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Background and Aim: Exercise aerobic is associated with increased creatine kinase and blood lactate immediately after exercise, leading to increased muscle damage and undesirable changes in many cellular markers including serum creatine kinase. In such situations, consuming nutrients and supplements such as coenzyme Q10 may prevent metabolic stress damage by increasing buffering power. However, comprehensive studies have not been performed on the effects of this nutrient on the index of muscle injury and fatigue caused by exercise.
Methods & Materials: For this purpose, 20 inactive volunteer men were randomly divided into two groups of 10-person Coenzyme Q10 supplement (2.5 mg/kg body weight) and quasi-drug (2.5 mg/kg body weight Dextrose). All subjects participated in the Bruce test exercise contract after 14 days of supplementation. Blood sampling was performed in four stages including baseline, after supplementation, immediately after exercise and two hours after exercise. Creatine kinase, lactate and cortisol indices of both groups were measured during these four stages. Data were analyzed by means of standard deviation and repeated measures ANOVA, Bonferroni post hoc and Independent T-test using SPSS V. 17 at the significant level of 0.05.
Ethical Considerations: This article has been approved by the ethics committee of Tabriz School of Medical Sciences with the ethics code IRCT 201203104663N8.
Results: The results showed that 14 days of Coenzyme Q10 supplementation had a significant effect on cortisol level (P<0.05). In addition, one session of exhausting aerobic activity increased creatinine kinase and lactate (P<0.05). On the other hand, creatinine kinase did not differ significantly after exercise (P>0.05). 
Conclusion: According to the results of the present study, 14-day supplementation of Coenzyme Q10 may reduce the cellular damage induced by exhaustive aerobic activity in inactive men and prevent an increase in blood lactate levels.

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Background and Aim: Obesity is a clinical condition that affects the growth-related hormonal system, especially in adolescents. High-Intensity Intermittent Training (HIIT) might reduce such destructive effects.
Methods & Materials: In this quasi-experimental research, among adolescent boys [age: 13-18 years, height: 154±8 cm, Body Mass Index (BMI): 27.05±1.4 kg/m²], 30 volunteer subjects were selected. The study participants were divided into 3 groups of short-term and long-term periodic exercises as well as controls. The short-term exercise group performed 9 bouts of 30 seconds with 150-second breaks between sessions; the long-term exercise group performed 4 bouts of 150 seconds with 240-second breaks between sessions 3 times a week for 8 weeks. Body composition and blood samples were obtained 48 hours before and after conducting the training protocol to measure the desired parameters. The changes of each index were analyzed by repeated-measures Analysis of Variance (ANOVA)  at the significant level of P<0.05.
Ethical Considerations: This study was approved by the Ethics Committee of Tabriz University (Code:  IR.TABRIZU.REC.1398.021).
Results: After 8 weeks of HIIT, growth hormone increased and thigh, arm circumference, and fat percentages decreased (P<0.05). However, no changes were detected in the insulin-like growth factor I, BMI, and weight of the examined subjects (P>0.05).
Conclusion: Short- and long-term HIIT have the potential to improve the growth hormone status and body composition of overweight adolescents.