AbstractAging is associated with increased oxidative stress, chronic inflammation, and decreased telomere length (TL). However, the lifestyle of master athletes can lead to a reduced risk of these conditions, and thus attenuates aging and performance deterioration. We aimed to analyze the relationships between TL and relative performance (RP), and their relation to adiposity, oxidative stress, and inflammation in endurance (END) and sprint/power (SPW) master athletes (MAs). Twenty-two world-class MAs visited the laboratory for anamnesis, anthropometrics, and blood sampling. Inflammatory and oxidative stress parameters were assessed using commercial kits. Relative TL was determined in leukocytes through qPCR analyses. A positive association was observed between RP and TL in both groups (SPW: r=0.641; END: r=0.685) and the whole sample (r=0.594). The IL6/IL10 ratio presented an inverse correlation with RP in the whole sample (r=–0.580). Body mass index also demonstrated a negative correlation with TL for the END group (r=–0.690) and the whole sample analysis (r=–0.455). Moreover, the IL6/IL10 ratio was negatively associated with strength/power training hours (r=–0.464), whereas the CAT/TBARS ratio was negatively associated with aerobic training hours (r=–0.482). In conclusion, TL of MAs was associated with RP regardless of the training model (endurance or sprint/power), and inflammation and adiposity were associated with shorter telomeres.