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BACKGROUND: Muscle force estimation could advance the comprehension of the neuromuscular strategies that diabetic patients adopt to preserve walking ability, which guarantees their independence as they deal with their neural and muscular impairments due to diabetes and neuropathy. In this study, the lower limb's muscle force distribution during gait was estimated and compared in diabetic patients with and without polyneuropathy. METHODS: Thirty individuals were evaluated in a cross-sectional study, equally divided among controls (CG) and diabetic patients with (DNG) and without (DG) polyneuropathy. The acquired ground reaction forces and kinematic data were used as input variables for a scaled musculoskeletal model in the OpenSim software. The maximum isometric force of the ankle extensors and flexors was reduced in the model of DNG by 30% and 20%, respectively. The muscle force was calculated using static optimization, and peak forces were compared among groups (flexors and extensors of hip, knee, and ankle; ankle evertors; and hip abductors) using MANOVAs, followed by univariate ANOVAs and Newman-Keuls post-hoc tests (p < 0.05). RESULTS: From the middle to late stance phase, DG showed a lower soleus muscle peak force compared to the CG (p=0.024) and the DNG showed lower forces in the gastrocnemius medialis compared to the DG (p=0.037). At the terminal swing phase, the semitendinosus and semimembranosus peak forces showed lower values in the DG compared to the CG and DNG. At the late stance, the DNG showed a higher peak force in the biceps short head, semimembranosus, and semitendinosus compared to the CG and DG. CONCLUSION: Peak forces of ankle (flexors, extensors, and evertors), knee (flexors and extensors), and hip abductors distinguished DNG from DG, and both of those from CG. Both diabetic groups showed alterations in the force production of the ankle extensors with reductions in the forces of soleus (DG) and gastrocnemius medialis (DNG) seen in both diabetic groups, but only DNG showed an increase in the hamstrings (knee flexor) at push-off. A therapeutic approach focused on preserving the functionality of the knee muscles is a promising strategy, even if the ankle dorsiflexors and plantarflexors are included in the resistance training.

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We investigated the muscle fiber conduction velocity (MFCV) during gait phases of the lower limb muscles in individuals with various degrees of diabetic peripheral neuropathy (DPN). Forty-five patients were classified into severity degrees of DPN by a fuzzy model. The stages were absent (n=11), mild (n=14), moderate (n=11) and severe (n=9), with 10 matched healthy controls. While walking, all subjects had their sEMG (4 linear electrode arrays) recorded for tibialis anterior (TA), gastrocnemius medialis (GM), vastus lateralis (VL) and biceps femoris (BF). MFCV was calculated using a maximum likelihood algorithm with 30ms standard deviation Gaussian windows. In general, individuals in the earlier stages of DPN showed lower MFCV of TA, GM and BF, whilst individuals with severe DPN presented higher MFCV of the same muscles. We observed that mild patients already showed lower MFCV of TA at early stance and swing, and lower MFCV of BF at swing. All diabetic groups showed a markedly reduction in MFCV of VL, irrespective of DPN. Severe patients presented higher MFCV mainly in distal muscles, TA at early and swing phases and GM at propulsion and midstance. The absent group already showed MFCV of VL and GM reductions at the propulsion phase and of VL at early stance. Although MFCV changes were not as progressive as the DPN was, we clearly distinguished diabetic patients from controls, and severe patients from all others.

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INTRODUCTION: Changes in gait cadence caused by challenging situations in daily life might induce higher demand for strength and propulsion in diabetic neuropathic (DN) subjects. METHODS: Forty-six subjects (healthy and DN) walked at two cadences (self-selected and 25% higher). Kinematic and electromyographic data were obtained from lower limbs and compared across the gait cycle. RESULTS: DN subjects showed a delayed peak in plantarflexor activity along the whole cycle (irrespective of cadence) compared with healthy subjects. However, during the imposed cadence, DN individuals showed reduced ankle range of motion along the entire cycle compared with the self-selected condition and healthy individuals walking at both cadences (P = 0.002). CONCLUSIONS: These findings suggest that when diabetic individuals face a new challenging situation that induces a higher demand for muscle strength and propulsion, the necessary range of motion and neuromuscular control around distal joints are insufficient.

