Today, various dietary supplements are taken to improve endurance performance during physical activity. These supplements have proven to be very successful in controlling and balancing various hormone levels and have contributed to the prevention and healing of metabolic disorders and physical injuries. In this study, we sought to investigate the effects of the ACTN3 gene and nutrient supplementation, including beta-alanine, ashwagandha, L-carnitine, and iron, on athletic performance. The ACTN3 gene has been identified as a potential genetic determinant of athletic performance, particularly in activities that require high levels of power and strength. This study investigated the interaction between the ACTN3 gene and supplementation and highlighted the potential for personalized approaches to improve athletic performance. 24 subjects per group, were randomized in a parallel-group design to examine the effects of supplementation on the ACTN3 gene and athletic performance over a 21-day intervention period. Participants in the intervention were divided into four groups of six members each. The same subjects who did not take supplements formed the control group. In addition, the subjects were divided into 4 groups (G1, G2, G3, and G4), each consisting of subgroups of control and a treated. All treated groups (TG1, TG2, TG3, and TG4) received 4 supplements for 21 days, namely S1 (ashwagandha), S2 (iron), S3 (beta-alanine) and S4 (L-carnitine), together with the 4 control groups, i.e. CG1, CG2, CG3 and CG4, who received no supplements during the same period. In particular, this study determines the effect of these 4 supplements on actn3 gene expression, testosterone, cholesterol and BUN levels of the participants. The P-values determined for all parameters showed statistically significant values and the final result showed that all supplements had positive effects on the tested parameters. The result showed a highly significant difference between the intake of supplements before and after the intake of 24 athletes per group on the ACTN3 gene expression level and biochemical indicators.