درخت حوزه‌های تخصصی

Purpose: For most trainers, the relationship between training volume and intensity as key components is a very important and effective issue. Therefore, the aim of the present study was to investigate the relationship between two key components of exhausting running at Heart Rate Deflection Point (HRDP) in girls. Methods: A number of 40 girls of physical education of Mohaghegh Ardabili University were selected as subjects with an age range of 19 to 23 years. Then, they ran individually in four separate sessions with an intensity of 70, 80, 90 and 100% of heart rate breaking point with a minimum interval of 72 hours. Using non-linear regression, the relationship between exercise volume and intensity was analyzed. Results: The findings showed that the inverse relationship between the volume (as a dependent variable) and the intensity (as an independent variable) of exhausting running at the HRDP of young girls' follows the non-linear 2nd degree function. Conclusion: According to the results of this study, it can be said that the inverse relationship between the volume and the intensity of running is non-linear. The noteworthy point is that in this estimation, the training volume was fitted based on the intensity, the relevant equation, which has a practical aspect for sports science trainers and researchers. Heart rate, as an important physiological index available to all coaches, can easily estimate the running time of young girls using the fitted equation.

Background and purpose: Caffeine is a widely used and available physiological stimulant that is effective in sports performance. The purpose of this study was to investigate the effect of caffeine consumption and exercise on fatigue and cardiovascular responses in active men.Materials and methods: The statistical population of this research was made up of all male students of physical education in the age range of 19 to 27 years with at least three activity sessions per week. 15 of them were selected as subjects and they performed the exercise protocol in two stages (the first stage by eating placebo and the second stage by eating coffee). Subjects consumed 5 mg/kg of coffee in the first session under placebo conditions, and in the second session, subjects consumed 5 mg/kg of coffee one hour before the test. Blood samples were collected before taking placebo or caffeine and after the test. Findings: The results of the correlated t-test showed that the consumption of caffeine supplements significantly increased the time to reach fatigue and the index of oxygen consumption after exercise. In general, it can be said that active men can use 6 mg/kg of caffeine supplement one hour before sports activity to improve the time to reach fatigue.

Purpose: The aim of this study was to investigate the effect of high-intensity interval training on serum levels of irisin, follistatin, and metabolic status of overweight and obese women. Methods: The current research was a semi-experimental type with a pre and post-test design. 30 women with an average age of 22.9±2.11 years, weight 82.45±6.1 kg, BMI above 28 kg/m2) voluntarily participated and they were randomly divided into two groups of 15 people including HIIT (4 bouts of 60 seconds of running at an intensity of 80-90% HRmax with a 4-minute rest in the first four weeks) and control (did not have a regular exercise program). Blood samples were taken 24 hours before the start of the training period and 48 hours after the end of the last session, to measure irisin, Follistatin, and metabolic status, by ELISA method. Then, an independent t-test was used to examine changes between groups, and a correlated t-test was used for intragroup comparison. Data analysis was done by SPSS version 25 software at a significance level of 0.05. Results: After 8 weeks of intervention, the HIIT group showed that HIIT exercises led to a significant increase in irisin(p=0.25) and follistatin(p=0.12), triglyceride (p=0.30), and total cholesterol levels. (p=0.41), LDL (p=0.14), VLDL (p=0.17), weight (p=0.31), fat percentage (p =0.21)) and BMI (p=0.251); And there was a significant increase in maximum oxygen consumption (p=0.11). However, no significant change was observed in the amount of HDL (p=0.55). Conclusion: According to the findings of the present study, in order to maintain or prevent the decrease in bone density of postmenopausal women, resistance exercises can be recommended.