Introduction: Blood flow restriction training combined with ergogenic supplements such as citrulline malate can affect muscle hypertrophy and IGF-1 levels by enhancing anabolic pathways. The general aim of this study was to determine the effect of twelve weeks of blood flow restriction exercises with citrulline malate supplementation on hypertrophy and IGF-1 in young male athletes.

Methods: In this experimental study, 40 young male athletes with normal body mass index from Tabriz were randomly assigned to four groups: BFR training + supplement, BFR training + placebo, supplement, and control + placebo. The two training groups exercised for 12 weeks, and cuff pressure increased from 130 to 200 mmHg. Citrulline malate supplementation was administered at a dose of 8 g/kg body weight, 30 to 60 minutes before exercise. This study was conducted in a double-blind manner. Serum IGF-1 levels were assessed by ELISA and hypertrophy of quadriceps and biceps muscles was assessed by limb circumference. After confirming the normality of the data with the Shapiro-Wilk test, analysis of covariance, Tukey's post hoc test, and paired t-test were used and analyzed with SPSS software version 22 and a significance level of 0.05.

Results: Twelve weeks of blood flow restriction training with citrulline malate supplementation had a significant effect on biceps and quadriceps hypertrophy (p=0.001), serum IGF-1 (p=0.001) in young male athletes.

Conclusion: BFR training is an effective tool for improving training results and increasing muscle growth factors such as IGF-1. Research findings recommend its inclusion in exercise programs to optimize muscle hypertrophy.