Fig. 1

Running speed, calculated on the basis of each athlete’s best performance record in a 5,000 m race, was higher in individuals with the D/D or I/D genotype than in those with the I/I genotype (unpaired t test p = 0.023). The running speed of D/D individuals tended to be higher than that of I/I individuals (Tukey–Kramer p = 0.053). A linear trend was observed between genotype and 5,000 m running speed (Spearman rank correlation coefficients r = 0.345; p = 0.042). Data are shown as the mean and standard deviation (SD)