درخت حوزه‌های تخصصی

Purpose: The aim of this study was to investigate the acute effects of HIFT exercise, on creatine kinase (CK) and lactate dehydrogenase (LDH) in blood serum in overweight adult men. Method : Twenty-two untrained non-smoker overweight men (age, 42.9 ± 5.6 years; body mass, 94.2 ± 9.3 kg; body height, 178.9 ± 4.5 cm; and BMI, 29.04 ± 3.3 kg/m2) volunteered to participate in this study and performed a session of HIFT exercise with 80-85% HRmax consisting of three sets of 10 exercises. Blood samples were collected before and immediately after training to measure serum CK and LDH levels. Results: The HIFT protocol significantly increased serum CK (Pre: 114.6 U/L; Post: 124.3U/L; p< 0.05{t=-5.48, p=0.001}); Also, LDH had a significant increase (pre:213.4 U/L, post: 225.4U/L; p<0.05{t=-4.09, p=0.001}). Conclusion: It can be concluded that HIFT with AMRAP (as many repeats as possible) protocol will lead to a significant increase in some indicators of muscle damage such as CK and LDH levels in overweight men. This protocol can lead to muscle damage in overweight 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 : Cold sprays (CS) are widely used in sport competitions as an effective, simple, and high available treatment. Aim: The aim of present study was to investigate immediate and longtime effects of CS application onto the knee joint anterior-medial area of dominant leg on timing and activation pattern of selected muscles during one-leg landing. Materials and Methods: Thirty (15 control and 15 experimental) able-bodied male participated in this study. Electromyography activity of vastus medialis, rectus femoris, vastus lateralis, biceps femoris, semiendineus and medial gastrocnemius were recorded during one-leg landing tests (with dominant leg) for each of three conditions including before CS application (pre-test), immediately after (post-test 1), and 20 min later (post-test 2). To determine the effect of group and time on each dependent variable, three independent 2×2 multivariate repeated measures analyses of variance were performed (α < 0.05). Results : The results showed following trends rather than significant differences: the muscles in the experimental group had lower activity level and later onset immediately after CS application compared to before application, and they had higher activity level and sooner onset after 20 min from removing CScompared to immediate application. No significant interaction was found for normalized peak activation and time to peak activation ( P > 0.05). However, decrease in skin temperature after cold spray application was observed. Conclusion : These results show short-time cold application, which is so practical after many injuries for returning athletes to sport environment, may not predispose individuals to risk of re-injury or failed landing mechanism.