Lack of association between PBMC telomere length and endurance exercise

Telomeres are repetitive DNA located at the ends of chromosomes that preserve genomic stability. Excessive leukocyte telomere shortening is associated with cardio-metabolic disease and increased mortality risk. Although most studies indicate exercise training could attenuate leukocyte telomere attrition, data is somewhat equivocal. The inconsistencies could be partly explained by the different populations of leukocytes isolated for telomere length assessment. Accordingly, average peripheral blood mononuclear cell (PBMC) and whole blood leukocyte telomere length were assessed in 44 endurance athletes and 40 healthy controls using quantitative PCR. While whole blood leukocyte telomeres were, on average, 6.1% longer in endurance athletes compared to controls, PBMC telomere length was similar between the two cohorts in age and sex-adjusted analyses (athletes vs controls, mean T/S ratio ± SE: 3.25 ± 0.05 vs 3.23 ± 0.05, p = 0.72). Other than a weak inverse correlation with sitting (r = -0.25, p = 0.03), no statistically significant correlations were found between PBMC telomere length and exercise parameters. Unlike whole blood leukocytes, PBMC telomere length is not associated with endurance exercise and exercise parameters. These findings suggest the need for future work to quantify short and long telomeres of sorted immune cell populations and to measure them in context with cell counts and exercise traits.