Abstract
BACKGROUND: Peak oxygen consumption during exercise (VO2peak), is a direct measure of cardiorespiratory fitness (CF), a key indicator of physical function and overall health. However, the molecular changes that underpin VO2peak variation are not clear. Our objective is to understand the microRNA (miRNA) signatures that relate to VO2peak variation, which could provide insights to novel mechanisms that contribute to low VO2peak. METHODS: We used small RNA sequencing to analyze baseline, cross-sectional serum samples from 72 participants (70- to 91-year old). We analyzed samples from individuals with low or high VO2peak (N = 18/group) as well as samples from 36 randomly selected participants spanning the entire spectrum of VO2peak. We used LIMMA analysis package for regression analysis and to identify differentially expressed miRNAs. RESULTS: We identified 1055 miRNAs expressed in all serum samples. Expression of 65 miRNAs differed between participants with low and high VO2peak (P < .05). After P-value adjustment, expression of 5 miRNAs (miR-1301-3p, -431-5p, -501-5p, -519a-3p, and -18a-3p) remained significantly different (FDR = 0.05). The Area Under the Curve for the five miRNAs ranged from 0.77 to 0.84. The optimal sensitivity and specificity ranged from 70% to 80% and 80% to 90%, respectively. After adjustment for age and sex covariates, 46 miRNAs significantly correlated with VO2peak (P < .05) and miR-519a-3p remained significant based on adjusted P-values. CONCLUSIONS: We identified a miRNA signature of VO2peak in older individuals that might provide insights to novel mechanisms that drive low VO2peak. Future studies will validate the findings in a larger, longitudinal study cohort.