Abstract
The discovery of microRNAs (miRNAs) and following studies reporting that miRNAs are stably present in the circulation, paved the way for possible use of miRNAs as biomarkers. Identification of circulating miRNAs that are functional upon delivery to the recipient cells, suggests miRNAs play roles in cell-to-cell communication as well as hormones and cytokines. This review provides a basic understanding of miRNAs and the current understanding of circulating miRNA as biomarkers and focuses on their putative roles and regulation under stressed conditions including physical exercise.