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INTRODUCTION: In this study we investigate the influence of diabetic neuropathy (DN) on lower limb electromyography (EMG) and kinematics during stair negotiation. METHODS: Forty-six adults (healthy and DN) performed stair ascent and descent tasks. Kinematic and EMG data were assessed unilaterally. RESULTS: DN patients had lower ankle dorsiflexion while ascending and plantarflexion while descending. This reduced dorsiflexion compromises proper ankle and knee positions necessary for an efficient lifting action by the vastus lateralis (VL). The mechanical disadvantage of VL at the beginning of the stance triggered prolonged VL activation at the end of stair ascent. In stair descent, DN patients showed lower tibialis anterior activity in the early phase that can potentially impair the mechanism of impact absorption when the forefoot contacts the step. CONCLUSIONS: Our results reveal an adaptive motor strategy in DN patients to overcome the challenge of stair ascent, which promoted more biomechanical deficits.

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To obtain a high quality EMG acquisition, the signal must be recorded as far away as possible from muscle innervations and tendon zones, which are known to shift during dynamic contractions. This study describes a methodology, using commercial bipolar electrodes, to identify better electrode positions for superficial EMG of lower limb muscles during dynamic contractions. Eight female volunteers participated in this study. Myoelectric signals of the vastus lateralis, gastrocnemius medialis, peroneus longus and tibialis anterior muscles were acquired during maximum isometric contractions using bipolar electrodes. The electrode positions of each muscle were selected assessing SENIAM and then, other positions were located along the length of muscle up and down the SENIAM site. The raw signal (density), the linear envelopes, the RMS value, the motor point site, the position of the IZ and its shift during dynamic contractions were taken into account to select and compare electrode positions. For vastus lateralis and peroneus longus, the best sites were 66% and 25% of muscle length, respectively (similar to SENIAM location). The position of the tibialis anterior electrodes presented the best signal at 47.5% of its length (different from SENIAM location). The position of the gastrocnemius medialis electrodes was at 38% of its length and SENIAM does not specify a precise location for signal acquisition. The proposed method should be considered as another methodological step in every EMG study to guarantee the quality of the signal and subsequent human movement interpretations.

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Na prática fisioterapêutica, pressupõe-se que alterações posturais do membro inferior influenciem a biomecânica e função dos demais complexos durante o movimento. No entanto, a literatura sobre a relação entre desalinhamentos estáticos do joelho e possíveis alterações dinâmicas ainda é escassa e inconclusiva. Assim, buscou-se avaliar o efeito do alinhamento frontal estático do joelho sobre a distribuição da pressão plantar durante a marcha. Foram avaliados inicialmente 44 adultos jovens assintomáticos. Por fotogrametria digital, mediu-se o ângulo frontal do joelho, classificado como normal (170° a 175°), valgo <170º e varo >175°. Dado o baixo número de valgos, foram analisados dois grupos: de joelhos normais (n=18) e de joelhos varos (n=23). A distribuição da pressão plantar foi avaliada durante a marcha em cinco áreas. Os grupos mostraram-se estatistica-mente semelhantes em todas as variáveis cinéticas avaliadas em todas as áreas plantares. Joelhos normais apresentaram significativa correlação com o tempo de contato no antepé lateral e médio-pé; e os varos, correlação com a área e tempo de contato em duas e três áreas plantares, e com a pressão integral no antepé lateral. Os resultados mostraram que o desalinhamento frontal de 3° do joelho, embora com moderada correlação, não influencia a distribuição de cargas na superfície plantar durante a marcha. Sugere-se pois que a avaliação clínica não se limite à avaliação articular estática do joelho, mas inclua atividades dinâmicas...

In physical therapy practice, it is assumed that lower-limb posture changes may influence other complexes’ biomechanics or function during movement. However, literature on the relationship between static knee alignment and possible dynamic changes is still scarce and inconclusive. This study assessed the effect of static frontal knee alignment on plantar pressure distribution during gait. At first 44 young asymptomatic adults were evaluated. Front knee angles were measured by digital photogrammetry and classified as normal (170° to 175°), valgus <170°, or varus >175°. Given the low number of valgus found, two groups were analysed: normal knees (n=18) and varus knees (n=23). Plantar pressure distribution was measured during gait in five plantar surface areas. Groups were found to be statistically similar in all kinetic variables assessed in all plantar surface areas. Normal knees showed significant correlation with the contact time at lateral forefoot and midfoot. Varus knees showed correlation with contact area and time at respectively two and three plantar areas, and with full pressure at lateral forefoot. Results thus show that a 3° frontal knee malalignment, though with moderate correlation, does not influence pressure distribution on plantar surface during gait. It is hence suggested that clinical evaluation should not be limited to static knee assessment, but rather include dynamic activities.

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Nota-se um crescente aumento das queixa de dores na coluna e nos membros em motoristas que permanecem em posturas inadequadas por longos periodos que pode se atribuido ao...

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