Influence of Middle-Distance Running on Muscular Micro RNAs

A specific subset of micro RNAs (miRs), including miR-133 and miR-206, is specifically expressed in muscle tissue, so that they are currently defined as muscular miRs (myomiRs). To further elucidate the role of myomiRs in muscle biology, we measured miR-133a and miR-206 in plasma of 28 middle-age recreational athletes. The study population consisted of 28 middle aged, recreation athletes (11 women and 17 men; mean age, 46years) who completed a 21.1km, half-marathon. The plasma concentration of miR-133a and miR-206, the serum concentration of creatine kinase (CK) and high-sensitivity (HS) cardiac troponin T (cTnT), as well as capillary lactate, were measured before and immediately after the run. The median serum concentration of total CK (257 versus 175U/L; p<.001), cTnT (17.8 versus 5.6ng/L; p<.001), and the plasma values of both miR-133a (4.22 versus 0.64x10(-4); p<.001) and miR-206 (1.36 versus 0.63x10(-4); p=.001) were considerably increased immediately after the half-marathon run. In multivariate analysis only post-exercise capillary lactate was found to be independently associated with running time. A significant and independent correlation was observed between plasma variations of the two miRs, but not with other physiological or laboratory parameters. The results of this study suggest that the biological significance of miR-133a and 206 variation after middle-distance running parallels but not overlaps the release of biomarkers of nonspecific tissue damage. Enhanced plasma values of these myomiRs may hence reflect a physiological response to high-intensity and/or prolonged exercise rather than tissue injury.