximal strength. Young women had an average FD of 65% across joint actions and speeds, whereas older women had FD of 90%. In older women, the greatest FD occurred in the hip musculature. The hip, knee, and ankle extensor strengths required to maintain FD below 80% were 1.66, 1.86, and 0.57 Nm/kg, and flexor strengths were 1.24, 0.49, and 0.69 Nm/kg, respectively. Older women have limited functional reserve to increase gait speed and rely heavily on available hip strength during walking. This study identifies strength targets for the hip, knee, and ankle that will assist in maintaining FD of older women at a sustainable level.

Peak torque, reaction time, and rate of torque development of hip abductors and adductors of older women.

Impaired muscle function at the hip has been implicated to be a major factor related to falls in older adults. Therefore, the aim of this study was to analyze the rate of torque development (RTD), reaction time (RT), and peak torque (PT) of hip abductors and hip adductors in young women (YW), older women nonfallers (ONF), and older women fallers (OF). Eighteen YW and 44 older women divided among OF (n = 20) and ONF (n = 24) performed maximum isometric hip abductor and adduction contractions on a dynamometer. YW had 40% greater PT and 61.5% greater RTD for hip abductors than the ONF. Compared with OF, YW had 47.5% greater PT and 68% greater RTD. OF showed less RTD at 150 ms (31%) and 200 ms (34.5%) than ONF for hip abductors. PT of hip adductors was 52% greater in YW than in the two older groups, whereas RTD was 71% greater. OF showed less RTD than ONF for hip abductors according to standardized effect sizes. No RT differences were observed between the three groups. We conclude that older women (OF and ONF) have less strength and ability to develop force rapidly than YW for hip abductors and adductors. Low hip strength and slowed force development in ONF during hip abduction may increase fall risk in older women.

Age-related alterations in the activation of trunk and lower limb muscles during walking.

BACKGROUND: Walking is a complex motor task that requires an integrated coordination of the trunk, lower limb, and upper limb movements. Previously, few studies have investigated the activation pattern of trunk muscles during walking. However, the mechanisms by how aging affects the recruitment of trunk muscles during walking remain unclear. OBJECTIVE: The present study aimed to compare the activation of trunk and lower limb muscles during walking in younger and older women. METHODS: Fifteen younger women between 18 and 30 yr and 19 older women between 60-82 yr walked on the treadmill at a self-selected speed, while 1-min surface electromyography (EMG) signals were recorded from the multifidus, internal oblique, gluteus maximus, rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius lateralis. EMG signals were processed and a linear envelope was calculated at an initial stance (50 ms after heel contact) and final stance (50 ms before toe-off). RESULTS: Compared with younger women, older women had 52.32% lower activation of the internal oblique (p = 0.027) and 39.95% lower activation of the rectus femoris (p = 0.003) at initial stance. CONCLUSION: Results of this study demonstrated that older women had lower activation of trunk and knee muscles during the initial stance, which may have resulted from weakness and balance impairments caused by aging.

A órtese não influencia no desempenho de indivíduos com instabilidade do tornozelo / The orthosis had no influence on the performance of individuals with ankle instability

Introdução: A instabilidade funcional do tornozelo (IFT) é uma das consequências das entorses de tornozelo, que podem gerar déficits de funcionalidade. Um dos métodos utilizados para avaliar esses déficits são testes funcionais (TF), além disso, pode-se prevenir a entorse usando órteses de tornozelo, no entanto, ambos os métodos ainda são controversos na literatura. Objetivo: Comparar o desempenho de indivíduo com e sem IFT em testes funcionais com e sem o uso da órtese de tornozelo. Método: Vinte e duas voluntárias na faixa etária entre 18 e 25 anos participaram do estudo e foram divididas em grupo controle e grupo com IFT. As mulheres realizaram cinco testes funcionais com e sem o uso de órtese de tornozelo. Resultados: Não foi encontrada diferença significativa entre os grupos e nem entre as condições. Conclusão: A órtese de tornozelo não influenciou no desempenho de indivíduos com e sem IFT em testes funcionais.

