Sinusoidal vibrotactile stimulation differentially improves force steadiness depending on contraction intensity.

Studies have reported the benefits of sensory noise in motor performance, but it is not clear if this phenomenon is influenced by muscle contraction intensity. Additionally, most of the studies investigated the role of a stochastic noise on the improvement of motor control and there is no evidence that a sinusoidal vibrotactile stimulation could also enhance motor performance. Eleven participants performed a sensorimotor task while sinusoidal vibrations were applied to the finger skin. The effects of an optimal vibration (OV) on force steadiness were evaluated in different contraction intensities. We assessed the standard deviation (SD) and coefficient of variation (CoV) of force signals. OV significantly decreased force SD irrespective of contraction intensity, but the decrease in force CoV was significantly higher for low-intensity contraction. To the best of our knowledge, our findings are the first evidence that sinusoidal vibrotactile stimulation can enhance force steadiness in a motor task. Also, the significant improvement caused by OV during low-intensity contractions is probably due to the higher sensitivity of the motor system to the synaptic noise. These results add to the current knowledge on the effects of vibrotactile stimulation in motor control and have potential implications for the development of wearable haptic devices. Graphical abstract In this work the effects of a sinusoidal vibrotactile stimulation on force steadiness was investigated. Index finger sensorimotor tasks were performed in three levels of isometric contraction of the FDI muscle: 5, 10 and 15 %MVC. An optimal level of vibration significantly improved force steadiness, but the decrease in force CoV caused by vibration was more pronounced in contractions at 5 %MVC.

Alterações posturais, de equilíbrio e dor lombar no período gestacional / Changes of posture, equilibrium and low back pain during pregnancy

Durante a gravidez, a mulher passa por transformações morfológicas e fisiológicas que requerem cuidados especiais. As transformações fisiológicas envolvem adaptações hemodinâmicas, hormonais e biomecânicas que, sem acompanhamento adequado, contribuem para o surgimento de desordens musculoesqueléticas. Este estudo trata-se de uma revisão da literatura com busca das referências bibliográficas na base de dados Pubmed e Scielo e teve por objetivo discutir os principais fatores fisiológicos e biomecânicos que estão associados ao surgimento de alterações posturais, de equilíbrio postural e de dor lombar durante a gravidez e revisar métodos de prevenção e alívio da dor. As alterações hemodinâmicas, hormonais e biomecânicas do corpo justificam a presença de edemas, do aumento do peso corporal, da frouxidão ligamentar e das alterações posturais comuns nas grávidas e propiciam o aparecimento de desordens musculoesqueléticas e o comprometimento do equilíbrio postural. O estudo dessas desordens é importante, pois fornece um indicativo de persistência de sintomas álgicos durante a gravidez e no pós-parto, e o conhecimento destas, bem como dos métodos de analgesia para seus sintomas, permite ao profissional de saúde a elaboração de intervenções preventivas ou o diagnóstico e o seu tratamento precoce

During pregnancy, the woman undergoes morphological and physiological changes, which require special care. Physiological changes involve hemodynamic, hormonal, and biomechanical adaptations in pregnant woman body that, without appropriate monitoring, may contribute to emerging musculoskeletal disorders. The aim of this work was to search in literature most important physiological and biomechanical factors that are associated with low-back pain along with the appearance of postural and balance changes in the pregnant woman. In addition, it was revised prevention and alleviation methods of pain. In this review, bibliographical references from the Pubmed and the Scielo databases were used, and those references that fit in the proposed theme were chosen to be discussed. Hemodynamic, hormonal and biomechanical changes are factors that justify edemas, the increasing in body weight, the ligament looseness and postural changes that are very common in pregnant women. The appearance of musculoskeletal disorders and balance impairment are frequent due these changes. Hence, the study of these disorders is relevant since they provide evidence of pain symptom persistence during pregnancy and postpartum. Besides, the understanding of these disorders as well as analgesia methods enables the health care professional to elaborate preventive interventions or early diagnoses and treatments of symptoms