Effect of Resistance and HIIT training, with and without blood flow restriction (BFR), on GH and IGF-1 levels in men

Background: Blood flow restriction (BFR) is a method that involves using inflatable cuffs to carefully limit blood flow into the arteries and adjust the outflow from the veins in working muscles by applying controlled pressure. Objective: This study aimed to compare the levels of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in young men after eight weeks of resistance training (RT) and high-intensity interval training (HIIT), with and without blood flow restriction (BFR). Materials and methods: This study employed a quasi-experimental design, with a sample of 40 men aged 18–25, who were randomly assigned to one of four groups: RT, HIIT, RT+BFR, or BFR+HIIT, with 10 participants per group. Hormonal responses (GH and IGF-1) were assessed at baseline (week 1) and after 8 weeks of training, both pre- and post-training. Data were analyzed using a 2-way [4 (group) × 2 (time)] ANOVA in SPSS (version 26), with statistical significance set at P < 0.05 Results: After eight weeks of training, a comparison of the mean pre-test and post-test scores revealed that RT led to significant increases in both GH and IGF-1 levels at weeks 1 and 8. The RT+BFR group showed significant increases in GH at both time points and in IGF-1 at week 8. In the HIIT groups, both GH and IGF-1 increased significantly immediately after the interventions (p < 0.05). However, no significant differences were observed between the groups, indicating no interaction effect. Conclusion: RT+BFR was effective in stimulating hormone responses; however, RT demonstrated more consistent hormone responses than the other training groups. Furthermore, the combined intervention (BFR+HIIT) did not induce greater metabolic stress, as assessed by GH and IGF-1, compared to sole HIIT.