Effect of ACTN3 R577X genotypes on muscle strength and power in Brazilian mixed martial arts athletes

The purpose of this study was to compare the muscular performance of Brazilian MMA athletes in strength and power tests for different genotype groups of ACTN3 R577X polymorphism. Eighteen male professional Brazilian MMA athletes (RR=6, RX=9, XX=3) participated in this study. Subjects performed handgrip test, supine and squat exercises in 1RM and 70% of 1RM tests, and countermovement jump test. The subjects’ blood samples were drawn from an antecubital arm vein. Genomic DNA was extracted from leukocytes using the salting-out technique. ACTN3 R577X polymorphism was determined by PCR test. Although the findings indicate there was no association between the ACTN3 and upper body muscle performance (handgrip test, 1RM supine test, and 70% of 1RM supine test) (P>0.05), the MMA athletes with ACTN3 RX genotype presented better local muscle endurance than the RR athletes (P=0.02). Also, the dominant model (RR vs. RX+XX) of ACTN3 genotype presented better local muscle endurance (P=0.04). Regarding the explosive muscle power of the MMA athletes’ lower limbs, the recessive model (RR+RX vs. XX) of ACTN3 genotype showed greater responses (P=0.03).