Introduction: Functional ankle instability (FAI) is a consequence of ankle sprains, which can generate functional deficits. One of the methods used to evaluate these deficits are the functional tests (FT), in addition, one method of preventing ankle sprains are the orthosis, however, both methods are still controversial. Objective: To compare the performance of individuals with and without IFT in functional tests with and without the use of ankle orthosis. Method: Twenty-two volunteers aged 18 to 25 years participated in the study and were divided into a control group and a group with IFT. The subjects performed five functional tests with and without the use of ankle orthosis. Results: No significant difference was found between groups and between conditions. Conclusion: The ankle orthosis had no influence on the performance of individuals with and without FAI in functional tests.

Electromyographic reaction time in older female fallers and non-fallers after postural perturbation / Tempo de reação eletromiográfica em idosas caidoras e não-caidoras após desequilíbrio postural

The electromyographic reaction time (ERT) reflects the magnitude and speed with which muscles are activated to perform movements, to prevent injuries, or to position a joint. This parameter can be used to analyze postural control performance after an external perturbation and can be correlated with the possibility of falls in older adults. The objective of this study was to determine the ERT of the internal oblique, rectus femoris, vastus lateralis, tibialis anterior, multifidus, gluteus maximus, biceps femoris, and lateral gastrocnemius muscles to balance threats in older adults with and without a history of falls. Twenty-nine physically active and noninstitutionalized women aged 60 years or older were divided into two groups: fallers (n=13; 72.4 ± 8.0 years) and non-fallers (n=16; 67.8 ± 6.8 years). The ERT of the muscles tested did not differ significantly between groups following forward or backward perturbations. The results suggest that the activation of the muscles tested in response to forward or backward perturbations is not a determinant factor of falls.

O tempo de reação eletromiográfica (TRE) reflete a magnitude e a velocidade com que os músculos são ativados para realizar movimentos, evitar lesões ou posicionar uma articulação e pode ser avaliado após uma perturbação externa para análise do desempenho do controle postural e relacioná-lo com a possibilidade de quedas em idosos. O objetivo do estudo foi verificar o TRE dos músculos oblíquo interno (OI), reto femoral (RF), vasto lateral (VL), tibial anterior (TA), multífido (MU), glúteo máximo (GM), bíceps femoral (BF) e gastrocnêmio lateral (GL) em situações de perturbação do equilíbrio em idosos com e sem histórico de quedas. Para isso, foram avaliadas vinte e nove mulheres com 60 anos ou mais, fisicamente ativas e não-institucionalizadas e separadas em dois grupos de acordo com o relato de quedas nos 12 meses pregressos ao estudo: Grupo de Idosas Caidoras (GIC) (n=13; 72,4 ± 8,0 anos) e Grupo de Idosas Não-Caidoras (GINC) (n=16; 67,8 ± 6,8 anos). O TRE dos músculos avaliados durante o teste de desequilíbrio postural anterior e posterior não foram significativamente diferentes entre os grupos. Os resultados sugerem que a ativação muscular dos músculos avaliados, tanto durante o desequilíbrio anterior quanto no desequilíbrio posterior, não podem ser considerados um fator determinante para quedas.

Association between energy cost of walking, muscle activation, and biomechanical parameters in older female fallers and non-fallers.

OBJECTIVE: To determine the nervous activation, muscle strength, and biomechanical parameters that influence the cost of walking in older fallers and non-fallers. METHODS: Maximal voluntary isokinetic torque was measured for the hip, knee and ankle of older women. Oxygen consumption was measured at rest and during 8min of walking at self-selected speed. An additional minute of walking was performed to collect kinematic variables and the electromyographic signal of trunk, hip, knee, and ankle muscles, which was analyzed by the linear envelope. Cost of walking was calculated by subtracting resting body mass-normalized oxygen consumption from walking body mass-normalized oxygen consumption. Stride time and length, and ankle and hip range of motion were calculated from kinematic data. FINDINGS: Older adult fallers had 28% lower knee extensor strength (p=0.02), 47% lower internal oblique activation at heel contact (p=0.03), and higher coactivation between tibialis anterior and gastrocnemius lateralis in each of the gait phases (p<0.05). For fallers, a higher activation of gluteus maximus was associated with a higher cost of walking (r=0.55, p<0.05 and r=0.71, p<0.01, before and after heel contact, respectively). For non-fallers, an association between cost of walking and age (r=0.60, p=0.01) and cost of walking and thigh muscle coactivation (r=0.53, p=0.01) existed. INTERPRETATION: This study demonstrated that there may be links between lower-extremity muscle weakness, muscle activation patterns, altered gait, and increased cost of walking in older fallers.

