Effect of 6-Weeks Resistance Training with High and Low Intensity on Muscle Growth and Damage Factors in Active Girls

Introduction: The intensity of exercise is an important factor in choosing the right exercise program. The aim of current study was effect of 6-weeks of resistance training with high and low intensity on muscle growth and damage factors in active girls. Methods: 45 active girls with mean age of 20.7 ± 1.3 years, weight 58.5 ± 2.4 kg, and BMI 23.1 ± 0.5 kg / m2 were randomly divided to High(15 students) and low(15 students) intensity resistance training and control (15students). The experimental groups performed their special training for 6 weeks. 48 hours before and after the main protocols blood samples were taken. Within-group variations with t-test and between-group variations were analyzed by two-way ANOVA with repeated measures (time * group). Results: There was a significant difference in the follistatin (P = 0.002), follistatin / myostatin ratio (P = 0.001), C-reactive protein (P = 0.006), growth hormone (P = 0.021) Testosterone (P = 0.007) and testosterone / cortisol ratio (P = 0.033) were observed between the groups. The post-hoc test showed a significant difference in follistatin, follistatin/myostatin ratio, testosterone, testosterone/cortisol ratio, growth hormone and c-reactive protein in both experimental and control groups (P <0.05). However, among all the factors, only a significant increase in growth hormone was observed in the high intensity training group compared to low intensity resistance training group (P = 0.04). Conclusions: Although there were significant difference in growth hormone between high and low intensity groups. However, intense resistance training seems to be as effective in terms of hormonal and metabolic changes as low-intensity resistance training.