Effects on intermittent postural control in people with Parkinson's due to a dual task.

OBJECTIVES: The aim of the present study was to determine the effects of performing a dual task on the sway density plot parameters in Parkinson's disease and control subjects. METHODS: A cross-sectional design was used to establish differences in the mean peak, mean time, and mean distance between a group with Parkinson's disease and a control group without Parkinson's disease. The subjects performed, in a unique measurement session, two trials under three different randomized conditions: i. eyes open, ii. eyes closed, and iii. Eyes open with foam base. One trial was performed as a single task (i.e., the subjects completed one of the balance test), while the other trial was performed as a dual task (i.e., the subjects performed a cognitive task at the same time that they maintained the static balance). RESULTS: There was a group x dual task x condition effect in mean peak (F1.5, 51.1 = 5.21; p = 0.015; η2p = 0.13) and mean time (F1.4, 47.3 = 4.43; p = 0.03; η2p = 0.11) variables. According dual-task cost analysis, there was a main effect of the condition (F6,134 = 2.44; p = 0.05; η2p = 0.34) on MD (F2,68 = 6.90; p < 0.01; η2p = 0.17). CONCLUSIONS: This result indicates differences in the dual task interference in the postural control mechanisms between the Parkinson's disease population and healthy pairs. For easy dual tasks, the Parkinson subjects used anticipatory control responses for longer periods of time, and for more difficult tasks, their control strategy did not change regarding single balance task.

Comparison of conventional hamstring/quadriceps ratio between genders in level-matched soccer players / Comparación del ratio de fuerza convencional isquiotibial/cuádriceps entre jugadores de fútbol de niveles similares de ambos sexos / Comparação da relação de força convencional entre isquiotibiais/quadríceps entre jogadores de futebol com níveis semelhantes, de ambos os sexos

Objectives. The main goal of our study is to compare the hamstring/quadriceps (H/Q) ratio at different knee angles between level-matched male and female soccer players and to determine whether differences in the H/Q ratio exist between the dominant and the non-dominant leg. Methods. A cross-sectional study design was used to compare an isometric H/Q ratio and functional isokinetic ratio (between hamstring in eccentric contraction and quadriceps in concentric contraction) between males (n=14) and females (n=14). These ratios were studied at two different speeds of movement (60°s−1 and 180°s−1) and in five different positions (40°, 50°, 60°, 70° and 80° degrees of knee flexion). Results. Our results showed no differences in the H/Q ratio between genders. The ratio in the dominant leg showed an average of 9% higher values. The ratios were an average of 53.4% lower in positions near flexion than in positions near extension. Conclusions. For both men and women, the results showed lower ratios in the non-dominant leg compared to the dominant leg. At higher velocities, the force ratios were higher, while in more knee-flexed positions, the ratios were lower. Finally, we did not find differences in ratios between men and women (AU)

Objetivos. El objetivo principal del estudio es comparar el ratio de fuerza isquiotibial/cuádriceps (ratio H/Q) en diferentes ángulos de rodilla entre jugadores de fútbol de niveles similares y determinar si existen diferencias en dicho ratio entre la pierna dominante y la no dominante. Métodos. Se utilizó un diseño transversal para comparar el ratio isométrico H/Q y el ratio funcional isocinético (ratio entre la fuerza durante una contracción excéntrica de isquiotibial y la fuerza durante una contracción concéntrica de cuádriceps) entre hombres (n=14) y mujeres (n=14). Estos ratios se estudiaron en dos velocidades (60° s−1 y 180° s−1) y en 5 posiciones diferentes (40, 50, 60, 70 y 80 grados de flexión de rodilla). Resultados. Nuestros resultados no mostraron diferencias significativas en el ratio H/Q entre sexos. El ratio en la pierna dominante mostró valores un 9% más altos que en la pierna no dominante. Los ratios fueron de media un 53.4% más bajos en posiciones cercanas a la flexión que en posiciones cercanas a la extensión. Conclusiones. Para ambos sexos los resultados mostraron ratios más bajos en la pierna no dominante comparado con la pierna dominante. A velocidades superiores, los ratios de fuerza fueron mayores, mientras que en posiciones de mayor flexión de rodilla los ratios fueron menores. Por último, no se encontraron diferencias significativas en los ratios entre hombres y mujeres (AU)

