Recently, microRNA molecules (miRNAs) have been identified as essential intracellular mediators of processes inherent in exercise adaptation including angiogenesis (Zhang, 2010), inflammation (Davidson-Moncada et al. 2010), mitochondrial metabolism (Chan et al. 2009; Dang, 2010), cardiac/skeletal muscle contractile force generation, and tissue hypertrophy (Davidsen et al. 2011).
These short single stranded miRNAs are incorporated into the RNA-induced silencing complex (RISC) which regulates protein expression (Wessner et al., 2011).
The discovery of microRNAs (miRNAs) provides a new avenue that will extend our knowledge of factors controlling skeletal muscle function during tapering periods. miRNAs may also improve our understanding and application of current tapering approaches as well as enable the identification of new identified strategies and targets aimed at maintaining and/or improving skeletal muscle health before competitions
In response to increased use through regular exercise training, skeletal muscle can increase its size and capacity to produce force (Fry, 2004), improve its resistance to fatigue and enhance its oxidation of carbohydrates and fats (Coyle, 2000).
A suite of miRNAs, highly enriched in cardiac and/or skeletal muscle (referred to as myomiRs), has recently been identified and include miR-1, miR-133, miR-133a, miR-133b, miR-206, miR-208, miR-208b, miR-486 and miR-499 (McCarthy & Esser, 2007; Callis et al. 2008 and van Rooij et al. 2009). miR-1 stimulates differentiation through its direct inhibition of HDAC4, an inhibitor of differentiation, while miR-206 indirectly inhibits helix–loop–helix, the latter, a repressor of Myo-development.
Up to now it is unproven whether miRNAs are involved in tissues repair processes within skeletal muscle tissues after acute bouts of training sessions but a small number of striated muscle-specific miRNAs so called MyomiRs have been identified and shown to have an important role in myogenesis, muscle growth and cardiac function and hypertrophy (Zhang et al., 2010). miR-206, a muscle-specific miRNA that is up-regulated by exercise in the intracellular space (Nielsen et al.2010) may be involved in tissue repair and adaptation.
Data defining circulating micro-RNA (c-miRNA) behavior in the settings of acute exercise bouts and sustained exercise training in healthy humans are lacking. Identification of miRNAs specifically regulated by exercise could reveal unique biomarkers of exercise physiology and would lend significant insight into the molecular control of exercise adaptation.
The purpose of this study was to assess miR-1 and miRNA-206 concentrations in handball athletes at rest and after a proposed handball game after 8 weeks period of training program followed by five days of tapering. Results will be correlated to some handball performance skills before and after tapering.