Author(s): KAMIYA-SAITO, M., HOMMA, H., KOZUMA, A., KOBATAKE, N., OKAMOTO, T., NAKAZATO, K., KIKUCHI, N., Institution: NIPPON SPORT SCIENCE UNIVERSITY, Country: JAPAN, Abstract-ID: 1803

INTRODUCTION:
MCT2 and MCT4 mediate complementary lactate uptake and efflux during high-intensity exercise. The MCT2 rs3763980 TA and MCT4 rs11323780 TT genotype combination has been associated with lower maximal post-exercise blood lactate concentration (Maculewicz et al. 2025). Lactate acts as a signalling molecule promoting muscle fibre-type remodelling toward more oxidative phenotypes (Zhou et al. 2024). Consequently, individual differences in lactate metabolism attributable to genetic traits may affect weightlifting performance, which requires a high explosive force relative to the body mass. This study examined the association between MCT2 rs3763980 and MCT4 rs11323780 polymorphisms with weightlifting performance in elite athletes.
METHODS:
A total of 215 elite weightlifters (121 men, 94 women) and 306 controls (143 men, 163 women) were recruited. Genomic DNA was extracted from saliva using an Oragene DNA kit. Genotyping of MCT2 rs3763980 (MCT2) and MCT4 rs1055013 (MCT4) polymorphisms was performed using TaqMan probe assays (WL) and the Japonica Array® v2 (CON). Rs1055013 is in complete linkage disequilibrium with rs11323780 (r² = 1.0). Weightlifting performance was assessed by converting the combined total of self-reported best records in the clean, jerk, and snatch movements into Wilks’ points adjusted for body mass and sex. Hardy–Weinberg equilibrium (HWE) and genotype frequencies were compared using the chi-square test. In the WL group, performance was compared between the MCT2 TA + MCT4 T allele group and the other genotypes using a one-way ANOVA.
RESULTS:
All examined polymorphisms were in HWE in the CON. No significant differences in genotype frequencies were observed between groups for either MCT2 (p = 0.60) or MCT4 (p = 0.30) genotype. The frequency of the MCT2 TA + MCT4 T allele (TA+TT) combination was 39.5% in the WL and 42.8% in the CON, with no significant difference between groups (p = 0.46). Among WL, those with the TA+T allele combination showed significantly higher combined performance than those with other genotypes (196.9 ± 29.8 vs. 188.4 ± 24.1, p = 0.027).
CONCLUSION:
The MCT2 rs3763980 TA genotype and MCT4 rs1055013 T allele combination was associated with superior weightlifting performance among elite athletes, although genotype frequencies did not differ between WL controls. Future studies should examine the effects of MCT2 and MCT4 polymorphisms on skeletal muscle characteristics, such as muscle fibre composition, to clarify the mechanisms underlying the association between these genetic variants and performance.

Maculewicz et al. 2025. 'The interactions between monocarboxylate transporter genes MCT1, MCT2, and MCT4 and the kinetics of blood lactate production and removal after high-intensity efforts in elite males: a cross-sectional study', BMC Genomics, 26: 133.
Zhou et al. 2024. 'Lactate-induced metabolic remodeling and myofiber type transitions via activation of the Ca(2+)-NFATC1 signaling pathway', J Cell Physiol, 239: e31290.