Kinematics and muscle ankle action in individuals with hemiparesis during backwards walking

One of the possible mechanisms that explain the increased speed forward walking (FW) after the training backward walking (BW) in people with hemiplegia could be an increased recruitment of ankle muscles during task BW. The goal of this study is compare the muscle activation (dorsi-flexors and plantarflexors) and the range of motion of the ankle during the tasks of FW and BW in subjects with hemiparesis after stroke and healthy control subjects. The study included 12 subjects (65 ± 9 years) with chronic hemiparesis (60 ± 40 months post-stroke) and mild to moderate impairment of lower limb (LL) (FMLL 25.0 ± 4.7 points). For the control group participated in 6 healthy subjects (62.2 ± 4.6 years). The range of motion (ROM) passive isokinetic torque of the ankle at 30º / sec and corresponding EMG activity in plantarflexor muscles (PF) - Medial gastrocnemius (MG) and soleus (SOL) and dorsiflexion (DF) - Tibialis anterior (TA ) and peroneus longus (PL) was compared between the legs with ANOVA oneway. They assessed the EMG activity of the muscles and the kinematics of the ankle during the AF and AT separately in each gait sub-phase: first double support (1DS), simple support (SS), second double support (2DS) and balance sheet (BL). Data were analyzed by ANOVA, taking as factors the direction (FW and BW) and LL paretic (LLP), non-paretic (LLNP) and control (CTL). The CTL group presented DF ROM greater than the LLNP and the LLP. The PF was greater torque in relation to LLNP and LLP and LLNP was greater than in the LLP. The DF torque was lower in the LLP compared to CTL and LLNP. The spatiotemporal variables stride length, stride length and walking speed were higher in AF and higher in CTL compared to LLNP and LLP. 1DS in stages, SS and 2DS ankle ROM was higher in CTL that LLNP and LLP. In 2DS and BL CTL showed higher ROM in the BW that in FW, and 2DS in the LLNP and LLP ROM in FW was higher. The CTL group showed higher EMG activity of DF (TA and PL) and PF (MG and SOL) for all sub-phases, and only in the BL RMS of all analyzed muscles was higher in FW compared to BW. In general the CTL group had higher amplitudes and higher EMG activity that the LLP and LLNP at all stages of the march. In 2DS and BL ankle ROM was higher in the BW in the CTL group, but not in LLNP and LLP. The swing phase the EMG activity of DF and PF was higher in FW compared to FL. Future studies should evaluate whether the lower ROM identified in kinematics is related to an ankle muscle co-activation in this population.Um dos possíveis mecanismos que explicaria o aumento da velocidade do andar para frente (AF) após o treinamento do andar para trás (AT) em pessoas com hemiparesia poderia ser um maior recrutamento da musculatura do tornozelo durante a tarefa de AT. Pretendeu-se com esta pesquisa comparar a ativação muscular de dorsi e plantiflexores e a amplitude de movimento do tornozelo durante as tarefas de AF e AT entre sujeitos com hemiparesia pós-AVE e indivíduos controle saudáveis. Participaram do estudo 12 indivíduos (65±9 anos) com hemiparesia crônica (60±40 meses pós-AVE) e comprometimento leve a moderado de membro inferior (MI) (FMMI 25,0±4,7 pontos). Para o grupo controle participaram 6 indivíduos saudáveis (62,2±4,6 anos). A amplitude de movimento (ADM) passiva, o torque isocinético do tornozelo a 30º/s e a atividade EMG correspondente na musculatura plantiflexora (PF) (Gastrocnêmio Medial (GM) e Solear (SOL)) e dorsiflexora (DF) (Tibial Anterior (TA) e Fibular Longo (FL)) foram comparados entre os MI com a ANOVA de uma via. Foram avaliadas a atividade EMG da musculatura e a cinemática do tornozelo durante o AF e o AT separadamente em cada subfase da marcha: primeiro duplo apoio (1DA), apoio simples (AS), segundo duplo apoio (2DA) e balanço (BL). Os dados foram analisados através da ANOVA de duas vias, tendo como fatores a direção (AF e AT) e o MI (parético (MIP), não parético (MINP) e controle (CTL)). O grupo CTL apresentou ADM de DF maior que o MINP e que o MIP. O torque de PF foi maior no CTL em relação ao MINP e ao MIP e no MINP foi maior que no MIP. O torque de DF foi menor no MIP em relação ao CTL e MINP. As variáveis espaço-temporais comprimento da passada, comprimento do passo e velocidade de marcha foram maiores no AF em relação ao AT e maiores no CTL comparativamente ao MINP e MIP. Nas fases 1DA, AS e 2DA a ADM do tornozelo foi maior nos CTL que MINP e MIP. No 2DA e BL os CTL apresentaram maior ADM no AT que no AF, sendo que no 2DA o MINP e MIP a ADM no AF foi maior. O grupo CTL apresentou maior atividade EMG dos DF (TA e FL) e PF (GM e SOL) durante todas as subfases, sendo que apenas no BL a RMS de todos os músculos analisados foi maior no AF comparativamente ao AT. No 2DA e no BL a ADM do tornozelo foi maior no AT no grupo CTL, mas não nos MINP e MIP. O grupo CTL apresentou maiores amplitudes e maior atividade EMG que o MIP e MINP em todas as fases da marcha. Na fase de balanço a atividade EMG dos DF e PF foi maior no AF comparativamente ao AT.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio

