title: Plasma microRNA levels differ between endurance and strength athletes.
abstract: OBJECTIVE
  MicroRNAs (miRNAs) are stable in the circulation and are likely to function in inter-organ communication during a variety of metabolic responses that involve changes in gene expression, including exercise training. However, it is unknown whether differences in circulating-miRNA (c-miRNA) levels are characteristic of training modality.
  
  
  METHODS
  We investigated whether levels of candidate c-miRNAs differ between elite male athletes of two different training modalities (n = 10 per group)--endurance (END) and strength (STR)--and between these groups and untrained controls (CON; n = 10). Fasted, non-exercised, morning plasma samples were analysed for 14 c-miRNAs (miR-1, miR-16-2, miR-20a-1, miR-21, miR-93, miR-103a, miR-133a, miR-146a, miR-192, miR-206, miR-221, miR-222, miR-451, miR-499). Moreover, we investigated whether c-miRNA levels were associated with quantitative performance-related phenotypes within and between groups.
  
  
  RESULTS
  miR-222 was present at different levels in the three participant groups (p = 0.028) with the highest levels being observed in END and the lowest in STR. A number of other c-miRNAs were present at higher levels in END than in STR (relative to STR, ± 1 SEM; miR-222: 1.94 fold (1.73-2.18), p = 0.011; miR-21: 1.56 fold (1.39-1.74), p = 0.013; miR-146a: 1.50 fold (1.38-1.64), p = 0.019; miR-221: 1.51 fold (1.34-1.70), p = 0.026). Regression analyses revealed several associations between candidate c-miRNA levels and strength-related performance measures before and after adjustment for muscle or fat mass, but not following adjustment for group.
  
  
  CONCLUSIONS
  Certain c-miRNAs (miR-222, miR-21, miR-146a and miR-221) differ between endurance- and resistance-trained athletes and thus have potential as useful biomarkers of exercise training and / or play a role in exercise mode-specific training adaptations. However, levels of these c-miRNAs are probably unrelated to muscle bulk or fat reserves.
authors.affiliation: Health and Exercise Sciences Research Group, University of Stirling, Stirling, Scotland.
authors.forename: Sophie L
authors.initials: SL
authors.lastname: Wardle
authors.affiliation: School of Life Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland.
authors.forename: Mark E S
authors.initials: ME
authors.lastname: Bailey
authors.affiliation: Lithuanian Sports University, Kaunas, Lithuania.
authors.forename: Audrius
authors.initials: A
authors.lastname: Kilikevicius
authors.affiliation: School of Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland.
authors.forename: Dalia
authors.initials: D
authors.lastname: Malkova
authors.affiliation: School of Life Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland.
authors.forename: Richard H
authors.initials: RH
authors.lastname: Wilson
authors.affiliation: Lithuanian Sports University, Kaunas, Lithuania.
authors.forename: Tomas
authors.initials: T
authors.lastname: Venckunas
authors.affiliation: Health and Exercise Sciences Research Group, University of Stirling, Stirling, Scotland.
authors.forename: Colin N
authors.initials: CN
authors.lastname: Moran
mesh_terms: D000328:Adult; D006801:Humans; D035683:MicroRNAs / Q000097:blood*; D013177:Sports; D055815:Young Adult
chemical_list: D035683:MicroRNAs