Objetivos. O principal objetivo do nosso estudo é comparar a relação de força entre Isquiotibiais/Quadríceps (H/Q) em diferentes ângulos do joelho entre jogadores de futebol (masculino e feminino) de níveis semelhantes para determinar se existem diferenças na relação entre H/Q entre o membro dominante e a não-dominante. Método. U estudo de delineamento transversal foi utilizado para comparar a relação isométrica entre H/Q e isocinética funcional (razão entre a força dos isquiotibiais em contração excêntrica e do quadríceps em contração concêntrica, durante a extensão do joelho) entre homens (n=14) e mulheres (n=14). Estas razões foram estudadas em duas velocidades diferentes de movimento (60°/s e 180°/s) e em cinco posições diferentes (por exemplo 40, 50, 60, 70, e 80 graus de flexão do joelho). Resultados. Os resultados não mostraram diferenças significativas na relação H/Q entre os sexos. A relação da perna dominante mostrou valores médios de 9% mais elevados em relação a perna não dominante. As proporções foram, em média, 53,4% menor em posições próximas a flexão do que em posições perto da extensão. Conclusões. Para ambos os sexos, os resultados mostram razões mais baixas no membro não dominante em comparação com a dominante. À velocidade mais elevadas, as relações de força foram superiores, enquanto que em maiores flexões de joelho as relações foram menores. Finalmente, não foram encontradas diferenças significativas nas proporções entre homens e mulheres (AU)

The difficulty of the postural control task affects multi-muscle control during quiet standing.

The aim of this study was to compare the electromyographic (EMG) coherence between the lower limb and the core muscles when carrying out two postural tasks at different difficulty levels. EMG was recorded in 20 healthy male subjects while performing two independent quiet standing tasks. The first one involved a bipedal stance with the eyes open, while the second consisted of a dominant unipedal stance also with the eyes open. The obtained EMG signals were analysed by computing estimations of EMG-EMG coherence between muscle pairs, both singly (single-pair estimations) and combined (pooled estimations). Pooled and single coherence of anterior, posterior, core, antagonist and mixed pairs of muscles were significant in the 0-5 Hz frequency band. The results indicate that core and antagonist muscle groups, such as the anterior and posterior muscles, share low-frequency neural inputs (0-5 Hz) which could be responsible of the M-modes assembly. The core muscles could therefore provide the necessary synergy to maintain spine stability during the balancing exercise. Finally, differences in EMG-EMG coherence suggest that the muscle synergies formed during unipedal stance tasks are different from those established during bipedal stance.

Sitting balance and limits of stability in persons with paraplegia.

STUDY DESIGN: Cross-sectional, observational study of paraplegic and able-bodied persons. OBJECTIVES: The aim of the study was to analyse the temporal and frequency domains of seated balance to better understand nervous system control in equilibrium in persons with spinal cord injury (SCI) and to explore their centre of pressure (CoP) limits before experiencing a fall. SETTING: University of Valencia, Spain. METHODS: Static and dynamic seated balance were assessed in 24 paraplegic persons divided into two groups: low paraplegia group (LP) and high paraplegia group (HP), and 24 healthy volunteers with an extensiometric force plate. Two types of tests were performed: a static test (ST), where data signal was analysed by temporal and frequency domains, and a stability limit test (SLT), where different stability limits were calculated. RESULTS: The paraplegic group revealed lower static postural control in both domains in most of the parameters analysed compared with the control group (CG). Similar results were obtained with regard to the SLT, showing differences in the three parameters analysed between the CG and SCI groups. CONCLUSION: Posturographic assessment in ST was useful to explore nervous system control in equilibrium in this population, presenting a decreased balance in paraplegic groups and an altered pattern in the sensorial and cerebellum bands compared with able-bodied individuals. Furthermore, SLT indicated less movement control of the CoP in paraplegic groups, which may influence the performance of their daily activities.

Effects of resistance training on strength, pain and shoulder functionality in paraplegics.

STUDY DESIGN: Time series design. OBJECTIVES: To determine the effects of a shoulder resistance training programme on isokinetic and isometric strength, body composition, pain and functionality in paraplegic subjects. SETTING: University of Valencia, Valencia, Spain. METHODS: A total of 15 subjects with thoracic spinal cord injury (SCI) performed three testing sessions with an 8-week period between the sessions. Subjects were not disturbed between the first and the second testing sessions. Subjects performed an 8-week resistance training programme after the second testing session. Variations in isometric and isokinetic shoulder muscle strength, body composition, reported pain and shoulder functionality were evaluated. RESULTS: The training programme produced a significant increase (P<0.05) in the isometric and isokinetic strength of several shoulder movements as well as an increase (P<0.05) in arm fat-free mass and a decrease in arm fat mass (FM). Furthermore, reported pain was decreased, (P<0.05) and upper-limb functionality was increased (P<0.05). CONCLUSION: Implementing resistance training programmes as physical therapy in SCI subjects effectively increases strength, muscle mass and upper-limb functionality, whereas decreasing FM and pain perception.