Association of Polymorphism with Body Somatotype and Cardiorespiratory Fitness in Young Healthy Adults.

encodes the protein α-actinin-3, which affects the muscle phenotype. In the present study, we examined the association of R577X polymorphism with body somatotype and cardiorespiratory fitness in young, healthy adults. The study group included 304 young adults, in whom cardiorespiratory fitness was evaluated and the maximum oxygen uptake was determined directly. The somatotype components were calculated according to the Heath-Carter method. Genotyping for the gene was performed using a polymerase chain reaction followed by high-resolution melting analysis. In the female group, a lower maximal heart rate (HRmax) was more strongly associated with the RR genotype ( = 0.0216) than with the RX and XX genotypes. In the male group, the RX genotype, as compared with other genotypes, tended to be associated with a lower percentage of adipose tissue ( = 0.0683), as also reflected by the body mass index ( = 0.0816). gene polymorphism may affect cardiorespiratory fitness. Our analysis of gene polymorphism does not clearly illustrate the relationships among genotype, body composition, and somatotype in young, healthy adults.