حسن فرجی

Background: Caffeine is widely recognized as a potent ergogenic aid commonly used to enhance exercise performance and recovery. However, individual responses to caffeine can vary significantly, a variability that might be explained by genetic differences.Aim: This study aimed to investigate the influence of the CYP1A2 rs762551 SNP on the effects of caffeine (CAF) consumption on growth hormone (GH) and testosterone (TS) levels response to resistance exercise (RE) in male athletes.Materials and Methods: Thirty resistance-trained men (mean age 21.72±4.06 years, weight 77.31±14.07 kg, height 179.31±5.08 cm) participated in a randomized, double-blind, placebo-controlled, crossover study. They consumed either CAF (6 mg/kg) or placebo (PL; 6 mg/kg maltodextrin) one hour before performing a RE protocol including three sets with 85% of 1RM and two-minute rest. CYP1A2 genotyping categorized participants as AA homozygous ("fast" metabolizers) or AC heterozygous ("slow" metabolizers). GH and TS levels were measured by ELISA methods.Results: Repeated measures ANOVA showed significant differences in GH levels across time (F=10.94, P=0.000), with significant time-group (F=4.3, P=0.019) and time-genotype-group interactions (F=3.83, P=0.024). One-way ANOVA indicated significant differences in GH levels between CAF and PL conditions in AA individuals, but not in AC/CC genotypes. For testosterone, significant effects of time (F=14.88, P=0.000) and time-group interaction (F=3.197, P=0.045) were observed. Post-RE CAF supplementation significantly increased serum GH and TS levels in AA individuals compared to PL. Both CAF and PL groups showed increased serum hormone concentrations post-exercise.Conclusion: In conclusion, the study demonstrated that caffeine consumption significantly increased serum levels of growth hormone and testosterone in individuals with the AA genotype of the CYP1A2 rs762551 SNP. These findings suggest that genetic variations play a role in the hormonal response to caffeine, which may have implications for exercise performance and recovery strategies.