درخت حوزه‌های تخصصی

Background: Sports and physical activity are important for the healthy growth and development of children. However, various contextual and interfering factors can hinder the development of sports and physical activity in children.   Aim : The purpose to identify the contextual and interfering factors affecting the development of sports and physical activity in children. Material and Methods: The present study adopts a combinatory approach, where the first stage is qualitative and exploratory, and the second stage is descriptive-survey. In the qualitative stage, 16 experts in the field of children's sports were interviewed using purposive sampling, and the collected data were analyzed using MAXQDA 2020 software. In the quantitative stage, SPSS software version 26 was used for exploratory factor analysis and t-tests, while PLS 3 software was used for confirmatory factor analysis. Results: The results of this study suggest that there are five contextual factors-personal and family, infrastructure and equipment, supportive, economic and managerial as well as five interfering factors-human resources, organizational, media activities, control and evaluation, and legislation. Furthermore, the results of confirmatory factor analysis indicated that the research measurement model was validated. Conclusions: In conclusion, it can be acknowledged that by considering the identified factors in the development of sports and physical activity in childhood, it is possible to address some of the challenges in the field of children's sports.

Background: Water polo (WP) is a sport with great aerobic/ anaerobic physiological demands. There are few studies that have evaluated the physical demands during the WP game and its relationship with the physiological indices of aerobic fitness Aim: Our aim was to determine the aerobic/ anaerobic profiles of the WP athletes through specific test. Materials and Methods: WP male athletes participated in this study (24.5±5.6 years, 85.9±10.3 kg, 183.0±6.3 cm, n=23). The athletes performed an anaerobic WP test (TAnaWP) to determine the height (Alt- cm) of the 1st/ 15th/ 30th jumps, total time(s) of the jumps (TT30) and the fatigue index (FI). Blood lactate kinetics were determined immediately after (Lac0 min) and during the recovery period; Lac 1/ 3/ 5/ 8/ 12 min. They also performed an aerobic water polo test (TAerWP) to determine maximal oxygen consumption (VO 2 max) a heart rate (HRmax), peak blood lactate (Lacp) and the second lactate threshold (LL2). Results: The following results (in cm) were obtained in TAnaWP: Alt1st (44±6), Alt15th (32±7) and Alt30th (24±9); TT30 (56.9±9.5); FI (42.0±12.5%); (Lac0), (Lac1), (Lac3), (Lac5), (Lac8) and (Lac12) (5.2±1.7; 7.8±1.6; 9.0±2.0; 9.4±2.2; 9.2±2.7; 8.5±2.2 mmol/L, respectively). The mean maximal values for the aerobic test were: VO 2 max=44.4±5.3 ml/kg/min, HRmax=174.3±9.1 bpm, Lacp=8.6±2.1 mmol/L. The values obtained at LL2 were: 157.5±13.5 bpm/ 90.5±8.2% HRmax). Conclusion: The proposed tests may be a possibility to determining the physiological fitness of WP athletes.

Background: Adropin is a newly identified bioactive protein that is important in energy hemostasis and vascular endothelial function. Aim : The purpose of the present study was to investigate plasma levels of adropin and nitrite/nitrate (NO), in elderly treated hypertensive subjects at baseline and follow-up after 6 weeks of high-intensity interval training (HIIT). Material and Methods: Forty-four elderly participants with treated hypertensives (age 61.09±5.82 years, 25 male and 19 female, BMI= 25.7±1.31 kg/m 2 ) were randomly assigned to either the high-intensity interval training (HIIT) or control group. The HIIT group received an intervention consisting of 10 intervals of 1.5 min at 85% to 90% of their heart rate reserve (HRR), separated by 2 min of rest at 50% to 55% of their HRR, in three sessions per week for a duration of six weeks. Plasma levels of adropin and NO were measured using enzyme-linked immunosorbent assay. The statistical analysis was performed by two-way repeated ANOVA to determine differences between groups and Pearson’s correlation coefficient to determine correlation. Results: The results showed that, following the six-week HIIT intervention, the plasma levels of adropin and NO significantly increased when compared to both control group ( P = 0.0016) and the baseline ( P = 0.0003) measurements. Peak oxygen consumption was increased after exercise training compared to the control group ( P =0.005). Δ adropin in the HIIT group showed a positive correlation with increased Δ NO (r= 0.707, P = 0.002) and Δ VO 2 peak (r= 0.836, P = 0.001), and a negative correlation with Δ DBP (r= 0.643, P = 0.025) and Δ SBP (r= 0.691, P = 0.013). Conclusions: The study findings suggests that HIIT can enhance both blood pressure and cardiorespiratory fitness. The observed increase in plasma level of adropin may have contributed to reduction of blood pressure by promoting nitric oxide production.