Anticipatory and Compensatory Postural Adjustments in Response to External Lateral Shoulder Perturbations in Subjects with Parkinson's Disease.

The purpose of this study was to investigate the anticipatory (APA) and compensatory (CPA) postural adjustments in individuals with Parkinson's disease (PD) during lateral instability of posture. Twenty-six subjects (13 individuals with PD and 13 healthy matched controls) were exposed to predictable lateral postural perturbations. The electromyographic (EMG) activity of the lateral muscles and the displacement of the center of pressure (COP) were recorded during four time intervals that are typical for postural adjustments, i.e., immediately before (APA1, APA2) and after (CPA1 and CPA2) the postural disturbances. The magnitude of the activity of the lateral muscles in the group with PD was lower only during the CPA time intervals and not during the anticipatory adjustments (APAs). Despite this finding, subjects with PD exhibit smaller COP excursions before and after the disturbance, probably due to lack of flexibility and proprioceptive impairments. The results of this study suggest that postural instability in subjects with PD can be partially explained by decreased postural sway, before and after perturbations, and reduced muscular activity after body disturbances. Our findings can motivate new studies to investigate therapeutic interventions that optimize the use of postural adjustment strategies in subjects with PD

Characteristics of the participants in the control group.

<p>Characteristics of the participants in the control group.</p

Schematic representation of the pendulum used to induce the postural disturbances.

<p>The participants kept their head rotated 30 degrees toward the pendulum. 1: pendulum, 2: pulley system, 3: load attached to the pendulum, 4: ball and the accelerometer, 5: distance of the pendulum release (0.8 m), 6: safety belt.</p

Characteristics of the participants in the control group.

<p>Characteristics of the participants in the control group.</p

Anticipatory (APA1 and APA2) and compensatory (CPA1 and CPA2) time intervals for the GM, EO and PE right and left lateral muscles for each group (average across 13 subjects).

<p>*Significant differences between groups (P<0.05).</p

Means and standard errors of the center of pressure displacement in mediolateral (COPml) (right panel) and anteroposterior directions (COPap) (left panel) for the control and PD groups during the 4 time intervals for anticipatory (APA1 and APA2) and compensatory (CPA1 and CPA2) postural adjustments.

<p>The positive and negative signs in mediolateral direction represent the left and right sides, respectively. The positive signs denote anterior displacement while negative signs represent posterior excursion.</p

Characteristics of the participants with Parkinson’s disease.

<p>Characteristics of the participants with Parkinson’s disease.</p

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved