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OBJECTIVE: The aging population is growing in the world, and the reduction in physical function caused by this is an important issue that, particularly, causes a disorder of balance and an increased risk of falling. This study aimed at the comparison between the effects of virtual reality training (VRT) and Conventional balance training (CBT) on the balance of the elderly. METHODS: The present study was conducted on 36 elderly (men and women) who are living in nursing homes. Participants were randomly divided into three groups: virtual reality training (6 males, 6 females; age = 66.5 ± 3.8 years), Conventional balance training (6 males, 6 females; age = 67.5 ± 3.1 years), and control (5 males, 7 females; age = 66.7 ± 3.2 years). Each group participated in a 60-min session, 3 times per week, for 9 weeks. To assess the participants' balance, the balance tests were used on single-leg stance (SLS) with open and closed eyes, Functional reach test (FRT), Timed up and Go Test (TUG), and Fullerton Advance Balance Scale (FABS). Data analysis was done using paired t-test and analysis of covariance by SPSS software version 24 at the significant level (P = 0.05). RESULTS: In both groups (VRT, CBT), SLS with open and closed eyes, FRT, TUG, and FABS were significantly improved (P˂0.05). After the intervention, changes in both groups were similar (P > 0.05), which indicates that neither VRT and CBT training methods were superior to the other. CONCLUSION: According to the results of this study, it seems that a virtual reality training program can be used as a new training method to improve the elderly's balance in daily programs of nursing homes.

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As we learn to perform a motor task with novel dynamics, the central nervous system must adapt motor commands and modify sensorimotor transformations. The objective of the current research is to identify the neural mechanisms underlying the adaptive process. It has been shown previously that an increase in muscle co-contraction is frequently associated with the initial phase of adaptation and that co-contraction is gradually reduced as performance improves. Our investigation focused on the neural substrates of muscle co-contraction during the course of motor adaptation using a resting-state fMRI approach in healthy human subjects of both genders. We analyzed the functional connectivity in resting-state networks during three phases of adaptation, corresponding to different muscle co-contraction levels and found that change in the strength of functional connectivity in one brain network was correlated with a metric of co-contraction, and in another with a metric of motor learning. We identified the cerebellum as the key component for regulating muscle co-contraction, especially its connection to the inferior parietal lobule, which was particularly prominent in early stage adaptation. A neural link between cerebellum, superior frontal gyrus and motor cortical regions was associated with reduction of co-contraction during later stages of adaptation. We also found reliable changes in the functional connectivity of a network involving primary motor cortex, superior parietal lobule and cerebellum that were specifically related to the motor learning.SIGNIFICANCE STATEMENT It is well known that co-contracting muscles is an effective strategy for providing postural stability by modulating mechanical impedance and thereby allowing the central nervous system to compensate for unfamiliar or unexpected physical conditions until motor commands can be appropriately adapted. The present study elucidates the neural substrates underlying the ability to modulate the mechanical impedance of a limb as we learn during motor adaptation. Using resting-state fMRI analysis we demonstrate that a distributed cerebellar-parietal-frontal network functions to regulate muscle co-contraction with the cerebellum as its key component.

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Adaptation to an abrupt change in the dynamics of the interaction between the arm and the physical environment has been reported as occurring more rapidly but with less retention than adaptation to a gradual change in interaction dynamics. Faster adaptation to an abrupt change in interaction dynamics appears inconsistent with kinematic error sensitivity which has been shown to be greater for small errors than large errors. However, the comparison of adaptation rates was based on incomplete adaptation. Furthermore, the metric which was used as a proxy of the changing internal state, namely the linear regression between the force disturbance and the compensatory force (the adaptation index), does not distinguish between internal state inaccuracy resulting from amplitude or temporal errors. To resolve the apparent inconsistency, we compared the evolution of the internal state during complete adaptation to an abrupt and gradual change in interaction dynamics. We found no difference in the rate at which the adaptation index increased during adaptation to a gradual compared to an abrupt change in interaction dynamics. In addition, we separately examined amplitude and temporal errors using different metrics, and found that amplitude error was reduced more rapidly under the gradual than the abrupt condition, whereas temporal error (quantified by smoothness) was reduced more rapidly under the abrupt condition. We did not find any significant change in phase lag during adaptation under either condition. Our results also demonstrate that even after adaptation is complete, online feedback correction still plays a significant role in the control of reaching.

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BACKGROUND: There is an interaction between oxidative equilibrium and anti-oxidants in oxidative stress. Therefore, oxidative stress has an effect on intercellular oxidation and causes atrophy and is an underlying factor in many diseases. OBJECTIVES: The aim of this study was to investigate the effect of running downhill and the short-term effect of caffeine supplementation on oxidative stress in non-athletic men. PATIENTS AND METHODS: Twenty men, aged 25 - 28 years, from Tabriz, Iran were been selected and divided in two homogeneous groups of 10 men: the supplementation group and the placebo group. In the next stage, groups received caffeine supplementation (caffeine capsules at a dose of 5 mg/kg of body weight daily for 14 days) or placebo (5 mg/kg of dextrose during supplementation) and ran downhill (30 minutes of treadmill running with a slope of -10 degrees with 65% maximal oxygen consumption); blood sampling was also performed. RESULTS: Anti-oxidant capacity by the ferric reducing ability of plasma (FRAP) techniques and serum malondialdehyde (MDA) were measured by the thiobarbituric acid (TBA) method, while the total number of thiol molecules (TTM) with Hu and DNA damage was evaluated using ELISA. CONCLUSIONS: The results of this study indicated that running downhill caused significant changes in all measured parameters, but the short-term caffeine supplementation did not have a significant effect on the indices of oxidative stress or DNA damage measured.

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First law of thermodynamics has been used to analyze and optimize inclusively the performance of a triple absorption heat transformer operating with LiBr/H2O as the working pair. A thermodynamic model was developed in EES (engineering equation solver) to estimate the performance of the system in terms of the most essential parameters. The assumed parameters are the temperature of the main components, weak and strong solutions, economizers' efficiencies, and bypass ratios. The whole cycle is optimized by EES software from the viewpoint of maximizing the COP via applying the direct search method. The optimization results showed that the COP of 0.2491 is reachable by the proposed cycle.

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