Abstract: Monocarboxylate transporter 1 (MCT1; SLC16A1) is a proton-dependent cotransporter/exchanger, located on the apical membrane of cells. MCT1 is able to transport several monocarboxylates including lactate, pyruvate and acetate, which makes this protein critical in terms of the athletic performances. The rs1049434 polymorphism in the MCT1gene was frequently associated with the performance of the athletes in different populations. The present study aims to decipher any possible association of the rs1049434 polymorphism with the personal best of elite track and field athletes. A total of sixty elite athletes (31 sprint/power and 29 endurance) and twenty control/sedentary with the ages of 18-35 voluntarily participated in the study. The International Association of Athletics Federations (IAAF) score scale was used to determine the performance levels of the personal best (PB) of the athletes. Whole exome sequencing (WES) was performed by the genomic DNA isolated from blood of the participants. Sport type, sex and PB were chosen as the parameters to compare within and between the groups by logistic regression models. The sex was not the criterion that was significantly different between or within the groups. Although PB scores were not significant within the sprint/power group, it was significant within the endurance group by the codominant (p=0.044), dominant (p=0.016) and over-dominant (p=0.048) models. The rs1049434 polymorphism in the MCT1 gene may be linked to the PB of the endurance athletes. However, other genetic alterations should be regarded to conclude the effect of this polymorphism. The multi-factorial genetic background that could associate with the athletic performance

is still under investigation in our research group. Nevertheless, further studies with more participants are needed.