Journal of School of Public Health and

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  Background and Aim: Considering the uncertainties about associations between orexin-A and obesity, the present study was conducted to determine the effects of 8 weeks of endurance training and high intensity interval training ( HIIT) on plasma levels of orexin-A and some anthropometric parameters in obese adolescent boys.

  Materials and methods: In this semi-experimental project 35 healthy, inactive and obese boys (mean age 15.5±0.69 years, mean body mass index (BMI) = 28.72±2.20, equal to or higher than the 95^th percentile) were randomly divided into three groups of equal numbers, namely, control, endurance training, and HIIT. The endurance training and the HIIT group participated in eight weeks of endurance training (25-40 minutes running per day, with an intensity 65-85% Heart Rate Reserve) and eight weeks of HIIT (30 seconds running with an intensity 90-95% Heart Rate reserve, 4-7 repetitions a day and two minutes of a rest interval with 50-55% Heart Rate reserve), three days per week, respectively. Plasma levels of orexin A, anthropometric measurements (waist-to-hip ratio, body fat percentage and body mass index) and VO2 max were determined before and 48 hours after the last session of the training. Data were analyzed and are reported as mean ± SD using repeated measure ANOVA (p < 0.05).

  Results : Despite a decreasing trend in the plasma orexin-A level in the control and HIIT groups and its rising trend in the endurance training group, no statistically significant differences were observed between the control and experimental groups (P>0.05). However, HIIT and endurance training caused significant reductions in the anthropometric parameters such as body fat percentage (8.7%, 9.7%), body mass index (1.6%, 1.9%) and waist to hip ratio (2.7%, 2.9%), accompanied by a significant increase in the VO2 max (6.7%, 10.9%) (p<0.05).

  Conclusion: Endurance training is more effective than HIIT as regards improvement in body composition of obese adolescent boys, although the changes may not be in line with changes occurring in plasma orexin-A levels. It is recommended that more studies be conducted in this area, controlling sleep, nutrition and changes due to puberty, and with longer durations of exercise.

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Background and Aim: Orexin is a hormone involved inoverweight and obesity and a regulator of glucose metabolism. The purpose of this study was to determine the effects of a high-intensity interval training (HIIT) on plasma levels of orexin-A (OXA) and insulin resistance in overweight women.
Materials and Methods: In a semi-experimental study, 24 overweight women (aged 20-25 years; body mass index (BMI), 25-30 kg/m²) were divided into 2 groups, namely, a control (n=12) and a training (n=12) group. The training group performed selective HIIT including 6 movements for 6 weeks (3 sessions/week). Initial and final blood markers were measured in blood samples collected 24 hours after the test. The data were analyzed using the paired and independent sample t-tests; a p<0.05 was considered to show statistical significance.
Results: There were no statistically significant differences between body weight, BMI, plasma levels of glucose, insulin and insulin resistance before and after the period in either the training or control group (p>0.05). Neither were there any significant differences between the training and control groups after the 6-week period as regards plasma levels of glucose, insulin, OXA or insulin resistance (p>0.05).
Conclusion: The findings of this study show that a 6-week high-intensity interval training has no influence on plasma OXA or insulin resistance in overweight women.