Efeito da simulação do jogo de basquetebol sobre o pico de torque e razão funcional dos músculos estabilizadores do tornozelo / Effect of basketball match simulation on peak torque and functional torque ratio of stabilizing muscle of the ankle

O presente estudo teve por objetivo analisar o efeito de simulação do jogo de basquetebol sobre o pico de torque (PT) dos músculos eversores e inversores do tornozelo e a razão de torque funcional eversor excêntrico/inversor concêntrico (EVEEXC/INVCON). Dez basquetebolistas universitários saudáveis, sem instabilidades mecânicas ou funcionais no tornozelo realizaram uma simulação do jogo de basquetebol a partir de um teste laboratorial. O teste foi composto por uma sucessão de esforços físicos intensos e breves distribuídos igualmente em quatro períodos de 10 minutos cada, considerando demandas mecânicas e fisiológicas de um jogo de basquetebol. Previamente ao início do teste (Avaliação 1) e após o 2º (Avaliação 2) e o 4º (Avaliação 3) período, foram realizadas cinco contrações isocinéticas máximas concêntricas e excêntricas dos grupos musculares eversores e inversores do tornozelo, separados por dois minutos de intervalo, nas velocidades de 60º/s e 120°/s. Após a verificação da normalidade de distribuição dos dados com o teste Shapiro-Wilk, utilizou-se o teste ANOVA medidas repetidas e o teste post-hoc de Bonferroni para a comparação das variáveis entre as avaliações. Adotou-se p < 0.05. Não houve diferença significativa para a razão EVEEXC/INVCON entre as avaliações realizadas. Entretanto, verificou-se declínio do PT EVEEXC a 60º/s e 120º/s para a Avaliação 1 quando comparada à Avaliação 2. Para o PT INVCON observou-se redução dos valores em relação à Avaliação 1, quando comparados à Avaliação 2 e à Avaliação 3 a 60º/s e à Avaliação 3 a 120º/s. Diante destes resultados, conclui-se que o progresso da simulação do jogo de basquetebol promove redução do PT dos músculos eversores e inversores do tornozelo.

The aim of this study was to analyze the effect of Basketball match work simulation on peak torque (PT) of ankle evertor and invertor muscles and on eccentric evertor/concentric invertor torque ratio (EVEECC/INVCON). Ten healthy college basketball players, without mechanics or functional ankle instability performed a laboratory-based protocol representative of work rates observed during basketball match-play. The test was composed of a succession of intermittent physical effort equally distributed in four periods of 10 minutes each, considering the mechanical and physiological demands of a basketball match-play. Prior to the start of the trial (Evaluation 1) and after 2° (Evaluation 2) and 4° (Evaluation 3) period, the subjects performed five maximal isokinetic concentric and eccentric contractions of ankle invertors and evertors muscles, separated by two minutes rest, at 60 °/s and 120 °/s. After testing for normality of data distribution with the Shapiro-Wilk test, was used the ANOVA repeated measures and post-hoc Bonferroni test for comparison of variables between assessments. Was adopted p < 0.05. There was no significant difference for EVEECC/INVCON torque ratio between assessments. However, there was a decrease in PT EVEECC at 60º/s and 120º/s for the Evaluation 2 when compared to Evaluation 1. There was a reduction of PT INVCON values in relation to Evaluation 1, compared to Evaluation 2 and to Evaluation 3 at 60°/s and to Evaluation 3 at 120°/s. Given these results, we conclude that the progress of simulation basketball match-play lead a reduction on PT of the ankle evertors and invertors muscles.