درخت حوزه‌های تخصصی

Background: Anodal transcranial direct current stimulation (a-tDCS) is a new neuro-modulatory technique.Aim: This study aimed to investigate the effect of a-tDCS on dynamic balance after exhaustion.Material and Methods: Fifteen endurance-trained men voluntarily attended five separate sessions. In the first session, Maximal aerobic speed (MAS) was measured. Then, the participants were randomly assigned to four different conditions: 1. Mental fatigue (MF)+a-tDCS, 2. MF+sham (s-tDCS), 3. a-tDCS, and 4. s-tDCS. In each session, after dynamic balance measurement, the participants were exposed to the conditions and received 20 min of anodal tDCS over the dorsolateral prefrontal cortex (DLPFC). Then, the participants performed a submaximal endurance activity at 70% of MAS until exhaustion. Immediately after exhaustion, dynamic balance was measured again.Results: After exhaustion, the dynamic balance of the right leg under the a-tDCS condition was significantly higher than the MF+s-tDCS (P= 0.008). The dynamic balance significantly decreased from pre- to post-test in MF+s-tDCS and s-tDCS conditions (P= 0.0001). In the left leg, the dynamic balance under the a-tDCS condition was significantly higher than MF+s-tDCS (P= 0.025).Conclusions: Anodal stimulation of the DLPFC could be beneficial for the dynamic balance and may have a protective effect against the negative consequence of exhausting activity on the dynamic balance in endurance-trained men.

Background: Observational learning is an effective pedagogical approach that can be used as a method to improve motor skill acquisition and also a useful instrument to promote psychological variables such as self-efficacy by emphasizing the motivational aspect. Although, little research is known about the model type and the observation conditions which will optimize learning. Aim: This study aimed to clarify the effect of using a combination of ideal model-observation and self-observation on self-efficacy and learning the forehand service of table tennis. Materials and Methods: Forty females were assigned to one of four experimental groups. All groups received the same instructions concerning how to perform the task, filled out a self-efficacy questionnaire, and then performed 10 pre-test trials. The acquisition phase included six sessions. The retention test was done 72 hours after the last acquisition session. Mixed ANOVA with repeated measures and Bonferroni post hoc tests were conducted, and one-way ANOVA was used to determine group significant differences. Results: The results indicated that observing the combination of skilled and learning models led to the highest self-efficacy for learning, compare with other experimental models. Also, significant learning of the task was shown in the acquisition phase in which the performance of all three experimental groups was clearly superior to the control group. Although in this phase there was no significant difference between the performances of two groups of combined skilled-learning and skilled. The results of the delayed retention test indicated that the performance scores of the combined skilled-learning group were significantly higher than the other three groups. Also, in this phase, the difference between the combined skilled self-observation and control or skilled groups was not significant. Conclusion: Demonstrating a skilled model is the most popular type of observational learning among the instructors and physical education teachers, it is suggested that adding a learning model to that leads to better performance and enhancing the self-efficacy.

Background: Osteoporosis is a decrease in bone density among older adults that can lead to painful fractures and disability. People in developing countries are not interested in examining bone mineral density until fractures occur. Therefore, the aim of this study was to investigate the relationship between the indicators affecting osteoporosis with femoral mineral density in active and inactive elderly men.Methods: A total of 45 active and 45 inactive men with an age range of 70 to 85 years with medical records and clinical trials were selected. Anthropometric characteristics and serum indices of the subjects were used as effective indicators of osteoporosis. Pearson correlation coefficient was used to find the relationship between the indicators and the mineral density of the femur. SPSS software version 26 was used for data analysis.Results: The results of the present study showed that in both groups of active and inactive elderly men, a significant relationship was observed between anthropometric characteristics and serum indices with bone mineral density (P≤0.05). No significant relationship was found between other indicators.Conclusion: In general, the results show that there is a significant relationship between bone density and weight, body mass index, age, calcium, phosphorus and serum alkaline phosphatase of all subjects. Therefore, in adulthood and old age, these blood and anthropometric variables can be used to identify people at risk for osteoporosis.