OBJECTIVES This study set out to develop and administer an 8-week G-tolerance reinforcement exercise program and examine changes to the body composition, cardiovascular endurance, isokinetic muscular function, and G-tolerance ability of air force cadets according to the ACTN-3 gene polymorphism, thus testing the effects of the program on air force cadets according to the ACTN-3 gene polymorphism. METHODS For those purposes, the investigator analyzed the gene polymorphisms of ACTN-3 of 30 air force cadets, administered the developed G-tolerance reinforcement exercise program to and conducted analy-sis of its effects on their body composition, cardiovascular endurance, isokinetic muscular functions(mus-cular strength and endurance), and G-tolerance capacity(6G/30sec). RESULTS Found a significant increase in skeletal muscle mass in the RR and RX types, and body fat per-centage in the XX type. the program caused a significant increase to the of the subjects across all the geno types and to their cardiovascular endurance in the RX and XX types. the dominant knee joint(right leg) and found a significant increase in the peak torque per body weight in the RX and XX type. As for the dominant knee joint(right leg), there was a significant increase in the total work per body weight in the RR, RX, and XX types. the G-tolerance ability in the RX than in the RR type, and and G-tolerance ability of XX type was also increased. CONCLUSIONS In summary, those findings demonstrate that there were differences in the changing pat-terns of air force cadets G-tolerance ability according to the ACTN-3 gene polymorphism(RR, RX, and XX) after the G-tolerance reinforcement exercise program and that there was a more increase in the G-toler-ance ability in the RX than in the RR type, and G-tolerance ability of XX type was also increased. Therefore, the G-tolerance reinforcement exercise program is verified as effective for reinforcing the G-toleran capac-ity of air force cadets who have either genotype RX or XX.